tag:blogger.com,1999:blog-15899592538626747122024-03-17T15:11:07.149+01:00Aeronetworks sro - Airborne LinuxAutonomous planes, trains and cranes...Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.comBlogger215125tag:blogger.com,1999:blog-1589959253862674712.post-52603483291212626362024-02-20T12:29:00.020+01:002024-03-17T15:10:34.780+01:00Wide Band Aerials For 1700 to 2400 MHz, M1 - M6 Band<p style="text-align: left;">The 1700 to 2400 MHz band (M1 to M6) is a good band for the secondary control channel of air and ground robotic vehicles. Little radios made by <i>Doodle Labs</i> in Singapore are popular and this is an antenna solution specifically aimed at the <i>Meshrider</i> radios (<a href="https://doodlelabs.com/products/mesh-rider-radios/nano/">https://doodlelabs.com/products/mesh-rider-radios/nano/</a>).<br /></p><p style="text-align: left;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJcJJhEysC-NI3k9-OIJVRMtAtIiKazBODBSioRcNVGjqkwIrrNs6lRIWc6ijunvY5OqCdMaZ54ilTjaRCuzi3jjXwJ4nuSuT9Xb_ms8NqaANWBhvzHftG7ew5s4MPwM3fyEhiVBm-Walw5g14MXaMZrEGldUJMG2CfNC85AEjouT2kiYTR_MMzPWK2hE/s2663/lpa-1700-2400.jpg" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1486" data-original-width="2663" height="179" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJcJJhEysC-NI3k9-OIJVRMtAtIiKazBODBSioRcNVGjqkwIrrNs6lRIWc6ijunvY5OqCdMaZ54ilTjaRCuzi3jjXwJ4nuSuT9Xb_ms8NqaANWBhvzHftG7ew5s4MPwM3fyEhiVBm-Walw5g14MXaMZrEGldUJMG2CfNC85AEjouT2kiYTR_MMzPWK2hE/s320/lpa-1700-2400.jpg" width="320" /></a></div><br />I employed Ye Olde Fashioned technique of carving an antenna out of double sided board with a ruler and a scalpel, using copper tape for little optimization experiments and fixing the mistakes. Once one has the hang of it, it is possible to carve an antenna by hand in a day, vs waiting two weeks for a PCB factory. <p style="text-align: left;"></p><p style="text-align: left;"></p><p>Etching it is good, if you have the chemicals and safety paraphernalia on hand and know what you are doing.</p><p>This application requires an aerial system with a few important properties, notably:</p><p style="text-align: left;"></p><ul style="text-align: left;"><li>Wide bandwidth of 20% or more with a centre frequency of 2 GHz. </li><li>Directivity of 8 to 12 dBi, to reduce clutter and interference from the surroundings, without making it difficult to point at the robotic vehicle.</li><li>Circular polarization when used in a high gain multi radiator array, to reduce multipath interference due to reflections off the earth surface.</li><li>Simple, repeatable and rugged construction, so it can be easily replicated and will not break during outdoor use in a harsh environment.</li></ul><p style="text-align: left;"></p><p style="text-align: left;"></p><p style="text-align: left;"></p><p style="text-align: left;">The above made me look at various PCB aerial topologies, including:</p><p style="text-align: left;"></p><ul style="text-align: left;"><li>Monopole</li><li>Patch</li><li>Tapered Slot </li><li>Log Periodic <br /></li></ul><p style="text-align: left;"></p>A PCB monopole aerial works very well, but it is inherently omnidirectional and and not easily stackable, so it is not great for ground use. It will be good as a blade antenna on an aircraft, so I will revisit this one.<br /><p style="text-align: left;"></p><p style="text-align: left;">A PCB patch aerial needs to be very thick, with air dielectric, assembled with nylon spacers and bolts, which makes it difficult to replicate. I made one like this once before - not recommended - much too fiddly.<br /></p><p style="text-align: left;">That left me with two well known ultra wide band antennas to explore for ground station use, the <i>Tapered Slot </i>and the <i>Log Periodic</i>. Both certainly will work well, if only I can get them tuned properly to the required band, which will take a few tries. <i>Patience, young padawan...</i><br /></p><h3 style="text-align: left;">Tapered Slot Aerial <br /></h3><p style="text-align: left;">A tapered slot traveling wave aerial proved to be quite amazing and it worked over 1 to 3 GHz. These type of aerials were designed half a century ago for use in radar sets and work very well at higher frequencies of several gigahertz. </p><p style="text-align: left;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiCaST53kGvtoVbhoVcqLFItMHgjszK9mntbz6jtm0u4TUuvobaSmOWlLCtvFJsYwTWeNW9ftccPTQQkh58ePSPkJwgmfi-ofizBvEKrmDOu7O9PrQSLCvKtGlzSCufxNEUb-FR3LCJ_GNSWJzbAnvzHTjy-wU678pyx7xmj6AiNHw4OnzntsJLg130NIk/s1420/tsa-1700-2400-top.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="651" data-original-width="1420" height="147" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiCaST53kGvtoVbhoVcqLFItMHgjszK9mntbz6jtm0u4TUuvobaSmOWlLCtvFJsYwTWeNW9ftccPTQQkh58ePSPkJwgmfi-ofizBvEKrmDOu7O9PrQSLCvKtGlzSCufxNEUb-FR3LCJ_GNSWJzbAnvzHTjy-wU678pyx7xmj6AiNHw4OnzntsJLg130NIk/s320/tsa-1700-2400-top.jpg" width="320" /></a></div><br />It is in effect a two dimensional horn antenna. The required band is at the lower end of its useful range and some experimentation was required to get a practical design.<p style="text-align: left;"></p><p style="text-align: left;"></p><p style="text-align: left;"><i></i></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhKiQzoLR_juANKFrqPMp55-9OTSQVTGqBJvw6F7EdkkubH1gaTQND-Kog9XP__M6No381NwPs1ucudQ9gGn4LOErmvYrCfyI-NaBMbqnG0O9Z21nwse-EzNK7EsNQjrFCtVmg2I33eLcbBRSu8q9n19JLv6L0XDoKl-PXNJqhV8xw0MJ_XAg5vcqvAYHE/s1512/return-loss.jpg" style="clear: left; float: left; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1046" data-original-width="1512" height="138" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhKiQzoLR_juANKFrqPMp55-9OTSQVTGqBJvw6F7EdkkubH1gaTQND-Kog9XP__M6No381NwPs1ucudQ9gGn4LOErmvYrCfyI-NaBMbqnG0O9Z21nwse-EzNK7EsNQjrFCtVmg2I33eLcbBRSu8q9n19JLv6L0XDoKl-PXNJqhV8xw0MJ_XAg5vcqvAYHE/w200-h138/return-loss.jpg" width="200" /></a><i></i></div><i><br />The prototype aerial has a forward gain of about 8 dBi. One can increase the gain by placing three antennas side by side (at 1.25
wavelength spacing). In a simple array, only drive the centre one, the
two parasites will squeeze the beam to 11 to 12 dBi - somewhat like a
Yagi aerial. <br /></i><p style="text-align: left;"></p><p style="text-align: left;">Using a power divider to drive two antennas, doesn't work any better than the above, since the divider, cables and connectors are lossy and a power divider is much more expensive than a third antenna!<br /></p><p style="text-align: left;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUDCxaLHExqtpAW3qE_jTP1wNf3BV-EyBzv5oi7y7m2urbRpO8EbBBddfmgHapQFyq9Emz5KAIGuZZmWrAL1J_mbou_92xA8WTXgYxl0D5j_dPUH-1Y9sy8whpnj4YnMlooamwkmY254evePcy5-uX2W5xBeBiFbmCkDgJBfCO08jYn8C9Ml2B0uTx6NA/s1512/vswr.jpg" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1008" data-original-width="1512" height="133" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUDCxaLHExqtpAW3qE_jTP1wNf3BV-EyBzv5oi7y7m2urbRpO8EbBBddfmgHapQFyq9Emz5KAIGuZZmWrAL1J_mbou_92xA8WTXgYxl0D5j_dPUH-1Y9sy8whpnj4YnMlooamwkmY254evePcy5-uX2W5xBeBiFbmCkDgJBfCO08jYn8C9Ml2B0uTx6NA/w200-h133/vswr.jpg" width="200" /></a></div><br />I ended up making a collection of test aerials of various shapes and sizes (<i>seven!</i>), measured them all and eventually settled on the following design rules related to the low end frequency <i>f1</i>, centre <i>fc</i> and high end <i>f2</i> (or <span lang="el"><i>λ1</i>, </span><span lang="el"><i>λc</i> and </span><span lang="el"><i>λ2</i>, for the chosen PCB substrate permittivity)</span>, with the tapered slot on the front and the microstripline feed on the back of the PCB and established the following rules of thumb:<p style="text-align: left;"></p><p style="text-align: left;"></p><ol style="text-align: left;"><li>Slot width (<i>Ws</i>), Infinitesimally small = 5 mil<br /></li><li>Microstrip width (<i>Wm</i>), 100 Ohm strip = 0.7 mm <br /></li><li>Microstrip taper to 50 Ohm (<i>Wc</i>) for the connector = 3 mm<br /></li><li>Slot stub radius (<i>Rs</i>), 0.19 of the centre wavelength = 13.6 mm<br /></li><li>Microstrip stub radius (<i>Rm</i>), 0.23 of the centre wavelength = 16.4 mm<br /></li><li>Slot opening width (<i>Wo</i>), 1.1 of the low end wavelength <i><span lang="el">λ</span>1</i> = 92.5 mm<br /></li><li>Tapered length (<i>Lt</i>), 3.5 times the centre wavelength <i><span lang="el">λ</span>c</i> = 250 mm<br /></li><li>Ground side width (<i>Gs</i>), 0.25 times the centre wavelength <i><span lang="el">λ</span>c</i> = 17.9 mm<br /></li><li>Ground back width (<i>Gb</i> ), 0.25 times the centre wavelength <i><span lang="el">λ</span>c</i> = 17.9 mm<br /></li><li>Substrate height (<i>h</i>), the design is not sensitive to the thickness, <i>FR4</i> = 1.6 mm<br /></li><li>Substrate relative permittivity (<i>Er</i>), a higher permittivity reduces the size of the aerial, <i>FR4</i> = 4.4</li></ol><p style="text-align: left;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjACnsIilL7ZhLhqGsI655FIno7kk1t9ohIHPJvwENskAs-qNU8ab4F9cZwwh0LmHzBbFxKqmzTyjx1eVnrLpkx38W56KVIJen_cjKT3NDGcoGKBNJK5lm3rxUtEhoUdvv4c0vUbM6KdrDIcrRPGxNZxObY3cCMzS_y8ScIyR4DadR_sp6lmCehbTG7mrg/s1368/taper-design.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="806" data-original-width="1368" height="189" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjACnsIilL7ZhLhqGsI655FIno7kk1t9ohIHPJvwENskAs-qNU8ab4F9cZwwh0LmHzBbFxKqmzTyjx1eVnrLpkx38W56KVIJen_cjKT3NDGcoGKBNJK5lm3rxUtEhoUdvv4c0vUbM6KdrDIcrRPGxNZxObY3cCMzS_y8ScIyR4DadR_sp6lmCehbTG7mrg/s320/taper-design.jpg" width="320" /></a></div><p style="text-align: left;"><br />The above simple straight tapered slot design will be good enough for most users. The slot is on the front of the board and the microstrip feed is on the back side. The electric field of the strip couples to the orthogonal magnetic field of the slot where they cross over - magic! </p><p style="text-align: left;">There are a few more optimizations that can be done, to reduce the size of the side lobes and eek out another 1 or two dB in forward gain. In general though, the main problem with this design is getting the low end frequency low enough, the high end takes care of itself. <br /></p><p style="text-align: left;"></p><p style="text-align: left;">A low frequency design cannot be made small - it has to be electrically large, so that <i>3.5 times <span lang="el">λ</span>c is the minimum length</i> and the <i>opening (mouth of the horn) must be larger than <span lang="el">λ</span>1</i>. The only way to reduce the size of the construction is to use a board with higher permittivity, which will also be slightly more lossy - there is no free lunch. </p><p style="text-align: left;">The quarter wave stubs are flared 90 degrees, to increase the bandwidth - these could also be circles - no performance difference. </p><p style="text-align: left;"><i>If the slot is electrically long, then the little opening will have an impedance of 100 to 130 Ohm</i>. For high power operation, one can solder a co-axial cable directly onto it and tune the radio for maximum smoke, or for low power operation, drive it with a matched impedance stripline on the other side of the board.</p><p style="text-align: left;">There are little optimizations that one can do with slots
and cut-outs, but the rule of diminishing returns apply and getting the
slots right is very time consuming, while getting them wrong can make it worse.<br /></p><p style="text-align: left;">An exponential flared slot (Vivaldi) looks cute and can make the antenna shorter by 10 to 20%, but the low frequency response then suffers, so there is much to be said for keeping the taper straight and simple.<br /></p><h3 style="text-align: left;">Log Periodic Aerial </h3><div style="text-align: left;">A problem with an ultra wide band antenna such as the tapered slot above, is that it could pick up significant out of band noise, which may desensitize the radio receiver. </div><div style="text-align: left;"> </div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIL8Ah_L3eAK0lhEfk-68iUJ6BHwOkbAeCOOXay3KOOo3wsw9O-0BWMrtv8C5-vM7Zq1jyDnarVU4Ibz_H4_MMoNvIvZ-geEUVkUPfEkhUUdpr2ZxnNaMZf3akjC9JnXL2oLES4TYyDWyel-m4eIfu99ZF8HyNWd6fGfj_DAvvoSEPHkX7fNoei3Jr2B0/s2663/lpa-1700-2400.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1486" data-original-width="2663" height="179" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIL8Ah_L3eAK0lhEfk-68iUJ6BHwOkbAeCOOXay3KOOo3wsw9O-0BWMrtv8C5-vM7Zq1jyDnarVU4Ibz_H4_MMoNvIvZ-geEUVkUPfEkhUUdpr2ZxnNaMZf3akjC9JnXL2oLES4TYyDWyel-m4eIfu99ZF8HyNWd6fGfj_DAvvoSEPHkX7fNoei3Jr2B0/s320/lpa-1700-2400.jpg" width="320" /></a></div><br /><div style="text-align: left;">It is not a problem if you are patrolling over the sea, or a desert, but over Europe, with cell phone towers galore, an antenna with less band width may be better, which lead me to a log periodic design. <div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4T_8zpDR62ynmMikglR4wYylB5z0obQmjh-5I0G_x2T4LXaDEx-kOAW5RSxONrQBcolfhIWHpoZr99G5h94ii7ebzw5wSV5FcJurRibCKiZ3fYY2RPiM-KYYC_a0pRbwPgbGlORB4tQDZZCA8r_LhgcBhc3OBu2KbpvrgAjHlAjzUHegIJ9Syah9GyGA/s2448/lpa-vswr.jpg" style="clear: left; float: left; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1603" data-original-width="2448" height="131" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4T_8zpDR62ynmMikglR4wYylB5z0obQmjh-5I0G_x2T4LXaDEx-kOAW5RSxONrQBcolfhIWHpoZr99G5h94ii7ebzw5wSV5FcJurRibCKiZ3fYY2RPiM-KYYC_a0pRbwPgbGlORB4tQDZZCA8r_LhgcBhc3OBu2KbpvrgAjHlAjzUHegIJ9Syah9GyGA/w200-h131/lpa-vswr.jpg" width="200" /></a></div></div><div style="text-align: left;"> </div><div style="text-align: left;">This type of antenna is easier to limit to the desired band. The six dipole elements will provide a forward gain slightly over 6 dBi.<br /></div><div style="text-align: left;"><br /></div><div style="text-align: left;">A stack of prototypes arrived from China and the VSWR plot showed that they are nicely band limited from 1700 to 2400 MHz.</div><div style="text-align: left;"></div><p style="text-align: left;"> </p><h3 style="text-align: left;">Antenna Patterns</h3><p style="text-align: left;">I made a couple of 2 GHz dipole antennas for reference (72 mm of thick copper wire) and used them to verify the antenna radiation patterns and gains. A dipole has a gain of 2 dB, so one can measure and convert dBd (relative to a dipole) to dBi (relative to isotropic). These type of measurements are very hard to do, due to radio and thermal noise. </p><p style="text-align: left;">Since I live in a little village outside the city, my test range is simply my back yard and a spectrum scan at 2 GHz confirmed that I do not need a shielded box - there is nothing out there. I could therefore set things up on a big wooden table and confirm that the antennas performed as expected.<br /></p><p style="text-align: left;"><i>The log periodic antenna has a forward gain of about 6 dB and a front to back ratio of about 25 dB</i>. The 3 dB beam width appears to be around + and - 20 degrees.</p><p style="text-align: left;"><i>The tapered slot antenna has a forward gain of about 8 dB</i> and a front to back ratio of about 25 dB. The 3 dB beam width is around + and - 15 degrees.</p><p style="text-align: left;"><i>Both of these antennas will certainly allow you to tune your Doodle Labs radio anywhere over the 1700 to 2400 MHz band without having to swap the antenna. Compared to a regular little stubby antenna, you should be able to fly your drone twice as far before going out of range, causing it to return home.</i></p><h3 style="text-align: left;">Range Extension</h3><p style="text-align: left;">For even longer range, a log periodic with 14 elements should be doable - if someone wants one, let me know. Otherwise, you could stack three antennas side by side, 216 mm apart and drive only the middle one. Leave the two outside parasitic antennas floating. That would give you another 3 dB gain. </p><p style="text-align: left;">Note that the more gain you have, the narrower the beam becomes and the more accurately you need to point the antenna array at the drone and therefore you may eventually want to look for an azimuth antenna rotator from SPID or Yaesu. <i>To track a UAV over long distance, you do not really need to rotate in elevation, unless you use an enormous parabolic dish reflector and even then it is not really necessary, since when you are close, the side lobes will connect.</i><br /></p><p style="text-align: left;">Normally, you should head for the hills with your ground station, but a five to ten meter mast, to elevate the antenna and radio above local obstructions, will do wonders. <br /></p><p style="text-align: left;">Also, don't point the antenna exactly horizontally. Rather slant it about 5 degrees up. That will reduce the influence of multi-path reflections off the ground. There is also an effect called tropo-scatter, so your radio may work over the horizon while pointed slightly up.<br /></p><h3 style="text-align: left;">FR4 PCB Properties - Er vs Eeff<br /></h3><p style="text-align: left;">FR4 PCB is as tough as an old tractor tyre and it has a permittivity of about <i>Er = 4.4</i> (or higher) at these frequencies, so it is a good practical choice for this aerial.<br /></p><p style="text-align: left;">One formula describes almost everything: <i><span lang="el">λ</span> = c / f sqrt(Er)</i></p><p style="text-align: left;">There are <i>stripline calculators</i> online at <i>Microwaves101</i> and <i>Pasternack</i> and of course as part of <i>KiCAD</i>, which may all be handy:</p><ul style="text-align: left;"><li><a href="https://www.microwaves101.com/calculators/1202-stripline-calculator">https://www.microwaves101.com/calculators/1202-stripline-calculator</a></li><li><a href="https://www.pasternack.com/t-calculator-stripline.aspx">https://www.pasternack.com/t-calculator-stripline.aspx</a></li></ul><p style="text-align: left;"> Here are stripline formulas that describe the rest:<br /></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiz_witSjwWQKw5cYtIR3oWuxldhsU0_VBV21T39_CE0qs5ehhRCK_clGthvkmVl6b8JAOqmv0B5oKZvv6qq5awGCBlU1KAH2F0yc77iAlnoZHCKVdit0u1B5AQISqhHwhn1wIsSbd6ERutioi7tpgQiZPXWcbOuj7dGhXTXyb03sOKvwXlXGvSGyVVqQM/s2192/StriplineFormulas.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="946" data-original-width="2192" height="138" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiz_witSjwWQKw5cYtIR3oWuxldhsU0_VBV21T39_CE0qs5ehhRCK_clGthvkmVl6b8JAOqmv0B5oKZvv6qq5awGCBlU1KAH2F0yc77iAlnoZHCKVdit0u1B5AQISqhHwhn1wIsSbd6ERutioi7tpgQiZPXWcbOuj7dGhXTXyb03sOKvwXlXGvSGyVVqQM/s320/StriplineFormulas.png" width="320" /></a></div><p style="text-align: left;">The last formula above is interesting, since it is possible to measure the effective permittivity <i>Eeff</i> with a VNA, to confirm that it actually is what it is thought to be and then convert it to the bulk relative permittivity <i>Er</i> after a bit of algebraic formula massaging you will find that <i>Eeff = 0.64 x Er + 0.36 for a surface stripline.<br /></i></p><p style="text-align: left;">Note that: <i>1
< Eeff < Er, because with a stripline, >half the electrical
field goes through air and <half through the substrate.</i> <br /></p><p style="text-align: left;"></p><p style="text-align: left;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgUw2BxRYDzQVfbjEkrMqoDqECj3hbPk5rv_ZPGGM64VzP9qKRR7cWg6j_L5qpVO20v9pLUX0u6rUZ8M47ivuA9YQT1lcEThIZnqKV0dklJMJhAPy3UM9U_w06zGYgnlJ76ERHzJmhqWSstof2aJOMeKiGR8ecHh7Hgzws8859ByrApjHJb3-GtBZiwf9c/s1512/Rogers-Stripline.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="459" data-original-width="1512" height="97" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgUw2BxRYDzQVfbjEkrMqoDqECj3hbPk5rv_ZPGGM64VzP9qKRR7cWg6j_L5qpVO20v9pLUX0u6rUZ8M47ivuA9YQT1lcEThIZnqKV0dklJMJhAPy3UM9U_w06zGYgnlJ76ERHzJmhqWSstof2aJOMeKiGR8ecHh7Hgzws8859ByrApjHJb3-GtBZiwf9c/s320/Rogers-Stripline.jpg" width="320" /></a></div>If
one would make a long stripline on a piece of scrap PCB and solder a
connector on one end only, leaving the other end open, then carefully
calibrate the VNA and go to the Phase plot, the energy will reflect back
from the far end and one will see standing waves with a sequence of
zero crossings, for each harmonic. At the first crossing, the
wavelength at that exact frequency is <i>2L</i> and then <i>Eeff = (c / 2 L f)^2, </i>which for FR4 is about <i>Eeff = 3.17<br /></i><p style="text-align: left;"></p><p style="text-align: left;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhBMEJ12gXtBr_1Dfda2HZstwYRwMeJOFz9mcGLBjj1MEjeukJOBfskLWnW_bIdrwp1iQoIOQv4xHcVnq0TRGJo6gJEawhLSf0bxD05tUsWaH3tnaUTO2WW0bEXa4AStOja_VpM2gkLYNMx5JMJeyYJpdEaonrDhEq6YJYMGdsx089qXG4AwM7p9-pCE_Y/s640/phase-standing-waves.jpg" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="488" data-original-width="640" height="153" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhBMEJ12gXtBr_1Dfda2HZstwYRwMeJOFz9mcGLBjj1MEjeukJOBfskLWnW_bIdrwp1iQoIOQv4xHcVnq0TRGJo6gJEawhLSf0bxD05tUsWaH3tnaUTO2WW0bEXa4AStOja_VpM2gkLYNMx5JMJeyYJpdEaonrDhEq6YJYMGdsx089qXG4AwM7p9-pCE_Y/w200-h153/phase-standing-waves.jpg" width="200" /></a></div><p style="text-align: left;">The
problem with the straight stripline above, is that you don't know
exactly where to measure the length from - the tip of the SMA connector
is the best, but this test setup is bound to be inaccurate. It will
give a good idea about the permittivity of an unknown board, but a
better way to do it, is to make a circle and excite that through a small
capacitor (a tiny gap). One can calculate the circumference of the
circle easily enough and then one will have a more accurate measurement
of <i>Eeff</i> and the <i>Er</i> of <i>FR4</i> will be just about <i>Er = 1.39 x Eff</i></p><p style="text-align: left;">Similarly the Velocity Factor for a surface track on FR4 is about <i>Vf = 1/sqrt(Eeff) = 1/sqrt(3.17) = 0.56 </i><br /></p><p style="text-align: left;"></p><h3 style="text-align: left;">A Matter of Scale <i><br /></i></h3><p style="text-align: left;">The <i>Velocity Factor Vf</i>
is important to scale an air wire antenna design to a PCB with
dielectric on one side of the tracks, then all the wire dipole elements
become shorter by <i>0.56</i>. A more obscure effect is the velocity factor for the <i>space between</i> <i>elements</i>
of an array antenna (where there is no copper, only dielectric) as for a
PCB Yagi or Log Periodic made on the surface of a FR4 PCB, is about <i>0.8</i>. </p><p style="text-align: left;"><i>Therefore
a FR4 PCB antenna is much narrower (60%) and only somewhat shorter
(80%), compared to an equivalent air wire antenna. It took me ages to
figure this out!</i><br /></p><h3 style="text-align: left;"></h3><h3 style="text-align: left;">Production<br /></h3><p style="text-align: left;">I sketched the designs with the <i>KiCAD</i> footprint editor and since wide band antenna designs are not super sensitive to the exact PCB properties, I ordered prototypes from <i>Dirtypcbs</i> (<a href="https://dirtypcbs.com/store/pcbs">https://dirtypcbs.com/store/pcbs</a>) in Hong Kong.</p><p style="text-align: left;">Both designs work remarkably well. I only need to improve the aesthetics of the solder masks and silk screens.<br /></p><p style="text-align: left;"></p><p style="text-align: left;">If you want one or two (or ten thousand!), send me a message and I will let you know when the designs are final.</p><h3 style="text-align: left;">Costing</h3><p style="text-align: left;">Hobby users can buy one or two at cost, for 30 Euro each plus shipping - about another 30 Euro for courier charges.</p><p style="text-align: left;"><i>Business users can buy the KiCAD design files for 3000 Euro, customize it, change the outline and mounting holes, all without involving me and go make as many as you want.</i><br /></p><p style="text-align: left;">Invoicing and payment is through <i>Paypal</i>. <br /></p><p style="text-align: left;">La voila!</p><p style="text-align: left;">Herman</p><p style="text-align: left;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgIrYbGge5MRn3-TYAt7LWJkyBE_WliFW4CnZ_a9elbftUEbKCTPJbBWdDk2GqPHwPGUIPP_vt2e4dw0zLq4CHeaaTQg_HIw3UaANFTtk2JCyoGL-TO044L8gElsi_HoVK_5K8jJn2fGP_Ax3qt8-ZhwnNGFa6P77G-xabBZMx6R2wTwOMLotuNsspbWgs/s306/Email-Phone.png" style="clear: left; float: left; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="68" data-original-width="306" height="44" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgIrYbGge5MRn3-TYAt7LWJkyBE_WliFW4CnZ_a9elbftUEbKCTPJbBWdDk2GqPHwPGUIPP_vt2e4dw0zLq4CHeaaTQg_HIw3UaANFTtk2JCyoGL-TO044L8gElsi_HoVK_5K8jJn2fGP_Ax3qt8-ZhwnNGFa6P77G-xabBZMx6R2wTwOMLotuNsspbWgs/w200-h44/Email-Phone.png" width="200" /></a></p><p style="text-align: left;"><br /></p><p style="text-align: left;"><br /></p><p style="text-align: left;"><br /></p><p style="text-align: left;"><br /></p><br />Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com0tag:blogger.com,1999:blog-1589959253862674712.post-69640028676155392862024-02-07T12:46:00.048+01:002024-02-11T22:39:38.605+01:00OpenEMS with Octave and SciLAB<div><h2 style="text-align: left;"></h2><p style="text-align: left;">I wanted to do some advanced RF antenna development work and needed an electromagnetic field solver that is a bit more up to date than <i>NEC2</i>. Commercial solvers from <i>Matlab</i>, <i>Ansys</i> and others are hideously expensive (in the order of $20,000 to $50,000) and do not fit in the wallet of a hobbyist or a small consulting company. Recently, <i>openEMS</i> became available and it fills the niche with a capable free tool. </p><p style="text-align: left;">In general, <i>openEMS</i> is a solver - a Finite-Difference Time-Domain (FDTD) numerical engine. You interact with it through <i>Octave</i>, which is almost identical to <i>Matlab</i>. You can watch a good video by <i>Thorsten Liebig</i> here: <a href="https://www.youtube.com/watch?app=desktop&v=ThMLf0d5gaE">https://www.youtube.com/watch?app=desktop&v=ThMLf0d5gaE</a></p><p style="text-align: left;"> <img alt="" border="0" class="thumbimage" height="202" src="https://wiki.openems.de/images/thumb/d/d7/Helical_Antenna_RadPattern.png/400px-Helical_Antenna_RadPattern.png" width="400" /></p><p style="text-align: left;">Getting it to work is a little painful, but it is free, so bear with it - then <i>save a backup clone, or a zipped copy of the whole virtual machine directory</i> and <i>NEVER</i> update it, to ensure that it keeps going and doesn't get broken by future updates, right when you are in the middle of something important and working against a deadline...<br /></p><h3 style="text-align: left;">Virtualbox/VMWare with Devuan Linux </h3><p style="text-align: left;"></p><p style="text-align: left;">The easiest way to install <i>openEMS</i> (<a href="https://www.openems.de">https://www.openems.de</a>) with <i>Octave</i> and <i>SciLAB</i> on any computer system, even my 12 year old Macbook Pro, is to install <i>VMWare</i> (<a href="https://www.vmware.com/products/workstation-player.html">https://www.vmware.com/products/workstation-player.html</a>), or <i>Virtualbox</i> (<a href="https://www.virtualbox.org/">https://www.virtualbox.org/</a>), then download and install <i>Devuan</i> Linux (<a href="https://www.devuan.org">https://www.devuan.org</a>) and install <i>OpenEMS</i>, <i>Octave</i> (<a href="https://octave.org">https://octave.org</a>) and <i>Scilab</i> (<a href="https://www.scilab.org">https://www.scilab.org</a>) from the repositories. <br /><br /><i><b>Devuan is the best UNIX version for scientific and engineering use by far! </b></i><br />(Sadly, <i>Ubuntu</i>, <i>Fedora</i> etc. have become middle aged, bloated and slow and do not work very well in a virtual machine anymore)</p><p style="text-align: left;">Download <i>Devuan <b>Chimaera</b> Desktop Live AMD64</i> from here: <a href="https://www.devuan.org/get-devuan#https-mirrors">https://www.devuan.org/get-devuan#https-mirrors</a></p><p style="text-align: left;">Installing <i>Virtualbox</i> and making a virtual machine is a pain in itself, but I am not going to go into that here. Even though I have been using <i>Virtualbox</i> for decades and done this hundreds(?) of times, I still had to try three times to get <i>Devuan</i> installed and running, so it needs a nice cuppa and some patience, possibly mixed with a healthy side of <a href="https://www.google.com/">googling</a> (Put <i>linux</i> as the first word of any search to cut the cruft).<br /></p><p style="text-align: left;">Once <i>Devuan</i> is up and running, upgrade Linux to the latest security version:<br /><i>$ su -<br />password<br /># apt update<br /># apt dist-upgrade</i><br /><br />BTW I prefer having a normal root user <i>and</i> sudo - it is one of the install options of <i>Devuan</i> - therefore the "<i>su -</i>" trick. I just don't like typing <i>sudo</i> all the time.<br /></p><p style="text-align: left;">If you cannot automatically get into the live <i>Devuan</i> system, log in with <i>root</i> and password <i>toor</i>. The next time you restart it, it should log in automatically. The default user is <i>devuan</i> with password <i>devuan</i>.<br /></p><p style="text-align: left;">If you get <i>repository security change</i> trouble, you may need to do:<br /><i># apt --allow-release-info-change update</i></p><h3 style="text-align: left;"><i>Virtualbox Guest Additions</i><br /></h3><div style="text-align: left;">Once you have a Devuan virtual machine installed up and running, install the <i>Virtualbox Guest Additions</i>:</div><div style="text-align: left;"><i>Click Devices, Insert Guest Additions CD Image,</i> then open a file browser and click on the Guest additions device at the bottom left <i>Select Open a Terminal Here.</i></div><div style="text-align: left;"><i> </i></div><div style="text-align: left;">Run:</div><div style="text-align: left;"><i>$ sudo ./VBoxLinux[Tab]...</i></div><div style="text-align: left;"> </div><div style="text-align: left;">Now exit and restart the <i>Devuan</i> virtual machine to activate a smooth running GUI with the use of a <i>shared clipboard</i>, to make it easy to copy things between the guest and host. </div><h3 style="text-align: left;">Guest Power Management <br /></h3><div style="text-align: left;">Finally, run the <i>Settings Power Manager</i> utility and turn all power management and go to sleep features off on battery and plugged in: <i>Slider Left = Never</i>. The host computer will manage the power, the guest will just mess things up, go to sleep and never wake up, requiring a guest power cycle - best avoided.<br /></div><h3 style="text-align: left;">OpenEMS Status on Devuan Daedalus<br /></h3></div><div style="text-align: left;">The <i>openEMS</i> package was not built and installed right, so one has to rebuild it from source, which is described here: <i>https://wiki.openems.de/index.php/Compile_from_Source.html</i>, but which first need the C compiler and development tools installed. (It always amazes me when people develop code on Linux, for Linux, but it only works out of the box on Windows!) </div><div style="text-align: left;"> </div><div style="text-align: left;">I tried to build <i>openEMS</i> from source on <i>Daedalus</i>, but ran into issues with the dependent libraries, so I went one version back to <i>Devuan</i> <i>Chimaera</i>, where <i>openEMS</i> from the repositories is <i>also</i> not installed right, but it compiles successfully from source as described in the manuals, with only one or two hiccups, so do follow my instructions below, while also looking at the manuals. <i> </i></div><div style="text-align: left;"><i> </i></div><div style="text-align: left;"></div><div style="text-align: left;">The saga continues...<br /><h3>Install Devuan Development Tools</h3><div style="text-align: left;">To install the development tools on <i>Devuan</i>, do the following:</div><div style="text-align: left;"><i>$ su -</i></div><div style="text-align: left;"><i>toor </i><br /></div><div style="text-align: left;"><i># apt update</i></div><div style="text-align: left;"><i># apt install build-essential</i></div><div style="text-align: left;"> </div><div style="text-align: left;">Now one should be able to pull <i>openEMS</i> from <i>Github</i>, compile and install it.<br /></div><h3>Build openEMS from Source on Devuan Chimaera<br /></h3><div style="text-align: left;">The <i>openEMS</i> build and install process is described here:</div><div style="text-align: left;"><i>https://docs.openems.de/install.html </i></div><div style="text-align: left;"><i><br /></i></div>Get the <i>openEMS</i> dependency files:<div style="text-align: left;"><i>$ su -</i></div><div style="text-align: left;"><i>toor<br /></i></div><div style="text-align: left;"><i># apt install build-essential cmake git libhdf5-dev libvtk7-dev libboost-all-dev libcgal-dev libtinyxml-dev qtbase5-dev libvtk7-qt-dev</i></div></div><div style="text-align: left;"></div><div style="text-align: left;"><i># apt install octave liboctave-dev<br /># apt install gengetopt help2man groff pod2pdf bison flex libhpdf-dev libtool</i></div><div style="text-align: left;"><i> </i></div><div style="text-align: left;"><i>(The next line is not in the manual) <br /></i></div><div style="text-align: left;"><i># apt install pip <br /></i></div><div style="text-align: left;"><i># pip install numpy matplotlib cython h5py</i><br /><br />Clone the repository, build and install in <i>/home/devuan/opt</i>, to keep it separate from the broken version in <i>/bin</i>, so it won't get overwritten during a Linux update.</div><div style="text-align: left;"> </div><div style="text-align: left;"><i>As the devuan user (not root!) do the following (watch for errors!):</i> <br /></div><div style="text-align: left;"><i>$ git clone --recursive https://github.com/thliebig/openEMS-Project.git</i></div><div style="text-align: left;"><i>$ cd openEMS-Project</i></div><div style="text-align: left;"><i>$ ./update_openEMS.sh ~/opt/openEMS</i></div><div style="text-align: left;"><i>(Alternatively leave out the tilde in the above command and it will go into /opt which is maybe better, but I don't want to deviate from the recommended path now, since it may cause issues with the tutorials. Leave it for another day) </i><br /><h3 style="text-align: left;">Configure Octave <br /></h3><div style="text-align: left;">If you see: <i>"OpenEMS and all modules have been updated sucessfully"</i>, add the required paths to <i>Octave</i>/<i>Matlab</i>:<br /><i>addpath('/home/devuan/opt/openEMS/share/openEMS/matlab')<br />addpath('/home/devuan/opt/openEMS/share/CSXCAD/matlab')</i></div><div style="text-align: left;"><br />You can setup these above paths using the <i>“Edit”-Menu, “Set Path”</i> in <i>Octave</i>. </div><div style="text-align: left;"> </div><div style="text-align: left;">Run <i>octave</i> the <i>first time</i> from the command line (to auto configure some things) and <i>exit</i> it, then run it from the menu under <i>Education</i>. If you just click the menu item, seemingly nothing will happen, until you despair and run it from the command line to check for error messages and then it will magically work. Don't ask me why!<br /></div><div style="text-align: left;"> </div><div style="text-align: left;">Add <i>openEMS</i> to the <i>devuan</i> user search path:</div><div style="text-align: left;"><i>export PATH=”$HOME/opt/openEMS/bin:$PATH”</i></div><h3 style="text-align: left;">Test It <br /></h3><div style="text-align: left;">See this, and do <b><i>ALL</i></b> the Linux tests to confirm that it really works as it should: <i><a href="https://docs.openems.de/install/check.html#check-installation-src">https://docs.openems.de/install/check.html#check-installation-src</a></i><br /></div><div style="text-align: left;"> </div><div style="text-align: left;">If you have no idea how <i>Octave</i> works, google for <i>Octave beginner tutorials</i>, such as this: <a href="http://www-mdp.eng.cam.ac.uk/web/CD/engapps/octave/octavetut.pdf">www-mdp.eng.cam.ac.uk/web/CD/engapps/octave/octavetut.pdf</a><br /></div><div style="text-align: left;"> </div><div style="text-align: left;">If you still have problems, the <i>Octave</i> setup is described here: <br /></div><div style="text-align: left;"><div style="text-align: left;"><i><a href="https://docs.openems.de/octave/install.html#octave-linux-install">https://docs.openems.de/octave/install.html#octave-linux-install</a> </i></div><div style="text-align: left;"><i> </i></div><div style="text-align: left;">Congratulations, you are now allowed to grow an<i> Official Linux Guru Beard :)</i></div><div style="text-align: left;"><i> </i></div><div style="text-align: left;"><i>...and don't forget to send a Thank You message to Thorsten Liebig! </i><br /></div></div><h3>Other EM Utilities</h3>I also installed <i>kicad </i>(<a href="https://www.kicad.org/">https://www.kicad.org/</a>)<i>, xnec2c</i> (<a href="https://www.xnec2c.org/">https://www.xnec2c.org/</a>) for my RF hobby/work as well as <i>gimp</i> and <i>inkscape</i> to edit PCB footprint drawings and sometimes <i>meshlab</i>. The tutorials showed that <i>paraview</i> is also needed to view <i>.vtr</i> files.</div><div style="text-align: left;"><br /></div><div style="text-align: left;">Here you go:<br /></div><div style="text-align: left;"><i>$ su -</i></div><div style="text-align: left;"><i>toor</i></div><div style="text-align: left;"><i># apt install kicad xnec2c gimp inkscape meshlab paraview</i><br /></div><h3 style="text-align: left;">Getting to work <br /></h3><div style="text-align: left;">Finally, go to the <i>openEMS</i> tutorials (<a href="https://wiki.openems.de/index.php/Tutorials.html">https://wiki.openems.de/index.php/Tutorials.html</a>), start at the top and work your way to the bottom. That will keep you out of trouble for a while, especially since there are some syntax errors in the tutorial scripts that you will have to find, single step and fix in the <i>Octave</i> editor... :)<br /></div><p style="text-align: left;"><i>Crikey, now I need a long weekend to recover from this!</i><br /></p><p style="text-align: left;">La voila!<br /><br />Herman</p>Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com0tag:blogger.com,1999:blog-1589959253862674712.post-45385162411005116352023-10-04T09:57:00.012+02:002023-10-05T19:55:14.840+02:00Earth Observation Satellite 1700 MHz Patch Antenna<p>The L-Band is carved up for many services and the 1690 to 1710 MHz Space to Earth band is shared with 4G cell phone services, with several geo stationary and polar orbit earth observation satellites operating at <a href="https://www.ntia.doc.gov/files/ntia/publications/compendium/1695.00-1710.00_01DEC15.pdf">1702.5 and 1707 MHz</a>. Since I recently made an <a href="https://www.aeronetworks.ca/2023/09/rf-controlled-impedance-pcb.html">ADS-B 1090 MHz patch</a> I decided to make one for this higher frequency band, while I am still in the swing of things with my <i>mad antenna carving skillz</i>.</p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgnz6e6qNgSW2I1_IbpM0rz6_FOUw0W-9BsBc1oXb98DPtxiq8sflEkkEAudQWeXJXfxtnXuPyHXBnKyU7in4JjHeuPllCuTG-lMBdAvjx6swkGrrzCW5PLbvNwJN6VFOjuodV37eWmFfr4ossjh7Oz3xEkwWIyyvzsgoDdUYg0vYQ98x4XT4cvcH8VQ6E/s206/JPSS-Patch-1700.png" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="166" data-original-width="206" height="166" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgnz6e6qNgSW2I1_IbpM0rz6_FOUw0W-9BsBc1oXb98DPtxiq8sflEkkEAudQWeXJXfxtnXuPyHXBnKyU7in4JjHeuPllCuTG-lMBdAvjx6swkGrrzCW5PLbvNwJN6VFOjuodV37eWmFfr4ossjh7Oz3xEkwWIyyvzsgoDdUYg0vYQ98x4XT4cvcH8VQ6E/s1600/JPSS-Patch-1700.png" width="206" /></a></div>This Right Hand Circular polarized antenna is carved from <i>Rogers RO4350B</i> low loss PCB and after a couple days of meticulous cutting and measuring it is spot on.<br /><p></p><p><i>It is amazing what one can make if one has enough coffee, chocolate and patience!</i></p><p><i>Rogers 4350B</i> copper clad circuit board has the following RF parameters:</p><ul style="text-align: left;"><li>Permittivity <i>Dk</i> = 3.66</li><li>Loss <i>Df</i> = 0.0031 </li><li>Dielectric width <i>Dw</i> = 0.508 mm</li><li>Cu 1 Oz = 36 um </li></ul><p>This <i>Joint Polar Satellite Service</i> (JPSS) antenna has the following dimensions:</p><ul><li><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiiGi5LBCB0Nsp0ZEu5EiXg5rzo-0FdCbWDeu2P1x38hhNMzxIbj-wphUHC-QeCmePKqKeWuTiFsJUBVb89XkQis7IwLBLKd-XUUdFVTMk2SzyErtDHGwc9uPpfJWpT_21ROVzZ40zwTbXlniAgbQqNpiEF0dGPcLYJ6bg928UWH7-t-0FiynjIarC4TAI/s2016/1700MHz-VSWR.jpg" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1512" data-original-width="2016" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiiGi5LBCB0Nsp0ZEu5EiXg5rzo-0FdCbWDeu2P1x38hhNMzxIbj-wphUHC-QeCmePKqKeWuTiFsJUBVb89XkQis7IwLBLKd-XUUdFVTMk2SzyErtDHGwc9uPpfJWpT_21ROVzZ40zwTbXlniAgbQqNpiEF0dGPcLYJ6bg928UWH7-t-0FiynjIarC4TAI/s320/1700MHz-VSWR.jpg" width="320" /></a></div>Base: 69 x 54.6 mm</li><li>Patch: 53.3 x 43.4 mm</li><li>Corners: 12 x 12 mm</li><li>Slots: 5 x 8 mm</li><li>Feed: 1.1 x 7.5 mm</li></ul><p></p><br />A receive antenna does not have to be super accurate, but <i>0.1 mm makes a measurable difference</i>. If you have very steady hands, a sharp scalpel, calipers and a reasonable quality Vector Network Analyzer, then you can carve one of your own and see what you get, or you can send me a message and once there are multiple takers, I'll have a batch made at <i>Eurocircuits,</i> next door in Hungary.<p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgIrYbGge5MRn3-TYAt7LWJkyBE_WliFW4CnZ_a9elbftUEbKCTPJbBWdDk2GqPHwPGUIPP_vt2e4dw0zLq4CHeaaTQg_HIw3UaANFTtk2JCyoGL-TO044L8gElsi_HoVK_5K8jJn2fGP_Ax3qt8-ZhwnNGFa6P77G-xabBZMx6R2wTwOMLotuNsspbWgs/s306/Email-Phone.png" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="68" data-original-width="306" height="44" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgIrYbGge5MRn3-TYAt7LWJkyBE_WliFW4CnZ_a9elbftUEbKCTPJbBWdDk2GqPHwPGUIPP_vt2e4dw0zLq4CHeaaTQg_HIw3UaANFTtk2JCyoGL-TO044L8gElsi_HoVK_5K8jJn2fGP_Ax3qt8-ZhwnNGFa6P77G-xabBZMx6R2wTwOMLotuNsspbWgs/w200-h44/Email-Phone.png" width="200" /></a></div><br /><p><br /></p><p>La voila!</p><p>Herman <br /></p>Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com0tag:blogger.com,1999:blog-1589959253862674712.post-9603764574740458532023-09-20T16:48:00.011+02:002023-10-25T10:38:03.147+02:00Weather Satellite VHF LNA<p><i>Minikits</i> in Australia (<a href="https://www.minikits.com.au/">https://www.minikits.com.au/</a>) makes a nifty little low noise RF amplifier for a VHF weather satellite receiver, such as the <a href="https://www.rtl-sdr.com/m2_lrpt_decoder-version-59-released/"><i>Meteor</i></a> satellite on 137 MHz. <i>Note that <a href="https://www.satdump.org/posts/basic-usage/">SatDump</a> is very much improved now - it is all the software you need to see that it is raining outside, without the stress of looking out the window.</i><br /></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgecSHQkXPooVaNa112bayh8e4I6c1FDs_TcYpvd4Zgk6oZ2FHrUWCdPXRvpbAv4RH_m1lUwHHL1V-m-jXSbgKbfKavn0641XMWq7uBJHH_lrDz8l6K_k4uFmk_Ys_7GYOR23DvXEaPLJo3TVXvgNCG7tWISb1YLspAZQxzTAEWW5YNQkJgjWhR6TWhFHk/s2267/VHF-LNA-HW.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1251" data-original-width="2267" height="177" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgecSHQkXPooVaNa112bayh8e4I6c1FDs_TcYpvd4Zgk6oZ2FHrUWCdPXRvpbAv4RH_m1lUwHHL1V-m-jXSbgKbfKavn0641XMWq7uBJHH_lrDz8l6K_k4uFmk_Ys_7GYOR23DvXEaPLJo3TVXvgNCG7tWISb1YLspAZQxzTAEWW5YNQkJgjWhR6TWhFHk/s320/VHF-LNA-HW.jpg" width="320" /></a></div><p>Some careful soldering is required, but it is not difficult to build. When I test an RF circuit, I run it from a <i>12V sealed battery - my noise free power supply</i>.</p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEggCPuuYHxrdU7zwZ8sVgRI1GvInk7UNUJj818Of_QGCTX-BMvIP-fI7rynnip85Hsc-tGaDIGrpsDgSm0KVbtv81zMtEn5kg43YUGMTg92Q60XveL2Y-pdYulP1p2EfS_M6p0s_YviqQpO1FoqvBP-MCD-ylIFVd09ag8TRZU5rL742_JmlgkBjJmJ81A/s1954/VHF-LNA-Gain.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1329" data-original-width="1954" height="218" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEggCPuuYHxrdU7zwZ8sVgRI1GvInk7UNUJj818Of_QGCTX-BMvIP-fI7rynnip85Hsc-tGaDIGrpsDgSm0KVbtv81zMtEn5kg43YUGMTg92Q60XveL2Y-pdYulP1p2EfS_M6p0s_YviqQpO1FoqvBP-MCD-ylIFVd09ag8TRZU5rL742_JmlgkBjJmJ81A/s320/VHF-LNA-Gain.jpg" width="320" /></a></div><p></p><p>Once tuned up carefully with a nylon screwdriver (<i>the little spatula that you get with epoxy glue!</i>), it can provide up to 20 dB gain, but on average over the band, expect about 5 to 10 dB. With some patience I eventually managed to eek out <i>7.6 dB at 137 MHz</i>. This may not sound like a lot, but a radio receiver is more dependent on the <i>Signal to Noise and Distortion Ratio</i> (<i>SINAD</i>), than the actual signal level.<br /></p><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhwEjfqaBLbGZ4aDaCxV2_sDm05qWTkboPwb-Qiciz0dyqmeQl-rxlZDMcthIRZ-fVa-g59ZQMgMSrByVjJk10GSbHS9FPnjtKxnoxlnppSaa078X-xXyU1yMqk8Ic8HJ-SyKTo2WSmAuk1xB_aaP4hIXqSNZ0-CCJXhm7K4ZknS02tvGtTBz44rT5w694/s2016/IMG_0457.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2016" data-original-width="1512" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhwEjfqaBLbGZ4aDaCxV2_sDm05qWTkboPwb-Qiciz0dyqmeQl-rxlZDMcthIRZ-fVa-g59ZQMgMSrByVjJk10GSbHS9FPnjtKxnoxlnppSaa078X-xXyU1yMqk8Ic8HJ-SyKTo2WSmAuk1xB_aaP4hIXqSNZ0-CCJXhm7K4ZknS02tvGtTBz44rT5w694/s320/IMG_0457.jpg" width="240" /></a></div><p></p><p>The LNA is a tuned single transistor amplifier with a linear power supply and a bias-T circuit, which is just the job for a weather sat.</p><p> </p><p>Also see these: </p><ul style="text-align: left;"><li><a href="https://www.aeronetworks.ca/2017/12/amateur-satcom-rx-antenna-for-2-meter.html">https://www.aeronetworks.ca/2017/12/amateur-satcom-rx-antenna-for-2-meter.html</a></li><li><a href="https://www.aeronetworks.ca/2017/12/satellite-weather-maps-on-macbook.html">https://www.aeronetworks.ca/2017/12/satellite-weather-maps-on-macbook.html </a></li><li><a href="https://satnogs.org/">https://satnogs.org/</a> </li><li><a href="https://usradioguy.com/meteor-m2-3/#V59">https://usradioguy.com/meteor-m2-3/#V59</a></li><li><a href="https://github.com/happysat/Setup-Meteor-M-N2-3-with-LRPT-Decoder-and-MeteorGIS/blob/main/README.md">https://github.com/happysat/Setup-Meteor-M-N2-3-with-LRPT-Decoder-and-MeteorGIS/blob/main/README.md</a></li><li><a href="https://www.satdump.org/posts/basic-usage/">https://www.satdump.org/posts/basic-usage/</a> </li></ul><p> <br /></p><p>La Voila!</p><p>Herman <br /></p><p><br /></p>Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com0tag:blogger.com,1999:blog-1589959253862674712.post-5965763183390793932023-09-07T12:38:00.048+02:002023-10-10T09:17:03.694+02:00ADS-B Patch Antenna on RF Controlled Impedance PCB<p>In a moment of boredom/inspiration, I thought about making a patch antenna for my <a href="https://www.aeronetworks.ca/2023/01/ads-b-quarter-wave-whip-antenna.html"><i>ADS-B aircraft tracking</i></a> system, which is part of <a href="https://globe.adsbexchange.com/">ADS-B Exchange</a>. One can make one-off patch antennas from garden variety glass/epoxy FR4 board, but the result will have relatively high loss and it will not be repeatable. In order to simply order high quality batches of antennas from any PCB factory, one needs to use <i>low loss,</i> <i>controlled impedance board stock</i>.</p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsy7F4GunZ_l8LwMMtq1e4ZDFbKyE5ltD6T8zmVsAIhdlfQo5MiDw0JcT002m4_BttBn8lm8oQgek6ukU_Ft03kCDR7MeprSnHUKu7BjHIl84Dk-L7HZI2o2jCTitVG4fbk8a-O_QzSjkaytfzV6R2ESKaH1gAd_BtE9B1bdLShvG73KOR2luawGVfnks/s1026/Screen%20Shot%202023-10-01%20at%207.35.08%20PM.png" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="820" data-original-width="1026" height="256" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsy7F4GunZ_l8LwMMtq1e4ZDFbKyE5ltD6T8zmVsAIhdlfQo5MiDw0JcT002m4_BttBn8lm8oQgek6ukU_Ft03kCDR7MeprSnHUKu7BjHIl84Dk-L7HZI2o2jCTitVG4fbk8a-O_QzSjkaytfzV6R2ESKaH1gAd_BtE9B1bdLShvG73KOR2luawGVfnks/s320/Screen%20Shot%202023-10-01%20at%207.35.08%20PM.png" width="320" /></a></div>With this antenna, the ADS-B receiver simply sits on my window sill and picks up aircraft 200 km away.<br /><p></p><h3 style="text-align: left;">Cut Corners <br /></h3><p>The design is a typical rectangular patch antenna, with circular polarization. A circular polarized antenna allows more mounting options for a conformal antenna. <br /></p><p></p><p></p><h3 style="text-align: left;">Slots <i><br /></i></h3><p><i>The side slots in this design increases the bandwidth, but it also reduces the operating frequency, so slots can be used to tune a patch antenna design.</i></p><h3 style="text-align: left;">Board Type <br /></h3><p>There are a variety of RF boards made by various manufacturers (<i><a href="https://rogerscorp.com/">Rogers</a>, <a href="https://www.isola-group.com/">Isola</a>, <a href="https://industrial.panasonic.com/ww/electronic-materials/products/cbm">Panasonic</a>...</i>) and the RF parameters are different, therefore once you designed your spiffy new antenna for <i>Rogers 4003C</i>, then you cannot change your mind and manufacture it from <i>Isola I-Tera MT40</i> - you need a new design.</p><p></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg5OB9bTgyrl2y5gxJS2YB3_32U9VtOT3X314S60XYb9s7bnbQGl-sRwBVJE7mXeBV4WUzBG6NRxZP1KmONU0pxUSTNxXDPS57JAUY2ZW0HgM12zO-Y0fc8cXhx-yMyqDc7NhYChTkzKxNIJHIMW3BFDV8T-_Y_-iS05nF_WbDGEiDjgpix8tIe7ahE8SQ/s2048/ADS-B-Receiver.jpg" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="2048" data-original-width="1152" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg5OB9bTgyrl2y5gxJS2YB3_32U9VtOT3X314S60XYb9s7bnbQGl-sRwBVJE7mXeBV4WUzBG6NRxZP1KmONU0pxUSTNxXDPS57JAUY2ZW0HgM12zO-Y0fc8cXhx-yMyqDc7NhYChTkzKxNIJHIMW3BFDV8T-_Y_-iS05nF_WbDGEiDjgpix8tIe7ahE8SQ/w225-h400/ADS-B-Receiver.jpg" width="225" /></a></div><br />I therefore made a simple design in <a href="https://www.kicad.org/"><i>KiCAD</i></a> and submitted it to three PCB manufacturers (<i>Eurocircuits, Ourpcb, Pcbonline</i>), to see which board stock is the most cost effective. This showed me a number of things:<p></p><ul style="text-align: left;"><li>The board makers do not necessarily have the advertised stock, or</li><li>they may not be set up to actually use it, and</li><li>the prices vary dramatically, as I expected.</li></ul><p>The most expensive board turned out to be <i>Rogers 4003C</i>, mainly because the manufacturers want to charge me hundreds of Euros to set up their machines to use it. Here is a little relative cost table with the <i>RO4003C</i> cost as 1:</p><ul style="text-align: left;"><li>RO4003C = 1</li><li>RO4350B = 0.44</li><li>I-Tera MT40 = 0.32</li><li>IS400 = 0.36</li><li>FR4 generic = 0.18</li></ul><p><i>RF boards therefore cost two to four times more than garden variety boards, although the difference becomes smaller in larger quantities and when you order a hundred, it may not matter too much what you make it from.</i><br /></p><p>The prototype patch antenna was made from <i>Rogers 4350B</i>, which has the following RF parameters:</p><ul style="text-align: left;"><li>Permittivity <i>Dk</i> = 3.66</li><li>Loss <i>Df</i> = 0.0031 </li><li>Dielectric width <i>Dw</i> = 0.508 mm</li><li>Cu 1 Oz = 36 um <br /></li></ul><p>Garden variety <i>FR4</i> board has a loss factor of <i>0.016</i> vs<i> 0.0031</i> of the <i>RO4350B</i> board. <i>This makes a big difference, since you want the antenna to radiate, not heat up like a dummy load. For the amount of time and effort required to design it, one can just as well use the best possible board and get the best possible antenna.<br /></i></p><h3 style="text-align: left;">Conformal Aircraft Skin Mounting <br /></h3><p>This PCB antenna is superior (military) quality and optimized, suitable for use on an aircraft as a transmit antenna. <br /></p><p><i>The patch is slightly flexible, so it could be mounted conformally with the aircraft skin and the weight is only 23 gram, so the antenna will weigh less than the RF coaxial cable. The antenna is circular polarized, so that one can mount it almost anywhere on an aircraft fuselage: top, bottom, wing or tail fin; or use it horizontally on the ground and get a good signal all around.</i></p><p>The best way to mount the antenna to an aircraft fuselage, is on the inside of a RF window, made from fibre glass reinforced epoxy. <i>(Look for an existing small access hatch and redesign the hatch from fibreglass with the antenna bolted on the inside!).</i> If the antenna is in contact with the glass, it will be detuned by about 500 kHz, which is not significant, so you do not need tall spacers. The board can be bent a bit in one direction - it will not affect the pattern significantly.</p><p><i>This way, you get an invisible antenna with no drag.<br /></i></p><h3 style="text-align: left;">Tuning and Testing<br /></h3><p>I measured the prototype board and it was off by a mile and a half - as I expected - with RF, theory and reality never meet in public. So I trimmed it <i>Ye Olde Fashioned Way </i>with calipers, a steel ruler and scalpel, until it was spot on.</p><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh50IqFZ0Qe2ZoTTkXH61LHvHAhUlD5te5XyZxK0Vrv6GRZzOlPE9c5MzOYaGqubXi_YcOBp05yayi0t5aBvEyY2_yrqee4SaQPPkOeVTdvI4Ql4U8S3G0iFFQht85d_-4mUtkHxhbxMY4mA2DvdGQNFt1KqKZ98ls4nihdQN7kAbj9ppqyXMCXr6G2wzs/s2075/ADSB-1090-VSWR.jpg" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1435" data-original-width="2075" height="221" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh50IqFZ0Qe2ZoTTkXH61LHvHAhUlD5te5XyZxK0Vrv6GRZzOlPE9c5MzOYaGqubXi_YcOBp05yayi0t5aBvEyY2_yrqee4SaQPPkOeVTdvI4Ql4U8S3G0iFFQht85d_-4mUtkHxhbxMY4mA2DvdGQNFt1KqKZ98ls4nihdQN7kAbj9ppqyXMCXr6G2wzs/s320/ADSB-1090-VSWR.jpg" width="320" /></a></div><p><i>The VSWR is now a perfect 1.0 at 1090 MHz, and the 3 dB (half power) bandwidth (VSWR = 6) is about 30 MHz.</i> A patch is very narrow band as you can see on the graph, so you may not need to use a bandpass filter with it - which could save you some money and complexity for an ADS-B receiving station. This is one of the reasons I opted for this design.<br /></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIPs5dz1gJLVfxvBjshoogHz4mUnykZcjx_i9BdsKvwXNUner1t-438pCKv-QxvWS8xQqwXT9XxVwW9lTSplmIPecyHQVqb5WZWfL51TkLVFWvaIfr9mDQoOHv899Rlue4n3OMI2VLrUbS11JslSMlnUYAHdkARqcqSYkZkIXDF6JY1b2scRWRo5bqYIg/s2107/ADSB-1090-Smith.jpg" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1399" data-original-width="2107" height="212" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIPs5dz1gJLVfxvBjshoogHz4mUnykZcjx_i9BdsKvwXNUner1t-438pCKv-QxvWS8xQqwXT9XxVwW9lTSplmIPecyHQVqb5WZWfL51TkLVFWvaIfr9mDQoOHv899Rlue4n3OMI2VLrUbS11JslSMlnUYAHdkARqcqSYkZkIXDF6JY1b2scRWRo5bqYIg/s320/ADSB-1090-Smith.jpg" width="320" /></a></div><p>The impedance is almost perfect at<i> 49.7 Ohm</i>.</p><p>The VSWR is not too important for a receive
antenna, but <i>a good VSWR does indicate that the antenna is probably as good
as it can be</i>. In practice I can see a small difference between this patch and one that is 6 MHz off: <i>Sitting in my office window, the good one picks up planes way past Brno (100 NM) and the sad one comes a few nautical miles short</i>.</p><p></p>Now I got to measure the tuned antenna with calipers and have another prototype made. In your neck of the woods you may want to use someone else, but <a href="https://www.eurocircuits.com/"><i>Eurocircuits</i></a> is convenient, since one can simply drop a <i>KiCAD pcb file</i> on their web page to get a quote, you don't need to make <i>Gerbers</i> - they will do the file conversions for their machines. <p></p><p><i>In one off quantities, a small patch antenna will set you back about 150 Euros - sadly, it is not a cheap hobby... </i></p><h3 style="text-align: left;">Question Time </h3><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhXBad0ClTuFj8bnaw_Bh7H-dN0PXKY_LJAhf1yvGvbEVrZTaCH_bCyYDIh_xMYtbx9AYXnHPBDGW15JK6qsjsLhHkG75xclCgS7Ppt4m5W5hAxsgBItfzp7wxW2S_PNpojcngTxMT0OlPjYrCONFBWoT277EhaCZxJCzKJ5KS2PA8_gSYsV4XREzhY-G4/s640/100NM.PNG" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="640" data-original-width="295" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhXBad0ClTuFj8bnaw_Bh7H-dN0PXKY_LJAhf1yvGvbEVrZTaCH_bCyYDIh_xMYtbx9AYXnHPBDGW15JK6qsjsLhHkG75xclCgS7Ppt4m5W5hAxsgBItfzp7wxW2S_PNpojcngTxMT0OlPjYrCONFBWoT277EhaCZxJCzKJ5KS2PA8_gSYsV4XREzhY-G4/w185-h400/100NM.PNG" width="185" /></a></div>A commenter asked: <i>How do you Tune a Patch Antenna??? </i><p></p><p>Hmm...</p><p>The easiest antenna to tune is a telescopic, but when you bump it, it can go out of tune, so I use a permanent marker to draw rings around the joints. One can wipe it off again with alcohol solvent.<br /></p><p>A holy antenna made from strips of rigid strapping bolted together, can also be tuned easily by moving the pieces one hole this way or that.<br /></p><p>Patch antenna tuning requires some sharp craft tools: <i>A big mug of coffee, steel ruler, scalpel and calipers, pencil and eraser (or sharpie and alcohol), plus a most secret material called Copper EMI Tape.</i></p><p><i>No matter how careful you are, a hand carved antenna will be off by half a mm, one way or the other and would therefore have to be tuned.</i> </p><p>In general almost anything you do to a patch antenna will lower the centre frequency (Fc), but here are some tips:</p><ul><li>Drilling a small hole anywhere, will lower the Fc by about 500 kHz.</li><li>Coating the antenna with conformal varnish will lower the Fc by about 500 kHz. <i><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSsR990rU2AN0ezb3bBz5iUr8JhpjcDfRl_fq5hwX1Rq_x5emrv51_r_KoVkG1mzLIROGBOXkSBo0fWmf40mWYt5LSel3u8VfnDIAjZuhvgSboLDhU6LApBSV9IOg3_VAZcp6EM5stvchcar5ZTCyaXu33Z2E51pXKnqacXX7h7OA7QCmTxTGtBvsZH2Q/s2016/toolz.jpg" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1322" data-original-width="2016" height="210" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSsR990rU2AN0ezb3bBz5iUr8JhpjcDfRl_fq5hwX1Rq_x5emrv51_r_KoVkG1mzLIROGBOXkSBo0fWmf40mWYt5LSel3u8VfnDIAjZuhvgSboLDhU6LApBSV9IOg3_VAZcp6EM5stvchcar5ZTCyaXu33Z2E51pXKnqacXX7h7OA7QCmTxTGtBvsZH2Q/s320/toolz.jpg" width="320" /></a></i></li><li>Cutting a 50 Ohm stripline feed into it, will raise the Fc by a several MHz.</li><li>Cutting slots into the sides will increase the bandwidth a little and lower the Fc by several MHz, depending on how deep you cut, about 2 to 3 MHz per mm. </li><li>Trimming 1 mm off the two sides will raise the Fc by 5 to 10%.</li><li>Cutting off two 20 mm triangles on opposing corners for circular polarization, will increase the Fc by about 60 MHz.</li></ul><p>OK, so you cut off too much - <i>that always happens</i>:</p><ul><li>You could resort to cutting the corners to move the Fc far up, or you can add a little bit of metal by sticking some EMI tape onto the antenna, but the effect is not exactly the same as not having cut off too much to begin with... </li></ul><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiOqFJw5UpLrW5dtA7r53fJkt-kiiCQYfUy7blZ0i62VWa5uy7Ho5oBB7QM-XFA0RHhGxlZp_BGtfOa77ZW1ApsRfwtmtOjLZMiAYizOIUFonHhZFEmXqZmiOF1wS_wFGzudlanJyWDDkvNrJ2KkkxP5jQMU0Bq0srl1OB9_3Ak0vAnCzqxwmiqRp1yG6E/s1458/Hand-Carved-ADSB.jpg" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1193" data-original-width="1458" height="262" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiOqFJw5UpLrW5dtA7r53fJkt-kiiCQYfUy7blZ0i62VWa5uy7Ho5oBB7QM-XFA0RHhGxlZp_BGtfOa77ZW1ApsRfwtmtOjLZMiAYizOIUFonHhZFEmXqZmiOF1wS_wFGzudlanJyWDDkvNrJ2KkkxP5jQMU0Bq0srl1OB9_3Ak0vAnCzqxwmiqRp1yG6E/s320/Hand-Carved-ADSB.jpg" width="320" /></a></div><p></p><p>When is it good enough?</p><p><i>A Voltage Standing Wave Ratio (VSWR) below 2 means that less than 10% of the power is reflected in a transmit antenna and that is usually good enough. A VSWR of 6, is 50% reflected power and that is the 3 dB bandwidth level. </i></p><p>Remember however that <i>a dummy load has a perfect match and transmits or receives nothing</i>, so VSWR is not necessarily an indication of the antenna efficiency - <i>you have to use low loss (expensive) PCB</i>.</p><p>A practical lab bench radiation efficiency test, is to <i>wave your hand in front of the antenn</i>a (15 cm or so) while watching the VSWR on a VNA. That will quickly give you an indication of the antenna radiation pattern.<br /></p><p><i>As a dedicated home brewer, you can make a patch with a couple of small pieces of copper that you can slide over the slots with a toothpick and sweat solder with a hot soldering iron to tune it spot on.<br /></i></p><p>The standard trick for a manufacturable antenna is to get some sample stock from a PCB manufacturer, design the prototype patch antenna for a frequency 5 to 10% above the desired Fc, then get busy with the ruler and scalpel at the <strike>workshop</strike>kitchen table, to make the antenna the hard way using your mad craft skillz and trim it with side slots until it is on target. Then finally, you can measure it with calipers, set the KiCAD grid and line width to 100th of a mm, draw the footprint and have a board made. If you are very lucky, then that very first manufactured board will be good enough, without further tuning required.</p><h3 style="text-align: left;">Purchase Orders <br /></h3><p>If you are interested in buying this antenna, you could send me a message and once there are multiple takers, I'll have a batch made at <i>Eurocircuits</i>, next door in Hungary.</p><p>La voila!</p><p>Herman</p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjyO8QQblEBPpgIoyyPjzyj9x74jRGpxFa7InU37j1VSeSLHe8O83l8BPmGbllXxQOPF_VKchGJQvbixgXQ7ZSbEfjfh70XpgGrnxWj20W7LUpao3iKhz0fxZJStH6YgJxf2CYmAgElm7xxo7E5YMfNZfEu9F0aCxsdKLGHBwjAN8w0afo7ARmpXi7UMZI/s306/Screen%20Shot%202023-10-02%20at%2012.20.35%20PM.png" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="68" data-original-width="306" height="44" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjyO8QQblEBPpgIoyyPjzyj9x74jRGpxFa7InU37j1VSeSLHe8O83l8BPmGbllXxQOPF_VKchGJQvbixgXQ7ZSbEfjfh70XpgGrnxWj20W7LUpao3iKhz0fxZJStH6YgJxf2CYmAgElm7xxo7E5YMfNZfEu9F0aCxsdKLGHBwjAN8w0afo7ARmpXi7UMZI/w200-h44/Screen%20Shot%202023-10-02%20at%2012.20.35%20PM.png" width="200" /></a></div><br /> <p></p><p> </p><p>Also see:</p><ul style="text-align: left;"><li><a href="https://www.aeronetworks.ca/2018/07/patch-antenna-design-with-nec2.html?sc=1695131363233#c4044767088964058859">https://www.aeronetworks.ca/2018/07/patch-antenna-design-with-nec2.html?sc=1695131363233#c4044767088964058859</a></li><li><a href="https://www.aeronetworks.ca/2023/10/earth-observation-satellite-1700-mhz.html">https://www.aeronetworks.ca/2023/10/earth-observation-satellite-1700-mhz.html </a></li><li><a href="https://www.aeronetworks.ca/2019/03/driving-quad-patch-array-antenna.html">https://www.aeronetworks.ca/2019/03/driving-quad-patch-array-antenna.html</a></li></ul><p><br /></p><p><br /></p><p><br /></p>Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com0tag:blogger.com,1999:blog-1589959253862674712.post-23015860324191575362023-01-26T00:31:00.011+01:002023-10-04T10:31:29.973+02:00ADS-B Quarter Wave Whip Antenna<p>I reclined in the winter garten nursing my back and watched a gaggle of geese and aircraft soar overhead, which made me realize that it's been a while since I made an Air Traffic Control (ATC) antenna, so I dug in my <i>Junque Bochs</i> for an old <i>Raspberry Pi v3, a RTL-SDR dongle and a tripod telescopic test antenna</i>, downloaded the latest ADS-B (<span>Automatic Dependent Surveillance-Broadcast</span>) decoder image from <i><a href="https://www.adsbexchange.com/">https://www.adsbexchange.com/</a> </i>and went to <strike>work</strike>play.</p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjVsMd9VqgzpxfRnEPw4iWWHoyPeTomzWTlsXO5Yq4f01TSglbRF3fW01zPMdWJ_tpnWTMNVdzxJCeLw18D20Tn71KvatSec-CX_Y1-qvthuseQBhIiaRmLi3w1vEBLOUtGBr6ejW-JIxudTi6h9Bdut0ACFHY_RWENRBj_q3sH5hLZAUIyxN6IcIqo/s1280/adsb-map.jpg" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1280" data-original-width="751" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjVsMd9VqgzpxfRnEPw4iWWHoyPeTomzWTlsXO5Yq4f01TSglbRF3fW01zPMdWJ_tpnWTMNVdzxJCeLw18D20Tn71KvatSec-CX_Y1-qvthuseQBhIiaRmLi3w1vEBLOUtGBr6ejW-JIxudTi6h9Bdut0ACFHY_RWENRBj_q3sH5hLZAUIyxN6IcIqo/s320/adsb-map.jpg" width="188" /></a></div><p></p><p>The last time I worked with ADS-B transponders was maybe five years ago, when I used a RTL-SDR to test a Sagetech Mode-S ATC transponder and the free decoder software has improved dramatically since then. It took about an hour to set the system up and I could immediately see a handful of aircraft, as far away as 80 nautical miles (150 km), using a wonky little telescopic antenna on my office window sill.<br /></p><p>After a while I captured an <i>Emirates A380, a USAF Galaxy and a Slovak AF LET 410 Turbojet</i> from the military airport nearby and I could see aircraft all the way to Vienna and Brno on my phone web browser - so how about aircraft around Prague?</p><p><i>To make a (hopefully!) better antenna, I broke out the O'l Slide Rule and calculated a quarter wavelength of 1090 MHz using <span> λ</span> x f = c, and <span> λ = c / f, with c = 299792458 m/s. </span></i></p><p><span>Therefore an <i>ideal quarter wave whip needs to be 68.8 mm long</i>, or that is what the <strike>comic</strike>text books would want you to believe. </span></p><p><span>In practice an antenna is always shorter than the ideal, due to coupling to the environment, and the antenna support system - <i>usually about 3% shorter.</i> </span></p><p><span></span></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhnZA6cB8QBPjanaDj3AvjgeuyG_zR07C55iwBr9JWmUSv9FgUALJB3pt0nNRqO2hOs2CduGCttxlgNpQ43hHmRUzrFCz1Sf1D0lQPgMoOtoHVnUm1CBqLpNEI93fbLpBo_2flndeydtqNXT2ADtRXG5rmbkl1b-XRMJFoDXbgpweKIuFpxXfn7BEvw/s1512/adsb-quarterwave.jpg" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1512" data-original-width="1484" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhnZA6cB8QBPjanaDj3AvjgeuyG_zR07C55iwBr9JWmUSv9FgUALJB3pt0nNRqO2hOs2CduGCttxlgNpQ43hHmRUzrFCz1Sf1D0lQPgMoOtoHVnUm1CBqLpNEI93fbLpBo_2flndeydtqNXT2ADtRXG5rmbkl1b-XRMJFoDXbgpweKIuFpxXfn7BEvw/s320/adsb-quarterwave.jpg" width="314" /></a></div><p></p><p><span>If you want your antenna to be spot on, you need a Vector Network Analyzer (VNA), so you can clip little pieces off the driven element, till the center frequency is exactly where you want it to be. If you don't have a VNA, then you need to build five or ten antennas, each 1 mm shorter than the previous and then try them all and see which one works best, but <i>to measure is to know!</i><br /></span></p><p><i>With the help of my trusty Chinese VNA, I eventually found that the element length should be 62.5 mm, which is a good 10% shorter than the calculated ideal!</i></p><p>To make the antenna base, I cut a little wheel of fibreglass PCB with a hole saw and mounted it on a tripod with a piece of rigid strapping (a holy metal strip usually used to tie roof rafters together, but which is great for making ad hoc brackets, since it has an endless number of mounting holes at the ready).</p><p>The antenna elements were made from 18 SWG (1 mm) tinned copper wire (<i>or five unrolled paper clips!</i>), which is easy to work with. <br /></p><p>The whip is soldered to the tip of a RG316/U coax, with the shield soldered to the copper board and the tip pointing up through the middle of the hole. I glued it in place with epoxy. </p><p>To make an earth plane, I soldered four quarter wave wires to the base PCB and bent them down - <i>if you keep the earth plane flat, then the antenna will be very narrow band and difficult to tune</i>. </p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEig7oWMBsX18gzI9cJgpxCxpuG76fGY0TiL9xJ_Cxw7ClReosSYY6gBX0an4dUYxpWcxUwLTd-1W7NWMs0tyYKa_qrQMgxrGYUSMTO9gqfqXWtdYdayQahq27KTDHb8LsYrZxYi21vWpGKoAVSj-Lw4dd6zdOn2TqeJcbBBmjWJ4FoEyXOfHWDsLe6r/s2016/adsb-smith.jpg" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1512" data-original-width="2016" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEig7oWMBsX18gzI9cJgpxCxpuG76fGY0TiL9xJ_Cxw7ClReosSYY6gBX0an4dUYxpWcxUwLTd-1W7NWMs0tyYKa_qrQMgxrGYUSMTO9gqfqXWtdYdayQahq27KTDHb8LsYrZxYi21vWpGKoAVSj-Lw4dd6zdOn2TqeJcbBBmjWJ4FoEyXOfHWDsLe6r/s320/adsb-smith.jpg" width="320" /></a></div><p></p><p>Bending the wires down, makes the earth plane fade away towards the horizon, which makes the antenna much more calm and open minded. This bandwidth widening effect is amazing to see on a VNA - about 45 degrees seem to be optimal. I also added a couple of ferrite beads to the wire, but found that they don't have any effect - the bent earth plane wires dominate.</p><p>To tune the antenna, I let the VNA run and <i>snipped tiny 1 mm pieces off the tip of the whip, until the VSWR dip was near enough to 1090 MHz</i>. To tune an antenna, only adjust the driven element, leave the other metal parts alone.<br /></p><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9firvvQuSS4RxTqqY_1Ro3SWXC1pR91uSidqdCmxKj9SsKFWbaYdOST1ObU-to9gVcN6Iv4DSn41yESzKOL_6rElnbig7ZZam5Q98UGQ17aE6s_yXuzGn4TIfySA3YgHDWmCrV2o1LDaE5w5if8njp9i5JMlZtQa1m8Cv6ehypkcMhTnrdhdcGE8V/s2016/adsb-vswr.jpg" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1512" data-original-width="2016" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9firvvQuSS4RxTqqY_1Ro3SWXC1pR91uSidqdCmxKj9SsKFWbaYdOST1ObU-to9gVcN6Iv4DSn41yESzKOL_6rElnbig7ZZam5Q98UGQ17aE6s_yXuzGn4TIfySA3YgHDWmCrV2o1LDaE5w5if8njp9i5JMlZtQa1m8Cv6ehypkcMhTnrdhdcGE8V/s320/adsb-vswr.jpg" width="320" /></a></div><p><i>The final tuned up antenna presented a VSWR of 1.1 and an impedance of 48 Ohm at 1090 MHz, which is a pretty good match to a 50 Ohm coaxial cable.</i></p><p>With the new finely tuned antenna sitting on my window sill, <i>I can see about twice as many aircraft, up to about 108 nautical miles (200 km) away.</i></p><p>If you can mount an antenna outdoors, then it will work much better, but that is too much effort for me. I'll just leave it in the window. <br /></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg2sfgLsEJW-SWpf6SEDUl1pG839w6lPQOJj1eNOKWWkhi34aUDFB9_uF3DK4dOLXQ362SH1rqfxBWOXEuPHSZ3vHUaQBWyIx7OI6K8Nl1m_z6Vn939sI8Q6R79b8Odq-7jZw4JEFl0rkht-IRYgqKNamsMYqXuI7m_hEFByAFEEAUlnkibWMsN0jyX/s1280/adsb-200km.jpg" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1280" data-original-width="750" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg2sfgLsEJW-SWpf6SEDUl1pG839w6lPQOJj1eNOKWWkhi34aUDFB9_uF3DK4dOLXQ362SH1rqfxBWOXEuPHSZ3vHUaQBWyIx7OI6K8Nl1m_z6Vn939sI8Q6R79b8Odq-7jZw4JEFl0rkht-IRYgqKNamsMYqXuI7m_hEFByAFEEAUlnkibWMsN0jyX/s320/adsb-200km.jpg" width="188" /></a></div><p><br />I think this antenna build should be quite repeatable - the downward bent reflector wires make the bandwidth wide enough that it should work very well, even if your build is off by 50 MHz this way or that.</p><p>If you would add a 15dB Low Noise Amplifier to it, then you will get signals from 400 km or more, with too many aircraft to see on a phone. A little googling will find little ready built pre-amplifiers specially made for ADS-B, with an integral SAW filter to reduce interference, but I don't think I'm going to bother, since my tuned-up antenna is good enough.<br /></p><p></p><p><i>It would be best to build an antenna on top of a bulkhead mounted RF connector</i>, but I buy RF jumper cables from Pasternack or Mouser for serious work and then when one end breaks off, I use the remainder for these kind of experiments, which usually reduces the cost of my hobby antennas to practically zero.<i></i></p><p><i>For the adventurous, here is an ADS-B patch antenna:</i></p><p><a href="https://www.aeronetworks.ca/2023/09/rf-controlled-impedance-pcb.html"><i>https://www.aeronetworks.ca/2023/09/rf-controlled-impedance-pcb.html<br /></i></a></p><p>La Voila!</p><p>Herman<br /></p>Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com0tag:blogger.com,1999:blog-1589959253862674712.post-15392579807197691202023-01-04T21:52:00.012+01:002024-02-23T10:13:48.233+01:00To C or not to C, That is the Question<p>As most would know, the Kernighan and Ritchie C Programming Language is an improved version of B, which is a simplified version of BCPL, which is derived from ALGOL, which is the Ur computer language that started the whole madness, when Adam needed an operating system for his Abacus, to count Eve's apples in the garden of Eden in Iraq. The result is that <i>C is my favourite, most hated computer language</i>, which I use for everything.</p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh1aH6yd0VWJjy9mkwVBPCnLeIdznd4zWELcPcAmlKYOfz1yruwDHbUMFN4cHLCwrTZ5jzY8W_mZ9AaxcOmpQLEFMo20weNcmebgxKk3b4oKoZlnXqRxuisc5jynOKOC3W4CTRFM70z5mrq1xbjh_-1AkgHucKDsAGM-9WBGs9-Pu64mTBEWnZd4F-7/s474/univac-operator.jpg" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="445" data-original-width="474" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh1aH6yd0VWJjy9mkwVBPCnLeIdznd4zWELcPcAmlKYOfz1yruwDHbUMFN4cHLCwrTZ5jzY8W_mZ9AaxcOmpQLEFMo20weNcmebgxKk3b4oKoZlnXqRxuisc5jynOKOC3W4CTRFM70z5mrq1xbjh_-1AkgHucKDsAGM-9WBGs9-Pu64mTBEWnZd4F-7/s320/univac-operator.jpg" width="320" /></a></div><p></p><p>At university, I learned FORTRAN with punch cards on a Sperry-Univac, in
order to run SPICE, to simulate an operational amplifier. <i> Computers rapidly lost their glamour after that era!</i><br /></p><p>Nobody taught me C. I bought the book and figured it out myself.</p><p>Over time, I wrote a couple of assemblers, a linker-locator, various low level debuggers and schedulers and I even fixed a bug in a C compiler - not because I wanted to, but because I had to, to get the job done! </p><p>Much of my software work was down in the weeds with DSP and radio modems (<i>Synchronization, Compression, Encryption, Error Correction...</i>) - which, nobody taught me, I had to figure it out myself. Those were indeed primitive times.<br /></p><p><i>This article is however about the other C - Cancer</i>. <i>About 30% of people get some kind of cancer. It is distressingly common.</i><br /></p><p>Similar to learning C, Cancer is a journey of discovery, it is not something engineers would study at university - maybe we should though, since <i>there is a huge market for diagnostic and treatment machinery</i>.<br /></p><h3 style="text-align: left;">High School Biology Revisited<br /></h3><p>As you should recall from your high school biology, almost every cell in a mammalian body has one or more mitochondria. Muscle and brain cells can have several. These organelles resemble bacteria, since they have a cell membrane. The purpose of the mitochondria is to manufacture special molecules that are needed by a cell. The most common product is ATP (Adenosine Triphosphate). ATP is the main source of fuel for a cell, since it can be readily oxidized to produce heat.</p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQeGh0rb7_sWwUcejN3GkLsJ8obStxsYiNwmTXD46xki1G3a_25tNcb0rBtEyR9PaKqvvsRvlUnADc-vT69QhC1YUBHV3B1y3aDoKOKYB0mBObze13pG2cQxMIr7xlgxE6tFgZzUdxcwa4ZUB882ADlMwKRth6BP0M01Nyk2Wswfsq3YPBnDLuSHjM/s357/mitochondria.jpg" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="137" data-original-width="357" height="123" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQeGh0rb7_sWwUcejN3GkLsJ8obStxsYiNwmTXD46xki1G3a_25tNcb0rBtEyR9PaKqvvsRvlUnADc-vT69QhC1YUBHV3B1y3aDoKOKYB0mBObze13pG2cQxMIr7xlgxE6tFgZzUdxcwa4ZUB882ADlMwKRth6BP0M01Nyk2Wswfsq3YPBnDLuSHjM/s320/mitochondria.jpg" width="320" /></a></div><p></p><p>Cancer is primarily a mitochondrial disease. The mitochondria in a group of cells sometimes go haywire and start to produce the wrong chemicals and too little ATP. The unwanted chemicals are a strain on the liver and kidneys, which must get rid of it and the lack of ATP can make one feel super tired very quickly. <i>A cancer patient should drink lots of water, to help the liver and kidneys.</i><br /></p><p>The mitochondria normally also produce chemicals that trigger cell death - apoptosis. If they stop producing that, the cells do not die when they should and the result could be growth of a hard tumour of faulty cells, which consume nutrients and produce poisons. <i>A tiny tumour a few mm in diameter is enough of a producer-consumer problem to make one feel really dreadful.</i></p><p>Diseased mitochondria can mean that while walking on level ground may be OK, climbing a single flight of stairs can feel like climbing a mountain, making one reach for the banister and leaving one wobbly and out of breath at the top.<br /></p><p>One may be able to do something for an hour, but then have to lie down for ten minutes to recover. <i>If this is you - better go see a doctor and keep going till you find one that actually listens to you.</i><br /></p><h3 style="text-align: left;">Snake Oil and Blood Letting<br /></h3><p>Engineers have no issue with telling a client: <i>I don't know, but I will find out and get back to you next week.</i></p><p>Some Doctors however, since the use of snake oil and blood letting in time immemorial, will never admit that they don't know. Some will spin a feel good story, give an Aspirin and tell one to come back in 10 days. <i>The better doctors, will do blood tests.</i></p><p>When I hurt my back while working around the house and eventually went to a doctor, complaining about a stiff back and terribly tired legs, he checked and said that my spine is OK, the muscles can be sorted with a massage session, but my tired legs require a battery of blood tests and when he looked at the blood tests, he referred me to a different doctor.</p><p>The second doctor went: <i>"Hmm, I can see why you were sent to me"</i> and immediately ordered a full body MRI scan.</p><h3 style="text-align: left;">Magnetic Resonance Imaging</h3><p>I happened to work at <i>Elbit in Israel </i>on a military project, when they <i>developed the first MRI machine</i>. Everyone in the company were absolutely astonished when the first pictures started to appear. The anatomical detail was just mind blowing compared to the familiar fuzzy X-ray pictures.<br /></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEic_PKG3RiCdlJam0_rmS_iMccrI1PCbU7GUovZ0oB_x2JRWozfVpPSBITMbOy3umYZA50zyvdHrN8wkuMj7Ml4zR6i83PrY8uQpz4QBqzAlxiZGnDIm31GMPBCbGSvOgfbuiJDMwhBMb8mkXIo0VdO2_u28x9GufJpX4HoUWpjdpHKTCE142oeNPS9/s474/elbit-mri.jpg" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="316" data-original-width="474" height="213" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEic_PKG3RiCdlJam0_rmS_iMccrI1PCbU7GUovZ0oB_x2JRWozfVpPSBITMbOy3umYZA50zyvdHrN8wkuMj7Ml4zR6i83PrY8uQpz4QBqzAlxiZGnDIm31GMPBCbGSvOgfbuiJDMwhBMb8mkXIo0VdO2_u28x9GufJpX4HoUWpjdpHKTCE142oeNPS9/s320/elbit-mri.jpg" width="320" /></a></div><p></p><p>An X-ray camera or CT Scanner can visualize soft and hard tissues. <i>A MRI Scanner though, is the closest thing to a mythical Star Trek Tricorder, since it can visualize the difference between healthy and diseased tissue.</i><br /></p><p>Full body scanners are always located in the basement of a hospital building, since they are incredibly heavy. The shielding provided by the surrounding earth also helps to get a good SNR (signal to noise ratio) which improves the picture quality.</p><p>When you visit a full body scanner, comfortable clothing is advised - athletic tracksuit pants and a T-shirt are good - you have to lie motionless in the machine for about 20 minutes. Bring a sports bag to keep your documents and all your metal trinkets and metal zippered jackets that you got to take off. A MRI machine is quite noisy, but for once in a lifetime, it is OK.<br /></p><p>When the doctor got the MRI results, he double checked the identified problem area with a small sonar scanner (it is also astonishing how small and effective these hand held devices have become), mentioned that there is a small tumour (about 7 mm) which started maybe three years ago and which should be curable, then referred me to an oncologist.</p><h3 style="text-align: left;">Cyclotrons</h3><p>When I was at university, I gave a hand (literally - with a steel file!) with the manufacture of huge magnets for a powerful <i>100 GeV four sector cyclotron</i>. It was envisaged for use for cancer treatment. The machine was completed, but never much used, since it was overtaken by cyclotrons with <i>superconducting magnets, which were smaller and cheaper to operate by a factor of hundred!</i></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgHCM0g4lIdMgHnybTocjK6Ng3HuNiXSIrla5WCbU7Dqqj4TyqU68j0athOkhTToqPBsuDWUPafhvl3h_z93aUp-BGcKy1uzoJ7LC1xeF8uqEUGiIZSNpwP-qv6765wnXyQxu6C9frzSafEtO30zsraDGZ2plhhs_T4Ly4J3ZXf-CLZHreUi46EI-Ze/s1635/cyclotron.PNG" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="911" data-original-width="1635" height="178" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgHCM0g4lIdMgHnybTocjK6Ng3HuNiXSIrla5WCbU7Dqqj4TyqU68j0athOkhTToqPBsuDWUPafhvl3h_z93aUp-BGcKy1uzoJ7LC1xeF8uqEUGiIZSNpwP-qv6765wnXyQxu6C9frzSafEtO30zsraDGZ2plhhs_T4Ly4J3ZXf-CLZHreUi46EI-Ze/s320/cyclotron.PNG" width="320" /></a></div><p></p><p>The old cyclotron was a beast, and was my first involvement with a working, but effectively failed project. The sad life story of many an engineer!<br /></p><p>Modern 10 GeV cyclotrons made by IBA in Belgium, are used to produce <i>radio active isotopes such as Iodine 124 or 18 FDG,</i> which previously required a nuclear reactor to produce. These isotopes are used in PET (Positron Emission Tomography) Scanners, which are used to look for cancerous tissue and heart problems.<br /></p><p>The cyclotron which I worked on still exists, simply because the machine is big, heavy and radioactive hot, so there is no economical way to recycle it. These older type machines are so inefficient that a hospital really cannot afford the huge amount of electricity needed to run them. Overtaken by new developments, they got entombed in locked and disused hospital basements forever. <i> </i></p><p><i>Maybe in a few thousand years, archeologists will dig some old cyclotrons up and wonder what the religious significance of these strange multi-sector objects were and ponder their alignment with the stars. Hopefully they won't die from a mysterious disease soon after examining the machines.<br /></i></p><h3 style="text-align: left;">PET Scanners</h3><p>Whereas a MRI Scanner is perfectly safe, using only extremely high power magnets to excite your tissue, a Positron Emission Tomography (PET) Scanner is decidedly unsafe and should only be used by patients who already have a serious heart problem or cancer (<i>After all, what are the odds of getting another cancer?</i> Well, sometimes that happens, but it is <i>really</i> bad luck.).</p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhiNuszKJzmloL7VoUkwR6oqRlv2B4PZlQvqwfjrs3A4mdq-_8qHIA-ac1xpHSSUSL79zoop9ZCdSkWIDa0_Eqo9WX0w3MeotEGqPK53K0zIatXxKZ70Kwc2U3WV5SbHwgKK7NDhLhniJNMzgWBIGb6JnZRBaqFmlG__8XovFYD5DDfU37piDfXi2OG/s900/pet-ct-scanner.jpg" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="599" data-original-width="900" height="213" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhiNuszKJzmloL7VoUkwR6oqRlv2B4PZlQvqwfjrs3A4mdq-_8qHIA-ac1xpHSSUSL79zoop9ZCdSkWIDa0_Eqo9WX0w3MeotEGqPK53K0zIatXxKZ70Kwc2U3WV5SbHwgKK7NDhLhniJNMzgWBIGb6JnZRBaqFmlG__8XovFYD5DDfU37piDfXi2OG/s320/pet-ct-scanner.jpg" width="320" /></a></div><p></p><p>A PET scanner needs to be close to a cyclotron - usually in an adjacent building - so staff can quickly stumble across the road with a heavy lead lined container with the required tracer isotopes, before it decays away to nothing. </p><p>Getting to a PET scanner may require a bit of a walk, from the parking lot, up a hill to a basement scanner, since the equipment is best dug into a mountain side for safety and shielding and most lay people would not want to get too close to it, out of an abundance of caution, so you may need to pass though multiple lackadaisical security gates to reach the facility.</p><p>From the outside, a PET scanner doesn't look much different from any other kind of full-body scanner - a big and expensive doughnut, with a movable bed. <i>It is a positron sensor system that measures the concentration of radio-active tracer in your organs</i>. Areas with very high blood flow will show up hot and an experienced radiologist knows what should be glowing hot and what should not be.</p><p>Different types of cancerous tumours, brain and heart problems are best seen with different tracers. Brain scans use radio-active Glucose and most other things use Iodine. Therefore, patients are grouped in batches, so that the cyclotron can manufacture the required isotopes. Therefore you will find yourself with an amazing crowd of people with similar problems. <i>Over the next few years, you will meet the same bunch of crocked up old fogies multiple times, so you can just as well introduce yourself!</i></p><h3 style="text-align: left;">Glowing In The Dark <br /></h3><p>A PET scan requires some preparation. A nurse will put you in a cubicle and make you drink a litre of drilling fluid (Barium Sulphate) - it really tastes like drilling fluid too - and after a while you will get a drip with the Iodine or Glucose tracer. The drilling fluid absorbs background radiation and improves the picture contrast. After leaving the tracer to circulate for about 40 minutes, you will get the scan, which takes about 20 minutes.</p><p>Just for fun, you could build a Geiger Counter (<a href="https://mightyohm.com/blog/">https://mightyohm.com/blog/</a>) to check the radiation levels around you. These devices have been causing engineers and scientists to wonder about life, the universe and everything, for more than a century.<br /></p><p></p><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQgeFl9-j4_OK5yfqHYbSLPCcZXDRWzvGwDOTVs3wbBM9tq_YqzGuwkSECX-5ri4CmkMf3t57U6-esguBXSVgkrOHFnB1nh64YPjpqtEBSVHCd3Jf77DN_XInsq7mD0hFdK2eSIPbIu3TazhteKdtSNEjVzirrIuWsfyrXypOx8OqW0XV8mFbNInp-/s1774/geiger.jpg" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="950" data-original-width="1774" height="171" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQgeFl9-j4_OK5yfqHYbSLPCcZXDRWzvGwDOTVs3wbBM9tq_YqzGuwkSECX-5ri4CmkMf3t57U6-esguBXSVgkrOHFnB1nh64YPjpqtEBSVHCd3Jf77DN_XInsq7mD0hFdK2eSIPbIu3TazhteKdtSNEjVzirrIuWsfyrXypOx8OqW0XV8mFbNInp-/s320/geiger.jpg" width="320" /></a></div><p></p><p>The MightyOhm Beta and Gamma ray detector is easy to build and works a treat - <i>Click, click, clicketyclick - Uhm, maybe I should get ECC memory for all my computers...</i><br /></p><p><i>Iodine 124 has a half life of about 4 days</i>, so for the next week, you will be glowing in the dark (unfortunately not really - could have been fun!) and you should avoid pregnant women and children, out of an abundance of caution. <i>FluoroDeoxyGlucose (18 FDG), has a half life of about 2 hours</i>, so you will be fine when you get home already.</p><p>I heard of one case where a guy was pulled over by very cagey and worried traffic police, because he triggered the Geiger counter in their car!<br /></p><h3 style="text-align: left;">The Bumpy Road to Recovery</h3><p><i>Getting diagnosed correctly is half the problem.</i></p><p>Once you are an oncology patient, general practitioner doctors may not really want to see you anymore and will tell you to first get the cancer fixed, then you can come back for whatever still ails you. Even a dentist may be very hesitant to treat you and may at most offer to fill an obvious cavity. If you break a dental crown, the dentist may try to fix it with plastic and will try his best not to replace the crown. Even a Thermal Spa or Massage is off limits to oncology patients. </p><p>There are various reasons for your newfound Persona Non-Grata Status. <i>The metabolism of an oncology patient is different from ordinary mortals.</i> There is a concern that the increased blood and lymph circulation caused by thermal waters and massage, can cause cancer to spread (Though this is not proven, but how will one ever prove/disprove it). <i>Due to a diminished immune system, you can however get sick more easily</i> and should avoid crowds and other sick patients, while minor infections that used to heal in a few days, may now take weeks or months to cure with repeated doses of antibiotics. <i>So there is some method in the madness and whatever you do, don't get sick - you are already sick enough!<br /></i></p><h3 style="text-align: left;">Treatments and Cures<br /></h3><p><i>Many people (about 97%) get cured of cancer and go into complete remission. </i> Others are treated periodically for decades, which is just as good. It is the luck of the draw how it will progress.<br /></p><p>Treatment of cancer takes many forms and can continue for months or years. Hormone therapy is used to change your metabolism and slow the cancer growth down. Chemo Therapy is a treatment with special poisons to kill certain types of cells. Internal radiation therapy (Brachytherapy) is used with certain hard tumours and involves implantation of tiny pellets of radioisotopes to damage the tumour from the inside. External radio therapy could be done with beams of photons (X-rays), or protons, to damage the tumour from the outside. Immunotherapy can be used to assist your immune system to clear damaged cells. It all depends on your particular problem and the available treatment facilities, since new potions and magical machines are invented all the time.</p><p>I got a series of 20 X-ray treatments to burn the little tumour, using a combination MRI and Linear Accelerator machine. The MRI rotates around to make a 3D image used to position you exactly right, to the mm, on a 6 DOF gantry and then the LINAC rotates around to zap the tumour. It is not painful, but not exactly something I would recommend for a leisure activity. <i>After 10 sessions, I could convince myself that I may be starting to feel better and by the 15th session I was sure of it.</i> However, radiation is a blunt weapon and you end up with damage from both the tumour and the radiation, so recovery will take a while.<br /></p><p>You may need to remain close to your assigned oncology centre and your life may need to be arranged around your repeated scans and treatments for the next few years - you got to adapt and get used to your new reality!</p><h3 style="text-align: left;">Dosage</h3><p>A LINAC is a magnetron powered tube, that accelerates electrons over a distance of about 50 cm and slam them into a heavy metal target, which releases X-rays, with an energy of about 20 to 25 MeV, which is then focused into a beam with a collimator. Some LINACs are configurable to enable the use of the electron beam to treat skin tumours and the X-ray beam to treat internal tumours.<br /></p><p><i>Just to put it into perspective. If you consider a full chest X-ray as the worst thing ordinary people will get, then 20 radiation treatments with a Magnetron powered LINAC, is equivalent to about 2000 to 3000 full chest X-rays, focused onto a small spot!</i><br /></p><h3 style="text-align: left;">Cancer Myths and Cures<br /></h3><p>There are a few cancer myths doing the rounds. Here are some for your amusement.<br /></p><p>The Italian Dr Simoncini, proposed that some cancer is caused by a fungus and tried to use baking soda to treat it. It did not work, but it could possibly be beneficial to people who have a fungal infection and cancer at the same time though.<br /></p><p>The Mayo Clinic studied the use of high dose Vitamin C to treat cancer. It doesn't work, but it is beneficial to people who do not absorb vitamin C properly and have (sub-clinical) scurvy and cancer at the same time. Vitamin C will make them feel a lot better within a few days, by curing the scurvy, but they will still have cancer.</p><p><i>The Human Papilloma Virus (HPV) has been proven to cause Cervical, Mouth and Throat Cancer</i>. There is now a vaccine against HPV, so there is at least one type of cancer which has a cure (prevention actually). This indicates that some other cancers may also be caused by viruses and eventually there may be a series of anti-cancer vaccines.<br /></p><p>So if you are looking for a miracle cure - there isn't one - but <i>taking multivitamins is always a good idea.</i> <br /></p><h3 style="text-align: left;">PS</h3><p><i>A year later, I can again climb stairs, walk around the village and swim 300 meters - that is a wee bit less than the 3000 meters I used to swim, but I just need to use a smaller pool... :)</i><br /></p><p>La voila!</p><p>Herman<br /></p>Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com0tag:blogger.com,1999:blog-1589959253862674712.post-69397519412270389282022-12-08T14:02:00.013+01:002022-12-08T16:41:47.814+01:00Aye Eye Bed-Time Story Generator<h2 style="text-align: left;"></h2><p>Machine Learning is used for various hard practical problems, such as the safe control of autonomous cars that have to navigate a cluttered and dynamic environment, without bumping off cyclists and running over old people trying to cross a village road. </p><p>There are also other more entertaining uses for it, such as the creation of bed-time stories for your grand children. (<i>Yup, I'm that old. I started learning programming FORTRAN on a Univac with punch cards, eh. Now get of my pennisetum clandestinum...</i> :).<br /></p><p>Go to <a href="https://chat.openai.com/auth/login" target="_blank"><i><b>OpenAI</b></i> <b><i>ChatGPT</i></b></a> and make yourself a free account: <i><a href="https://chat.openai.com/auth/login">https://chat.openai.com/auth/login</a></i></p><h3 style="text-align: left;"><b>Let the fun begin:<span style="-moz-text-size-adjust: auto; -webkit-text-stroke-width: 0px; caret-color: rgb(0, 0, 0); color: black; display: inline; float: none; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; letter-spacing: normal; text-align: start; text-decoration: none; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;"> </span></b></h3><p><i>Write a short story for ten year olds. Scary government people created a video of a moon landing and will catch you if you deny it.</i> <br /></p><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"></div><div style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhjloujCrJicSI8p_u4uD-Q5qe09mwnNkXK3ggipq0EtiSdwBN1hvlj2dgVMgO-xhmE8WobRDAeBuCgTvw5sXlMoWSZ-whGtIdCYx55N-aPeolPEkYEo4uipir4vx6nwRGAOfF8SP9j0mqc8VgcoUhQJsX-giAnm32dAoApMaUTQt1pjqYneANuGcuk/s827/moonshot.jpg"><img alt="NASA Artemis Moon Shot" border="0" data-original-height="552" data-original-width="827" height="214" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhjloujCrJicSI8p_u4uD-Q5qe09mwnNkXK3ggipq0EtiSdwBN1hvlj2dgVMgO-xhmE8WobRDAeBuCgTvw5sXlMoWSZ-whGtIdCYx55N-aPeolPEkYEo4uipir4vx6nwRGAOfF8SP9j0mqc8VgcoUhQJsX-giAnm32dAoApMaUTQt1pjqYneANuGcuk/w320-h214/moonshot.jpg" title="NASA Artemis Moon Shot" width="320" /></a></div><p style="text-align: left;"><i>Give the protagonist two buddies with distinctly different personalities.</i> <br /></p><h3 style="text-align: left;">Result:</h3><p style="text-align: left;"><i>Once upon a time, there was a young boy named Jack who loved watching the stars at night. He dreamed of one day becoming an astronaut and exploring the moon.<br />One day, Jack's teacher showed the class a video of a moon landing. It showed a group of astronauts walking on the moon's surface and collecting rocks and samples.<br />But Jack had his doubts. He didn't believe that the moon landing was real. He tried to tell his classmates, but they all thought he was crazy.<br />Luckily, Jack had two friends who believed him. One was a shy and timid girl named Alice, who was always afraid to speak up. The other was a bold and brave boy named Max, who was always ready for adventure.<br />Together, they decided to investigate the moon landing and find out the truth. They went to the library and did some research, and they discovered that the video was actually a cleverly made fake and that the government had been lying to the public for years.<br />They also learned that many people who questioned the moon landing had disappeared without a trace. They knew they had to be careful, or the government might catch them too.<br />Jack, Alice, and Max came up with a plan to expose the truth to the world. They made their own video and posted it online, showing the evidence of the fake moon landing.<br />The government was furious, but they couldn't stop the truth from spreading. Soon, the whole world knew that the moon landing was a hoax.<br />Jack, Alice, and Max were heroes for standing up for the truth, even though it was scary. And they all lived happily ever after.</i><br /></p><p style="text-align: left;"><br />Given the distinct lack of effort required to specify the story line, the result is quite entertaining and if the rug rats are not sleeping yet, then you can generate another one in seconds!<br /></p><p style="text-align: left;"><br />La Voila!<br /><br />Herman</p>Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com1tag:blogger.com,1999:blog-1589959253862674712.post-61437476185519615662022-10-12T11:20:00.006+02:002022-12-08T16:39:53.643+01:00Let There Be Light<p>I made a ceiling light fixture for my workshop (<i>it is supposed to be my garage</i>) from scrap wood. Since LED lights do not get hot, one can do that without danger of burning the house down, but it would be a good idea to incorporate a 250 mA polyfuse in there for peace of mind.<br /></p><p> </p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhpEMKmXi3t_R7pOkrh7_CZkiWfhzQbmRBeb6NycLyT3Il0x7xT3X5I8EHt-2BgXR_rcK0JLsjb9ReHZxy9y2IG3YiBcG4YlP8ywBd3RYs4kgBpnqC69x-vnBxrrwrhKkqwLD1dBP13rQjIsrGwncUKzHAzcT8skP8Q5QcfGxy2SpuiAKSLkC6_ym0i/s1382/ceilinglamp.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1382" data-original-width="1226" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhpEMKmXi3t_R7pOkrh7_CZkiWfhzQbmRBeb6NycLyT3Il0x7xT3X5I8EHt-2BgXR_rcK0JLsjb9ReHZxy9y2IG3YiBcG4YlP8ywBd3RYs4kgBpnqC69x-vnBxrrwrhKkqwLD1dBP13rQjIsrGwncUKzHAzcT8skP8Q5QcfGxy2SpuiAKSLkC6_ym0i/s320/ceilinglamp.jpg" width="284" /></a></div><p></p><p></p><p style="text-align: center;"><b>The light of my life.</b></p><p>To hide the ceiling house wires and chocolate block connector, I made a big hole in one block with a hole saw and glued it to another block. The vertical stick is mortised into the ceiling block - rubbed some wax on it all and there we have a little Tinkertoy Chandelier. I used bees wax, but good old boot polish will work as well and it comes in multiple shades.<br /></p><p style="text-align: left;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhKj9y9y4XaraKvw9mPE7zNSgKbs6pj8xasmf2I3-uaSVJUSEB5M4SuBy72z_3hxMUiIlxZdcXbgBl4giHtaEasT5H5arJGLbwIGraaMFGIQViZ6oAuqCu_pUmRlcvB-GuB8rN8BpIaVdVBZAePGiaE2sg3mqGL6sxv6i6JA3RVQqXsQMLpR-li5glQ/s3641/desklamp.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2802" data-original-width="3641" height="246" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhKj9y9y4XaraKvw9mPE7zNSgKbs6pj8xasmf2I3-uaSVJUSEB5M4SuBy72z_3hxMUiIlxZdcXbgBl4giHtaEasT5H5arJGLbwIGraaMFGIQViZ6oAuqCu_pUmRlcvB-GuB8rN8BpIaVdVBZAePGiaE2sg3mqGL6sxv6i6JA3RVQqXsQMLpR-li5glQ/s320/desklamp.jpg" width="320" /></a></div><p></p><p style="text-align: center;"><b>Cantilever Desk Lamp</b><br /></p><p><i>BTW, the easy/lazy way to make a rectangular mortise hole, is with a drill and a jigsaw. You just slowly grind the wood away with the saw blade till you have a perfect fit. A hammer and chisel does not work well on soft wood, no matter how sharp the chisel, while a jigsaw will happily chew up anything!</i><br /></p><p>I made two of the ceiling lights and one desk lamp. The lamp fixture is invisibly fastened to the end of the stick with a little screw and epoxy glue. The counterweight more or less balances it, which makes it easier to adjust and stay in place.<br /></p><p><i>Now I had enough of sandpaper and lamps for a while - if I can just stop sneezing!</i><br /></p><p>La voila!</p><p>Herman<br /></p>Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com0tag:blogger.com,1999:blog-1589959253862674712.post-54759116495417388022022-05-11T17:41:00.012+02:002023-07-13T11:46:19.098+02:00Wooden Post Thumper<p>We planted a new tree and wanted to stabilize it with three posts, so it won't blow over in a storm, while it is still young. It turned out that planting the tree was the easy part. Hammering the 2.5 meter support posts into the ground, was a whole 'nuther problem.</p><p></p><div class="separator" style="clear: both; text-align: left;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgqI-WgglpdHnJM6BIn7ryb8U1s06aRVp8qtKHcwP4dCY8OwmUAGbrVm-6IIjpNUA78rl9uGE-Ui6mn1ykoXkIqwZr0LdWlmjSeGeBoxBM6W6ELfmGiY0mjeP93p7YuTZ6m27CCREScSnZPstD_bsBIGJEBA6GGgAKzfc__MGocOMtIjMRaruRnLlAu/s2016/IMG_8399.jpg" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="2016" data-original-width="1512" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgqI-WgglpdHnJM6BIn7ryb8U1s06aRVp8qtKHcwP4dCY8OwmUAGbrVm-6IIjpNUA78rl9uGE-Ui6mn1ykoXkIqwZr0LdWlmjSeGeBoxBM6W6ELfmGiY0mjeP93p7YuTZ6m27CCREScSnZPstD_bsBIGJEBA6GGgAKzfc__MGocOMtIjMRaruRnLlAu/s320/IMG_8399.jpg" width="240" /></a></div><p></p><p>One cannot use a sledge hammer on a tall post, since climbing onto a ladder and swinging a heavy weight around, two meters above
ground, is sure to cause a rapid, unplanned descent from the ladder. </p><p><i>The safe solution is a pile driver - a heavy pipe that is closed at one end.</i><br /></p><p>I could not find a pile driver at the local hardware store and in any case it would cost around 65 Euro, so I took some scrap wood and a two hundred year old sledge hammer and there we go. The only expense was a handful of screws. </p><p>The thumper works remarkably well. It took longer to make the thumper than to set the three posts, but now I can also use it to drive in a sand point shallow well for the garden.</p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjiQh5Bwv-TKH0Rl9X_N3bcLtJGzINyW27od3MUzeFMjpFRY5vsPPU0jKyhI_5ZK7f0U5xcRKoIR21SUj9A5YT3M0KJuGG8Kq6pFJCgpfHz3Py-hSP2qc0ZDFOEliYPP1erLCdcDmIdu_AvPneZzqBDG0dBfpvNyt26h6WoloVHlh487-y_xZ_wwsu4/s2016/IMG_8401.jpg" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="2016" data-original-width="1512" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjiQh5Bwv-TKH0Rl9X_N3bcLtJGzINyW27od3MUzeFMjpFRY5vsPPU0jKyhI_5ZK7f0U5xcRKoIR21SUj9A5YT3M0KJuGG8Kq6pFJCgpfHz3Py-hSP2qc0ZDFOEliYPP1erLCdcDmIdu_AvPneZzqBDG0dBfpvNyt26h6WoloVHlh487-y_xZ_wwsu4/s320/IMG_8401.jpg" width="240" /></a></div><br /> <p></p><p>Start with a 15 cm piece of a square fence post - larger than the diameter of the stake that you want to drive in. Build a box around it such that you have a channel of at least 50 cm below the block. Strap a heavy weight above the block and there you are. It doesn't have to be ridiculously heavy.</p><p>Obviously a steel thumper will last forever, while a wooden one will eventually wear out/split, but a wooden one like this, will last long enough for use by ordinary mortals. <br /></p><p>Do sand the wood down to avoid getting splinters in your hands while using it.</p><p><br /></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjEl_2aZB1esVrAEveY8nnifykqnswGB7GzJBAL0ewf99cX_frT3tw3Syllae7GJmCFCMKbtuX3LJjpcd3lSjooFC8v4g5aCXi8J9EY0IWnvuKC2RT21vGdKb9Ojwk83qf9_4EYne40HcZju2wCCGn4QExzSXWVJSfrcB658yrFniIPc6S7aBrtnCjR/s2016/IMG_8402.jpg" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="2016" data-original-width="1512" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjEl_2aZB1esVrAEveY8nnifykqnswGB7GzJBAL0ewf99cX_frT3tw3Syllae7GJmCFCMKbtuX3LJjpcd3lSjooFC8v4g5aCXi8J9EY0IWnvuKC2RT21vGdKb9Ojwk83qf9_4EYne40HcZju2wCCGn4QExzSXWVJSfrcB658yrFniIPc6S7aBrtnCjR/s320/IMG_8402.jpg" width="240" /></a></div><p></p><p>Make a mark 50 to 75 cm from the tip of the post so you can see when to stop!<br /></p><p>Put the top of the post into the thumper, then stick the point into the ground and raise it up. Bonk the post in by raising and dropping the thumper 30 cm or so. Wedge the post with your foot
to help it go vertical.</p><p>Removing the thumper from the post can be tricky, since it is unbalanced with the big weight at the top, so it will likely drop onto the ground as soon as you clear the top of the post - try not to drop it on someone's foot! </p><p> </p><p> </p><p> </p><p>For driving a Sand Point Well Pipe into the ground, I built a tripod gantry with two pulleys, to make it easier to lift the thumper. </p><p> Here is a picture of the pipes about 2 meters into the ground:</p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh6LzfSRkoRaj0zWmesY_0cqjLcOnXbF6SCEW20qNISyF63aOUrNfmoW6BC3zI_06AWq056QWHvQXZyWKopuCpPbkW-ggg7wW0W4YlT9DUfypr9nbmtgB1adzbEpdF2ad_QxIezGxa8efW4kzQPtZviuRwiZ5r3-wrfVcLk8KqGOl12wS-2_0TgzHXO/s2179/wellpipe.jpg" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="2179" data-original-width="1605" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh6LzfSRkoRaj0zWmesY_0cqjLcOnXbF6SCEW20qNISyF63aOUrNfmoW6BC3zI_06AWq056QWHvQXZyWKopuCpPbkW-ggg7wW0W4YlT9DUfypr9nbmtgB1adzbEpdF2ad_QxIezGxa8efW4kzQPtZviuRwiZ5r3-wrfVcLk8KqGOl12wS-2_0TgzHXO/s320/wellpipe.jpg" width="236" /></a></div><br /> <br /><p></p><p> </p><p> </p><p> Only 5 meters more to go...<br /></p><p> </p><p> <br /></p><p>I'm sure the neighbours will be happy when I reach the end of my pipe.<br /></p><p> </p><p><br /></p><h3 style="text-align: left;"><b>Wheelies </b><br /></h3><p>Speaking of heavy stuff. I built some heavy garden gates and needed to drag them about 20 meters from the garage to the corner of the yard and my back was getting sore. <br /></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-ntqwDt_GBIY3vPtgTJnRIZ4ZPOq5oEWGpBCpCOm4XzGhEDu1KJVmDA35mZQ01IWz_-tF65sYkzvCpu3kbWGoJ9kKdLLuVVrfimpBWK61uhX5YultkMbFls5DJ7zoqy5oFHgjIuLPcrzFU6hsdoUiC6l6DL5PdGafDkDcxnq5Da1e7ykt1o3_lx8g/s1920/wheels.jpg" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1080" data-original-width="1920" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-ntqwDt_GBIY3vPtgTJnRIZ4ZPOq5oEWGpBCpCOm4XzGhEDu1KJVmDA35mZQ01IWz_-tF65sYkzvCpu3kbWGoJ9kKdLLuVVrfimpBWK61uhX5YultkMbFls5DJ7zoqy5oFHgjIuLPcrzFU6hsdoUiC6l6DL5PdGafDkDcxnq5Da1e7ykt1o3_lx8g/s320/wheels.jpg" width="320" /></a></div><br /><p>So, I re-invented <i>The Wheel</i>!</p><p>Two wheels close together, roll better over bumpy paving stones, than a single wheel.<i><br /></i></p><p><i>It only has to work twice. </i><br /></p><p><br /> </p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirovS3phgmZ-D3J4wq49kv28LJY_aNxaYo5GsKOCxu76bsbrnqlIUD81lenbHUJ7jrq-YK6x_peiymNgiea3iWbo__4VVndDS3zn7-sL19kT_YR2heJruauJ3_Q0v12lIgwJLRD6KvPUsE5DIod2HOlwEzrBTlkr9mmmMoKRDRm_PbQ3XSkCX5mqC6/s2016/table-wheels.jpg" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="2016" data-original-width="1512" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirovS3phgmZ-D3J4wq49kv28LJY_aNxaYo5GsKOCxu76bsbrnqlIUD81lenbHUJ7jrq-YK6x_peiymNgiea3iWbo__4VVndDS3zn7-sL19kT_YR2heJruauJ3_Q0v12lIgwJLRD6KvPUsE5DIod2HOlwEzrBTlkr9mmmMoKRDRm_PbQ3XSkCX5mqC6/s320/table-wheels.jpg" width="240" /></a></div><br /><p></p><p>The above wooden wheels turned out real good, so I made a couple more, to clamp on and drag random heavy things around, such as my work table - which is an old recycled kitchen table with strengthening around the legs.</p><p>Now I can tip it over and then just need to balance it a bit, when I drag it off to the storage area. I may cut another pair of wheels and screw them to the table permanently. <br /></p><p>For something that won't get hundreds of miles of use, scrap wood wheels are great and cost nothing - OK, you need a screw and two washers also, but that won't break the piggy bank.</p><p> </p><p> </p><p>A little wooden wheel, cut with a 50 mm hole saw, can make a nice low friction Garden Gate Support:</p><p></p><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1d_SvFYneVq4kDjJLNU1I0DZuTnqC3OEQLyHrmd-F53FUMN7YjSYr81lsnXWFspbI7-CV9HA2hG2v_vNW28T2xGFPUzH8AHdW0ltxAtr3KF-y8QmvUQgW5JCQo0uM5X9_KOz24FbukKnT_JIukyVsNfxTJFMHQNUinr4DpiYRW2R8__WFZiBisC4i/s3024/doorsupport.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2969" data-original-width="3024" height="314" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1d_SvFYneVq4kDjJLNU1I0DZuTnqC3OEQLyHrmd-F53FUMN7YjSYr81lsnXWFspbI7-CV9HA2hG2v_vNW28T2xGFPUzH8AHdW0ltxAtr3KF-y8QmvUQgW5JCQo0uM5X9_KOz24FbukKnT_JIukyVsNfxTJFMHQNUinr4DpiYRW2R8__WFZiBisC4i/s320/doorsupport.jpg" width="320" /></a></div><p><br />The roller and block (with a rounded corner) lifts the door a few mm, so that the sliding bolt lines up perfectly, making the gate easy to open/close. Don't glue the block - use two screws instead. When the system needs adjustment, unscrew the block and reposition it.</p><p>In total, I built five wooden garden gates and used Soudal Urethane Exterior glue. The gate frames are made with lap joints and 10 mm dowels. The inside panels were simply glued in with lap joints and no dowels. After 2.5 years the panel planks started to pop out on the gate that is opened and closed the most - it gets the most flexing and slamming and the glue eventually failed. So then I had to drill a couple hundred 6 mm dowel holes from the insides of the gates, to leave the street sides unspoiled. After some sanding and painting no one will be the wiser. </p><p>With a task like this, applying glue to the dowels is a big chore, and getting glue on your fingers is best avoided - makes your skin awfully dirty looking. I screwed a plastic lid to a block of wood and put a piece of wire across it. Filled with a puddle of glue, I then used long nose pliers to dip/roll the dowels in the glue and scrape the excess glue off and then stick them in the holes, followed by a little hammer tap and Bob's yer Uncle. The trick is making the excess glue drip back, instead of dripping on the floor...<br /></p><p>On the whole, my conclusion is that Soudal Exterior Urethane glue is pretty good, but all joints should have some cross connects such as dowels for further mechanical strength.<br /></p><p>La voila!</p><p>Herman<br /></p><p></p>Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com0tag:blogger.com,1999:blog-1589959253862674712.post-75988543271794679372022-05-08T16:49:00.010+02:002022-07-30T20:29:04.875+02:00Sawz<div><h3 style="text-align: left;"><b>Simple Table Saw </b><br /></h3><p>To me, much of the fun of woodworking is making my own tools and jigs and then using them in a project. Jigs made of wood do not last very long, since they either wear out, or warp (or both!), so making new jigs is a constant process. The trick is to keep it simple, so that any worn or damaged guide piece can be replaced quickly with whatever is in your scrap wood bin.<br /></p><p></p><p></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEio35xcnrRGrgc5HBeCKI9I42HVDqAQgYWOmxETI7dqJsXyd1t8qcnsE9V9WUSaAqd6j4IFX9ugLiBYc7P3tAClkVpTOEUqHlQRZGPT9ZbAJHrSpl8BjhLeyWaQHm69kBToWlJMtOFi19ar_6V-JBAIlIQP9YwViD1NtCmz-WUvZytRB4MayPAAeElo/s2016/saw.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1512" data-original-width="2016" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEio35xcnrRGrgc5HBeCKI9I42HVDqAQgYWOmxETI7dqJsXyd1t8qcnsE9V9WUSaAqd6j4IFX9ugLiBYc7P3tAClkVpTOEUqHlQRZGPT9ZbAJHrSpl8BjhLeyWaQHm69kBToWlJMtOFi19ar_6V-JBAIlIQP9YwViD1NtCmz-WUvZytRB4MayPAAeElo/s320/saw.jpg" width="320" /></a></div><p style="text-align: center;"><i><b>Table Saw With Guide</b></i><br /></p><p>When machining large pieces of wood, it is best to keep the wood still and move the machine, so a hand circular saw is a must have. However, when working small pieces of wood, it is best to keep the machine still and move the wood, so a table saw is also a must have. A table saw can however be rather expensive and a cheap, inaccurate, wobbly one, costs 3 times more than a hand tool.</p><p style="text-align: left;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1TFaUKECMv8t8ghcooy0VxxMNw7fn1FYEibWno1bBDM0BTnp11GXFhvJB7zbzHg3vpDhs6snPkFGB9eevLDVPzWcZaD3GDZkB_qj4drxHrBifvq5jxT1zDtHQytZ5_i7F_Atl7MhmQPh5oTU_sz-t0xeI2XYKYInWz5pkYvRoyJO_Q85WrJPUQMje/s2016/guide.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2016" data-original-width="1512" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1TFaUKECMv8t8ghcooy0VxxMNw7fn1FYEibWno1bBDM0BTnp11GXFhvJB7zbzHg3vpDhs6snPkFGB9eevLDVPzWcZaD3GDZkB_qj4drxHrBifvq5jxT1zDtHQytZ5_i7F_Atl7MhmQPh5oTU_sz-t0xeI2XYKYInWz5pkYvRoyJO_Q85WrJPUQMje/s320/guide.jpg" width="240" /></a></div><p></p><p style="text-align: center;"><i><b>Table Saw Saw Guide </b></i><br /></p><p>Making your own table saw with an upside down hand saw is not difficult and it also has some advantages, notably that cutting through the table results in a zero clearance blade slot, which helps to reduce tear-out. I set the blade to 90 degrees and leaves it that way. I never cut at an angle with a circular saw, since it much increases the danger of a jam and kickback, which can hurt very badly. I rather use a jigsaw for fancy cuts.</p><p>When selecting a circular saw, compare the different models on display and select the one with the sturdiest guide plate chassis. <i>The biggest problem with DIY tools is wobble. </i> Makita saws are very sturdy, while my other cheap American saw is rather wobbly, so I learned from the experience.<br /></p><p>I made an Ikea scrap wood MDF box with a top and no bottom, to house the saw. To adjust the blade height, I tip the box up to get to the lever and since there is no bottom, saw dust falls out and doesn't build up in the box. However, it is a good idea to cut a hole in the side for a vacuum cleaner nozzle, to reduce the dust flying up into the air.<br /></p><p> <br /></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhLpJQFiqh3oGrws0PDzhf6PmVBPjos4jZNEx5h3n9r8TtuJoawlGGMJBCwmpURej4TGGCx6LZGCuqLSRG4ogQu7UAZxJsvgg1T9w51J36P3OmQgwkuhYVdTsLhWn2XJ3_IMSjMXk8dJGGKhzJ8gmdFbvgfPzPTzhfTZ0UhAOrOxygyhtVYP0XdZIAs/s2016/box.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1512" data-original-width="2016" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhLpJQFiqh3oGrws0PDzhf6PmVBPjos4jZNEx5h3n9r8TtuJoawlGGMJBCwmpURej4TGGCx6LZGCuqLSRG4ogQu7UAZxJsvgg1T9w51J36P3OmQgwkuhYVdTsLhWn2XJ3_IMSjMXk8dJGGKhzJ8gmdFbvgfPzPTzhfTZ0UhAOrOxygyhtVYP0XdZIAs/s320/box.jpg" width="320" /></a></div></div><p style="text-align: center;"><i><b>Upside Down Table Saw<br /></b></i></p><p style="text-align: left;">When using the table saw, I clamp a piece of wood to the back of my work table, to keep the saw box from sliding off. That works well enough.<b><br /></b></p><h3 style="text-align: left;"><b>Simple Saw Guides </b><br /></h3><p>The top overhangs the sides of the box by 5 cm, to enable the use of simple guide blocks and clamps. <br /></p><p>The saw rip guide (<i>Yankees call it a fence</i>) slides along the front side, wraps around the table edge and clamps in place. <i>The guide ends at the middle of the blade.</i> At that point, the wood is cut, a longer guide doesn't help anymore and could cause the wood to jam between the guide and the blade and get flung back at high speed, which will hurt badly, so I keep the guide short. American table saws have guides that go all the way to the back of the table - that is <i>not</i> a good idea. </p><p><i>When you make the rip guide, glue the pieces, then clamp them to the blade and the front edge of the table. By doing that, the guide is guaranteed to be perfectly parallel to the blade, even if the table edge is not. </i>Once the glue set, you can add a couple of screws if needed.<br /></p><p>Yootoob is full of fancy saw guide designs. If you make a fancy guide, then when it breaks and/or warps, you need to spend a lot of time making a new one. So I keep it simple, don't make fancy sliding slots in the table top and use a G clamp to secure my saw guides to the table edges. A saw guide could be as simple as a piece of junk wood that was lying around, or a plastic rafter square. <br /></p><p><i>To use a saw rip guide, clamp it lightly with a G clamp to the table edge and adjust it with a rubber mallet, then tighten the clamp.</i></p><p>I cut with the blade set much higher than the wood thickness. This directs the cutting force mostly into the table and not at me, which reduces splintering and also reduces dangerous fly-back of wood pieces. <i>It is a good idea to use a smaller size circular saw (a 5 to 7 inch blade is enough) with less power.</i> You will never be sorry if your puny little 5 inch table saw jams and stalls - while you will be very sorry for yourself if your saw goes <i>Whump</i>! and throws the wood piece back to you at 100 miles an hour. <i> </i></p><p><i>A ten inch table saw is a killer - A bigger table saw isn't better! </i></p><h3 style="text-align: left;">Table Saw Cross Cut / Mitre Jig<br /></h3><p>A table saw cross cut sled is very useful. I made one from scrap wood, that fits over the table saw box, guided by the edges. </p><p style="text-align: left;"></p><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgbDu5kEn0bJD-CMwa1yxUmuqYEjj-HMNeQVLoh98Gz9QxBxjTwL6T_tCTQbZXxxUBk5-B8PYwsAiirDI1-qdJu2UNbfYxoVJqNWTG34XXee9UGPFhIFQVEcRl3IF_j7s-Gk1Tpjp-ZG9DTNq9hs0KQczbbBdrXIIUvAO9Vm8PFCXuMvs9GPmrTYbJ7/s2016/cross-cut-jig.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1512" data-original-width="2016" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgbDu5kEn0bJD-CMwa1yxUmuqYEjj-HMNeQVLoh98Gz9QxBxjTwL6T_tCTQbZXxxUBk5-B8PYwsAiirDI1-qdJu2UNbfYxoVJqNWTG34XXee9UGPFhIFQVEcRl3IF_j7s-Gk1Tpjp-ZG9DTNq9hs0KQczbbBdrXIIUvAO9Vm8PFCXuMvs9GPmrTYbJ7/s320/cross-cut-jig.jpg" width="320" /></a></div><i><b></b></i><p></p><p style="text-align: center;"><i><b>Table Saw Cross Cut Jig </b></i><br /></p><p>When you glue up such a jig, put two layers of masking tape on the edges, to ensure that after you glued it, it will not stick to the table and there will be enough clearance to slide smoothly when you remove the tape. Some wax will also help to make it move and keep it from warping as soon as you want to use it.<br /></p>For miter cuts, I clamp a triangle to it. For multiple cut offs, I use a G clamp with a stop block.<br /><h3 style="text-align: left;"><b>Hand Saw Cross Cut Sled </b> </h3><p>Another jig I use a lot, is a cross cut sled for my hand saw. The guide rails are left over oak edging. Put some wax on them.<br /></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgbgi0VVVIde2XwXbvFn_UMVOjlMBUYBFfbsPyJZY0t0COXcDpjgMejb3FwFidrrWpeDXPtQFQfrtJg64hdukRythvf9-aIIdS3fe9Xrn65LHDxsK1VoSJ9frtKeDt5upJPOWeDCAqfESp0TwXstB-FchmOXG9OZbmq8ChaJN8sJO04qQVMa-pspM6k/s2016/croscut.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2016" data-original-width="1512" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgbgi0VVVIde2XwXbvFn_UMVOjlMBUYBFfbsPyJZY0t0COXcDpjgMejb3FwFidrrWpeDXPtQFQfrtJg64hdukRythvf9-aIIdS3fe9Xrn65LHDxsK1VoSJ9frtKeDt5upJPOWeDCAqfESp0TwXstB-FchmOXG9OZbmq8ChaJN8sJO04qQVMa-pspM6k/s320/croscut.jpg" width="240" /></a></div><p style="text-align: center;"><i><b>Cross Cut Sled </b></i><br /></p><p>If I need a 45 degree cut, I simply clamp a plastic rafter square to the base. <i>Don't ever use a steel square as a cutting guide</i>. I would not like to accidentally cut into a steel square - the result of tungsten saw teeth binding into a steel tool won't be fun at all. This sled has seen heavy use over the past year.</p><h3 style="text-align: left;">The Simplest Jigsaw Guide Ever<br /></h3><p>There are many videos on Yootoob showing how to turn a jigsaw with a long flexible blade into something resembling a band saw, by using a wooden overhead arm and ball bearings. <i>You don't need any of that. </i> <i> </i></p><p><i>Simply buy Professional quality blades.</i> It is the same type of blade you always buy, but with a <i>P</i> at the end of the part number. Those blades are thick and stiff. They don't flex and they cut straight!</p><p style="text-align: left;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjcAmPmW2hCsWuRED2pJxCnCjN5RemUJihhfk9jZlWmIjRkcMGEjwdS8ESOiuTSCLgDUghiFSUPonyermKraOSpeI-SgVMCpBbMbk54ahvONpCT7Le8Um6thKfERzIUt3vJPYg4Ct9sCyRLZhiF6W1cpwYGDLEcUQJJg48McZhvYmJgvOLHpvRRquUG/s2016/jigsaw.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1512" data-original-width="2016" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjcAmPmW2hCsWuRED2pJxCnCjN5RemUJihhfk9jZlWmIjRkcMGEjwdS8ESOiuTSCLgDUghiFSUPonyermKraOSpeI-SgVMCpBbMbk54ahvONpCT7Le8Um6thKfERzIUt3vJPYg4Ct9sCyRLZhiF6W1cpwYGDLEcUQJJg48McZhvYmJgvOLHpvRRquUG/s320/jigsaw.jpg" width="320" /></a></div><b></b><p></p><p style="text-align: center;"><b>Jig Saw with Dust Port and Professional Blade</b><br /></p><p>Here is a picture of my little jigsaw, with a professional blade and a conical PVC rubber adaptor for the little 21 mm dust port to fit a vacuum cleaner hose. You can get the conical widgets on Amazon in packs of 2 to 5. Do yourself a favour and buy a bunch of them.<br /></p><p>La voila</p><p>Herman.<br /></p>Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com0tag:blogger.com,1999:blog-1589959253862674712.post-26272448072999239392022-01-11T11:35:00.017+01:002022-01-12T20:57:38.650+01:00Linux Security Cameras<p><b>Security Camera Management Programs</b><br /></p><p>There are two decent Linux programs for managing security cameras: <i>Motion</i> and <i>ZoneMinder</i>.</p><p>For test purposes, I set a camera up inside my living room. Once working, I'll install two outside, to watch the driveway and backyard. <br /></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEhKzTs7NmJJoXSniSVUgC23-OsPCobBZy1PBiQLUrqPrHcq-v5-kumsM7R5OF6YNw_yppTdgfZm4FMB0zDrPilihq5cUo6EHUWhojycLnUIJJOWYRFerCuZ7qMwATMmD62shaq0goA_aUW0XsvQYIXAICwUUYspbiENDB04XvbTIT0dsKN9WOfwnA7X=s1360" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="768" data-original-width="1360" height="226" src="https://blogger.googleusercontent.com/img/a/AVvXsEhKzTs7NmJJoXSniSVUgC23-OsPCobBZy1PBiQLUrqPrHcq-v5-kumsM7R5OF6YNw_yppTdgfZm4FMB0zDrPilihq5cUo6EHUWhojycLnUIJJOWYRFerCuZ7qMwATMmD62shaq0goA_aUW0XsvQYIXAICwUUYspbiENDB04XvbTIT0dsKN9WOfwnA7X=w400-h226" width="400" /></a></div><p></p><p style="text-align: center;"> <b>Streaming Camera with Fish Eye Lens</b><br /></p><i>Motion</i> is the simpler one of the two programs, but with almost 300 configurable options, it can do anything worth doing. It works just as well as <i>ZoneMinder</i>, but it simply doesn't do things that are not needed. For example, Motion supports a database, but Linux filesystem storage is usually good enough. It doesn't have a fancy GUI, since it is intended to run on a server, stashed on a shelf in a dark corner. There is a GUI which can be accessed with a web browser locally, or over the LAN, but I never used it. One can also view real-time streams with a web browser. Notifications can be sent and files uploaded to another machine with external programs such as <i>mutt</i>, <i>wput</i> and others.<br /><p>While one can watch a TP Link security camera with a cell phone App, I want to
monitor what is going on when not at home, without spending money on a subscription service. The simplest way to do this, is to use a free email account as an archive. Wherever I travel, I can log into <i>gmail</i> with a web browser and look at the stored security videos, to confirm that my house hasn't burned down and that there isn't an old Baba Yaga with a black cat and a white goat staying there.<br /></p><p>In this guide, I describe how to configure <i>Motion</i> to handle a <i>TP-Link C100</i> RTSP streaming camera and email a short video clip whenever motion is detected, using <i>mutt</i> with a <i>gmail</i> account.</p><p><b>Install Motion and Mutt</b></p><p><i>Mutt</i> is a simple command line mail client which is fully supported and updated by Ubuntu Linux. It provides the ability to send attachments using a free mail account from <i>gmail</i>, <i>yahoo</i> or similar service.<b> </b>The parameter syntax of <i>mutt</i> is a little wonky - do yourself a favour and read the man page at least 3 times.<b><br /></b></p><ul style="text-align: left;"><li><i>$ sudo su -</i></li><li><i>password <br /></i></li><li><i># apt install motion mutt ffmpeg <br /></i></li></ul><p><b>Streaming Cameras</b></p><p>First of all, get the <i>TP-Link</i> camera to work. You need to install an App on your cell phone to do that. Using this App, <i>create a user account</i> with a <i>password</i> to use for the RTSP stream login. With the App, you can also find the camera <i>IP address</i> - or look in your router DHCP list for it.</p><p>Use <i>ffplay</i> to verify that you can log in and play the camera streams:</p><ul style="text-align: left;"><li><i>$ ffplay rtsp://USERNAME:PASSWORD@IP.ADD.RE.SS/stream1</i></li></ul><p>The above is the EXACT string that you need to use later in the camera configuration. <i><br /></i></p><b>Security Considerations </b><br /><p>For improved security, I configured mutt and motion to run under my user account on an Ubuntu Linux server.</p><p><b>Configure Mutt </b><br /></p><ul style="text-align: left;"><li>$ cd</li><li>$ mkdir .mutt</li></ul><p>Create a new <i>gmail</i> account for the security system, then go to the account security settings and set <b><i>Support for Less Secure Apps ON. </i></b> Otherwise <i>mutt</i> will be blocked by Google.<b><i> </i></b>Simply send the attachments to this <i>gmail</i> address and leave it all there. Don't clog up your regular email account with security cam spam. When Google eventually complains that the mailbox is full (you get 15GB for free), you can simply select all and delete it, then let it fill up again.<br /></p><p>Create a file called <i>mutrc</i>.</p><p>Replace <i>USERNAME</i>, <i>REAL NAME</i> and <i>PASSWORD</i> with the exact details used when creating the <i>gmail</i> account. <b><i>Put SINGLE QUOTES around the password to prevent the expansion of any $ signs in the password.</i></b><br /></p><p style="margin-left: 40px; text-align: left;"><i>set from = "USERNAME@gmail.com"<br />set realname = "REAL NAME"<br />set imap_user = "</i><i><i>USERNAME</i>@gmail.com"<br />set imap_pass = 'PASSWORD'<br />set smtp_url = "smtps://</i><i><i>USERNAME</i>@smtp.gmail.com"<br />set smtp_pass = '</i><i><i>PASSWORD</i>'<br />set folder = "imaps://imap.gmail.com/"<br />set spoolfile = "+INBOX"<br />set postponed="+[Gmail]/Drafts"<br />set trash = "+[Gmail]/Trash"</i><br /></p><p><b>Configure Motion </b><br /></p><ul style="text-align: left;"><li>$ cd <br /></li><li>$ mkdir .motion</li><li>$ cd .motion</li><li>$ cp /etc/motion/motion.conf .</li><li>$ cp /etc/motion/camera* .</li></ul><p><b>Motion.conf </b><br /></p><p>Make a file called <i>motion.conf</i>. In the below example change USERNAME to suit.<br /></p><p style="text-align: left;"><i># Rename this distribution example file to motion.conf</i><br /><i>#</i><br /><i># This config file was generated by motion 4.3.2</i><br /><i># Documentation: /usr/share/doc/motion/motion_guide.html</i><br /><i>#</i><br /><i># This file contains only the basic configuration options to get a</i><br /><i># system working. There are many more options available. Please</i><br /><i># consult the documentation for the complete list of all options.</i><br /><i>#</i><br /><br /><i>############################################################</i><br /><i># System control configuration parameters</i><br /><i>############################################################</i><br /><br /><i># Start in daemon (background) mode and release terminal.</i><br /><i>daemon off</i><br /><br /><i># Start in Setup-Mode, daemon disabled.</i><br /><i>setup_mode off</i><br /><br /><i># File to store the process ID.</i><br /><i>pid_file /home/</i><i><i>USERNAME</i>/.motion/pid</i><br /><br /><i># File to write logs messages into. If not defined stderr and syslog is used.</i><br /><i>log_file /home/</i><i><i>USERNAME</i>/.motion/motion.log</i><br /><br /><i># Level of log messages [1..9] (EMG, ALR, CRT, ERR, WRN, NTC, INF, DBG, ALL).</i><br /><i>log_level 6</i><br /><br /><i># Target directory for pictures, snapshots and movies</i><br /><i>target_dir /home/USERNAME/Videos</i><br /><br /><i># Video device (e.g. /dev/video0) to be used for capturing.</i><br /><i>;videodevice /dev/video0</i><br /><br /><i># Parameters to control video device. See motion_guide.html</i><br /><i>; vid_control_params value</i><br /><br /><i># The full URL of the network camera stream.</i><br /><i>; netcam_url value</i><br /><br /><i># Name of mmal camera (e.g. vc.ril.camera for pi camera).</i><br /><i>; mmalcam_name value</i><br /><br /><i># Camera control parameters (see raspivid/raspistill tool documentation)</i><br /><i>; mmalcam_control_params value</i><br /><br /><i>############################################################</i><br /><i># Image Processing configuration parameters</i><br /><i>############################################################</i><br /><br /><i># Image width in pixels.</i><br /><i>width 1920</i><br /><br /><i># Image height in pixels.</i><br /><i>height 1080</i><br /><br /><i># Maximum number of frames to be captured per second.</i><br /><i>framerate 2</i><br /><br /><i># Text to be overlayed in the lower left corner of images</i><br /><i>text_left "CAM1"</i><br /><br /><i># Text to be overlayed in the lower right corner of images.</i><br /><i>text_right %Y-%m-%d\n%T-%q</i><br /><br /><i>############################################################</i><br /><i># Motion detection configuration parameters</i><br /><i>############################################################</i><br /><br /><i># Always save pictures and movies even if there was no motion.</i><br /><i>emulate_motion off</i><br /><br /><i># Threshold for number of changed pixels that triggers motion.</i><br /><i>;threshold 1500</i><i> </i></p><p style="text-align: left;"><i>threshold 10000</i><br /><br /><i># Noise threshold for the motion detection.</i><br /><i>noise_level 32</i><br /><br /><i># Despeckle the image using (E/e)rode or (D/d)ilate or (l)abel.</i><br /><i>despeckle_filter EedDl</i><br /><br /><i># Number of images that must contain motion to trigger an event.</i><br /><i>minimum_motion_frames 1</i><br /><i>;minimum_motion_frames 5</i><br /><br /><i># Gap in seconds of no motion detected that triggers the end of an event.</i><br /><i>event_gap 10</i><br /><br /><i># The number of pre-captured (buffered) pictures from before motion.</i><br /><i>pre_capture 3</i><br /><br /><i># Number of frames to capture after motion is no longer detected.</i><br /><i>post_capture 0</i><br /><br /><i>############################################################</i><br /><i># Script execution configuration parameters</i><br /><i>############################################################</i><br /><br /><i># Command to be executed when an event starts.</i><br /><i>; on_event_start value</i><br /><br /><i># Command to be executed when an event ends.</i><br /><i>; on_event_end value</i><br /><i> </i><br /><i># Command to be executed when a movie file is closed.</i><br /><i>; on_movie_end value</i><br /><i>on_movie_end "echo '</i><i><i>S</i>ecurity video'|mutt -i - -s 'Security Video'</i><i> -a "/home/</i><i><i>USERNAME</i>/Videos/CAM1-%t-%v-%Y%m%d%H%M.mkv" -- </i><i><i>USERNAME</i>@gmail.com"</i><br /><br /><i>############################################################</i><br /><i># Picture output configuration parameters</i><br /><i>############################################################</i><br /><br /><i># Output pictures when motion is detected</i><br /><i>picture_output off</i><br /><br /><i># File name(without extension) for pictures relative to target directory</i><br /><i>picture_filename %Y%m%d%H%M%S-%q</i><br /><i>;picture_filename %Y%m%d%H%M-%q</i><br /><br /><i>############################################################</i><br /><i># Movie output configuration parameters</i><br /><i>############################################################</i><br /><br /><i># Create movies of motion events.</i><br /><i>movie_output on</i><br /><br /><i># Maximum length of movie in seconds.</i><br /><i>movie_max_time 20</i><br /><br /><i># The encoding quality of the movie. (0=use bitrate. 1=worst quality, 100=best)</i><br /><i>movie_quality 45</i><br /><br /><i># Container/Codec to used for the movie. See motion_guide.html</i><br /><i>movie_codec mkv</i><br /><br /><i># File name(without extension) for movies relative to target directory</i><br /><i>movie_filename %t-%v-%Y%m%d%H%M%S</i><br /><i>;movie_filename %t-%v-%Y%m%d%H%M</i><br /><br /><i>############################################################</i><br /><i># Webcontrol configuration parameters</i><br /><i>############################################################</i><br /><br /><i># Port number used for the webcontrol.</i><br /><i>webcontrol_port 8080</i><br /><br /><i># Restrict webcontrol connections to the localhost.</i><br /><i>webcontrol_localhost on</i><br /><br /><i># Type of configuration options to allow via the webcontrol.</i><br /><i>webcontrol_parms 0</i><br /><br /><i>############################################################</i><br /><i># Live stream configuration parameters</i><br /><i>############################################################</i><br /><br /><i># The port number for the live stream.</i><br /><i>stream_port 8081</i><br /><br /><i># Restrict stream connections to the localhost.</i><br /><i>stream_localhost on</i><br /><br /><i>##############################################################</i><br /><i># Camera config files - One for each camera.</i><br /><i>##############################################################</i><br /><i>camera /home/</i><i><i>USERNAME</i>/.motion/camera1.conf</i><br /><i>; camera /usr/etc/motion/camera2.conf</i><br /><i>; camera /usr/etc/motion/camera3.conf</i><br /><i>; camera /usr/etc/motion/camera4.conf</i><br /><br /><i>##############################################################</i><br /><i># Directory to read '.conf' files for cameras.</i><br /><i>##############################################################</i><br /><i>; camera_dir /usr/etc/motion/conf.d</i><br /></p><p style="text-align: left;"><b>Camera1.conf </b><br /></p><p style="text-align: left;">Make a file called camera1.conf. Set the picture size according to your camera resolution.</p><p style="text-align: left;"></p><p style="text-align: left;"></p><p style="text-align: left;"></p><p style="text-align: left;">Set the USERNAME and PASSWORD to the RTSP stream account that you created in the camera App.</p><p style="text-align: left;"><i># /usr/etc/motion/camera1.conf<br />#<br /># This config file was generated by motion 4.3.2<br /><br />###########################################################<br /># Configuration options specific to camera 1<br />############################################################<br /># User defined name for the camera.<br />camera_name CAM1<br /><br /># Numeric identifier for the camera.<br />camera_id 101<br /><br /># The full URL of the network camera stream.<br />netcam_url rtsp://USERNAME:PASSWORD@10.10.10.78/stream1<br /><br /># Image width in pixels.<br />;width 1280<br />width 1920<br /><br /># Image height in pixels.<br />;height 720<br />height 1080<br /><br /># Text to be overlayed in the lower left corner of images<br />text_left CAM1<br /><br /># File name(without extension) for movies relative to target directory<br />;movie_filename CAM1_%t-%v-%Y%m%d%H%M%S<br />movie_filename CAM1-%t-%v-%Y%m%d%H%M </i></p><p style="text-align: left;">Ditto for Camera 2. <b><br /></b></p><p style="text-align: left;"><b>Motion Configuration Tricks</b></p><p style="text-align: left;">Enable the Despeckle filter to reduce the amount of motion events. Set the maximum length of the movie clip to 20 seconds, to keep the file smallish and ensure that the email system will accept it. </p><p style="text-align: left;">Remove the seconds parameter from the file names, since the system is already processing the next event when the current event is handled, which makes it impossible to attach the correct file down to the second. Sometimes there will still be a problem when the minutes roll over, but most video files will get sent successfully.<br /></p><p style="text-align: left;">Always specify the complete filename path.</p><p style="text-align: left;"><b>Email Test</b></p><p style="text-align: left;">First test <i>mutt</i> interactively. Run it from the console and play with it to ensure that you can send and receive email and that <i>gmail is not blocking it</i>. </p><p style="text-align: left;"><b>Motion Test</b></p><p style="text-align: left;">Run <i>motion</i> from the command line and play with it, to ensure that it works properly and will send emails with <i>mutt</i>. If you get too many messages, increase the pixel change trigger level.</p><p>You need to find a happy medium where the system will not email a deluge of messages, since Google will block the account if you do. If you find that there is just too much movement in your situation, then you could also use the <i>snapshot</i> feature to email a picture once per hour or so and leave the movies on your home server.</p><p>Another option is to make the event gap much longer, so that it will detect motion, but not all motion.<br /></p><p style="text-align: left;">You can view the real time video with a web browser on port 8081:<br /></p><ul style="text-align: left;"><li><i>$ firefox http://localhost:8081/101 </i></li></ul><p style="text-align: left;"><b>Mailbox Cleanup</b></p><p style="text-align: left;">Deleting a few thousand messages manually using <i>gmail</i> with a webbrowser, would be extremely tedious. When the mailbox gets full, it may be easier to delete the account and create a new one.<br /></p>To clean the gmail box in one swell foop, you can try the following command with mutt:<br /><ul style="text-align: left;"><li>mutt -e "push D~d>30d<enter>qy<enter>"</li></ul>However - it may cause Google to disable your mail account for an hour, since this kind of mass mail delete with the IMAP protocol may look suspicious to their system. <br /><br /><br />La voila!<p style="text-align: left;">Herman<br /></p><p style="text-align: left;"><br /></p>Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com2tag:blogger.com,1999:blog-1589959253862674712.post-14558577138457133372021-10-20T15:38:00.009+02:002021-10-20T16:08:20.053+02:00Copy a Linux ISO image to a USB nurgle on a Mac<p>On a Mac, a simple thing such as copying an ISO file to a USB nurgle, is not necessarily simple, due to the helpful automounter. </p><p>Get a Linux ISO image over here: <a href="https://ubuntu.com/download/flavours">https://ubuntu.com/download/flavours</a> </p><p> <br /></p><h3 style="text-align: left;"><b>Open a terminal, then do the following</b><br /></h3><p>See which disks are on the machine: <br /></p><ul style="text-align: left;"><li>$ <i>diskutil list</i><br /></li></ul><p>Insert the USB nurgle, to see the disk node (Likely <i>/dev/disk2</i> - <i>NEVER disk1!!!</i>):</p><ul style="text-align: left;"><li>$ <i>diskutil list</i></li></ul>Unmount the nurgle:<br /><ul style="text-align: left;"><li>$ <i>diskutil unmountDisk /dev/diskN</i> </li></ul> Copy the ISO file to the USB nurgle: <ul style="text-align: left;"><li>$ <i>sudo dd if=/path-to.iso of=/dev/diskN bs=1m</i></li></ul><p>Once completed:</p><ul style="text-align: left;"><li>$ <i>diskutil eject /dev/diskN</i></li></ul><p><br /></p><h3 style="text-align: left;">Caution<br /></h3><p><b><i>Please note that writing to /dev/disk1 will very likely be extremely disappointing, so rather don't. </i></b></p><p><br /></p><h3 style="text-align: left;">Eh?<br /></h3><p><i>What is a <b>nurgle</b>??? </i></p><p><i>It is Aussie for a widget, a thingummabob, a whatchammacallit, a whassisname, or a hoosammawhatsit - a very versatile word to add to your technojargon vocabulary.<br /></i></p><p><br /></p><p>La voila!</p><p>Herman <br /></p>Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com0tag:blogger.com,1999:blog-1589959253862674712.post-59722938998294150262021-04-08T14:36:00.003+02:002021-10-20T15:39:45.790+02:00Unlock CRA PDF Forms<h3 style="text-align: left;">Unlock Canada Revenue Agency PDF Forms</h3><p>It appears that there is a relatively new PDF feature to prevent casual copying and saving of a file and that some programs save PDF files with these foolish features active by default. Many forms from the Canada Revenue Agency are locked in this way, which makes it difficult to do one's taxes, since one can fill the form, but cannot save it. <br /></p><p style="text-align: left;"></p><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg3n37o8aBMQWO_bHScRS2bT-EDLOkSjhhSrjzpjt2g1LRD5YslbYXzsl6tW3Ma0KHi43n4vRYcMthfEEMg2zUfxSWnitKHJXb3FUcB5Nn_IoRcL3fp2D9m01q4ZN2kkdYxnVHzobxaWao/s846/Screen+Shot+2021-04-08+at+2.26.18+PM.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="262" data-original-width="846" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg3n37o8aBMQWO_bHScRS2bT-EDLOkSjhhSrjzpjt2g1LRD5YslbYXzsl6tW3Ma0KHi43n4vRYcMthfEEMg2zUfxSWnitKHJXb3FUcB5Nn_IoRcL3fp2D9m01q4ZN2kkdYxnVHzobxaWao/s320/Screen+Shot+2021-04-08+at+2.26.18+PM.png" width="320" /></a></div><p></p><p>One can only print the form. It should be possible to print to a file or export it to a new PDF file, but it is far better to reset the annoying anti-taxpayer flags, since the 'printed' form cannot be edited easily any more and I always manage to make a mistake or three that need to be corrected after review.<br /></p><p>If there is a Linux (virtual) machine handy, install <i>qpdf</i> and use it to reset the silly flags:</p><ul style="text-align: left;"><li><i>$ su -</i></li><li><i>password</i></li><li><i># dnf update</i></li><li><i># dnf install qpdf</i></li><li><i># exit</i></li><li><i>$ qpdf --decrypt lockedfile.pdf unlockedfile.pdf</i></li></ul><p>One doesn't need a password to unlock these flags, so the fix is instant.</p><p>La voila!</p><p>Herman <br /></p><p><br /></p>Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com0tag:blogger.com,1999:blog-1589959253862674712.post-38542380917165740302021-04-02T20:46:00.019+02:002022-08-20T20:38:02.376+02:00Bucket Vacuum Cleaner<h3 style="text-align: left;"><b>Bucket Vacuum Cleaner for Shop and Yard Work<br /></b></h3><p>I needed to clean out 50 years of cobwebs and dirt from two garages and a shed. The cobwebs were like a Hollywood horror movie and I needed to enter the shed armed with a broom and a shotgun. A little 1000 Watt home vacuum cleaner would be instantly full, so I disassembled an old one and mounted the parts on top of a big bucket from the Hornbach hardware store, to give the little sucker a fighting chance. All the surplus Covid filter masks also came in handy in the shed while cleaning.</p><h3 style="text-align: left;"><b>It Takes Two to Tango!</b><br /></h3><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEinudPN2WUtN4-1NTECWBxYBcnNBCV-rvJWJv217Fl6t-Q8yib6T5Quq3u77RD9VyJ7bqEFgcXQFXS9T6GG3s1tktRg1zixWprOGvDD-bv-g7jpXrDdpJrWEqZGaYTCrXE1tCX-af2-uK8/s2016/SuperSlurp.jpg" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="2016" data-original-width="1512" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEinudPN2WUtN4-1NTECWBxYBcnNBCV-rvJWJv217Fl6t-Q8yib6T5Quq3u77RD9VyJ7bqEFgcXQFXS9T6GG3s1tktRg1zixWprOGvDD-bv-g7jpXrDdpJrWEqZGaYTCrXE1tCX-af2-uK8/w300-h400/SuperSlurp.jpg" width="300" /></a></div><p><i>The trick is to use <b>two</b> buckets, one inside another, like two paper cups, otherwise the bucket can collapse when the pipe clogs up. Screw the outer bucket to the castor wheel plate, then you can simply remove the light weight inner bucket only, to empty the cleaner.<br /></i></p><p>The most difficult part of this project, is to disassemble the old cleaner. Evil one-time snaps and hidden little screws, may require using a wrecking bar and hack saw to pry the thing apart. </p><p>A home vac is a very simple device with essentially just <i>one</i> part - the motor-compressor unit. </p><p>The one I took apart also had a triac speed control, so that went into a little wooden box. I turned the speed down just a tad, to reduce the turbine screaming a bit. I've been wondering whether one could just stick a diode in series with an overpowered universal motor to slow it down to a more acceptable noise level, but that may damp it too much.<br /></p><h3 style="text-align: left;"><b>Holy Straps </b><br /></h3><p>The motor is simply held down with three pieces of <i>rigid strapping</i> (a holy metal strip, normally used to tie roof rafters together), on top of the original rubber gasket. Cover any exposed wiring with self vulcanizing tape, or hot glue, to keep you from dancing on the ceiling if you would touch it. Mount a round cartridge air filter (from a large truck engine or another kind of shop vac) under the motor on the inside of the lid. I again used some rigid strapping, washers and screws and a Stonehenge like ring of dowels to keep the filter cartridge in place. To clean the filter when the vac doesn't want to suck any more, simply toss it high up into the air in the back garden a few times, when the neighbours are not around.<br /></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEguEienY1YYOfIAKw410HhyphenhyphenlIYVfXA8vVdGuGMBauOlc1ZWYBYDgj76v53Wk2WhARXt7T1ZdeKwrhO6T0SJ8iorlamUIeKgRZeIPV1epmuwxy-Ex6gkHVs5tGB8nCKT45ULqZkwhtgL7VM/s520/Screen+Shot+2021-04-10+at+11.47.04+AM.png" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="512" data-original-width="520" height="197" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEguEienY1YYOfIAKw410HhyphenhyphenlIYVfXA8vVdGuGMBauOlc1ZWYBYDgj76v53Wk2WhARXt7T1ZdeKwrhO6T0SJ8iorlamUIeKgRZeIPV1epmuwxy-Ex6gkHVs5tGB8nCKT45ULqZkwhtgL7VM/w200-h197/Screen+Shot+2021-04-10+at+11.47.04+AM.png" width="200" /></a></div><p></p><p>The suction pipe was semi-permanently glued into a hole in the lid with construction glue. If your old vacuum cleaner still has a functional pipe attachment mechanism, you may be able to re-use that - mine was worn out - the reason the vac was discarded.<br /></p><p>Four little dowel sticks locate the lid on the bucket. You could slit open some rubber/foam tubing for a better seal around the bucket edge, but in my prototype, the smooth MDF board simply pressed against the top of the edge of the PVC bucket and it worked well enough. <i>If the motor can dent the bucket when the pipe is blocked with your hand, then it is sufficiently sealed</i>. If it collapses the bucket, then you need to drill a little 3 to 5 mm hole somewhere to let off some steam! </p><p>A bottom MDF board with four castor wheels, rounds out the project.</p><h3 style="text-align: left;"><b>Airflow and Vortex Voodoo </b><br /></h3><p><i>A vacuum cleaner really works with air flow, not vacuum. When high speed air from the hose enters the large diameter bucket, it acts like an expansion chamber and the air flow slows down dramatically, causing any dirt to fall to the bottom, but be sure to extend the inlet pipe to below the filter, else the dirt will clog the filter in no time. You can keep vacuuming up debris till the bucket is almost half full.</i><br /></p><p>There are lots of vortex voodoo videos on Yootoob about making your own shop vacuum cleaner in the most complicated way imaginable. This however, is for those who like to keep it simple: <i>Just mount everything on the lid of a bucket and be done with it.</i> For the ultimate lazy, almost never need emptying shop vac, you could mount the compressor on the lid of a 120 litre wheelie garbage bin, but I wanted it a little smaller!<br /></p><p>I still want to put a case around the motor, to dampen the noise and maybe use it as a leaf blower, but then I need a removable pipe. I also need to fashion a better hold down than the two bungee cords, but this prototype setup works a treat already. </p><p><i>This kind of kludge could be plugged into the blow hole of a woodworking saw or sander, but it would not be able to handle a large </i><a href="https://www.hornbach.sk/shop/Hoblovacka-HP200-s-prietahom/7715585/artikel.html"><i>hobłovačka</i> </a>(a wood thickness planer for the Slavik impaired). A planer makes a mind boggling amount of wood chips and requires a very large 4 inch pipe vac which will cost a king's ransom. With my Güde 405 planer, I don't use the dust funnel at all, jammed an Ikea pencil into the safety switch (<i>Whenever I go to Ikea I collect a few pencils - they are very useful for dowel rods and could even be used for writing too!</i>) and taped a large bag to the output side of the machine, so that most of the chips will fall into the bag - then I use an old broom and my bucket vac to clean up the rest of the mess when I'm done.</p><h3 style="text-align: left;"><b>Long Distance Tubing </b><br /></h3><p>If you have a few bucks to burn, get 10 meters of 50 mm diameter '<i>garden</i> <i>pond suction pipe</i>' (it is corrugated on the outside and smooth on the inside, for good air flow) and use that for your vacuum cleaner. Then you can put the banshee screamer outside the door of the shop, to save your ears from the whining noise (and annoy the neighbours instead).<br /></p><p>Every hand tool seems to have a different size blow hole, from 21 mm to 32 mm or thereabouts. One can get conical adaptors on Amazon, to cut to size for a ridiculous amount of money, or simply use a few turns of masking tape to fasten the vacuum nozzle to a circular saw, jigsaw, or hand planer. This makes it somewhat annoying when changing tools, but the conical widgets tend to fall out, requiring some tape anyway.</p><p>It is possible to make dust port adaptors from water bottles: Cut and shrink a bottle with a heat gun until it fits. That needs some practice, but costs nothing.<br /></p><p>Some tools do not have a blow hole at all - for example a drill or a 1/4 sheet orbital sander. I simply tape the snozzle of the vacuum pipe to the side of the machine and most of the dust then disappears into its maw.</p><p>It is amazing how much more pleasant it is to do woodwork when most of the dust is removed and you can actually breathe and see what you are doing!<br /></p><p>La voila!</p><p>Herman<br /></p>Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com0tag:blogger.com,1999:blog-1589959253862674712.post-2295289392172852392021-03-23T10:34:00.012+01:002021-10-20T16:17:02.629+02:00Knights Of The Round Table<div style="text-align: left;">I did my good deed for the week and rescued an old round/oval table.</div><p style="text-align: left;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjwV3XfWN9TkwTOMurlbqTbT9eo3ihvKgA7d3dwpvHfojkICw2gs9rsPyVts1sdR9QexQVDYijs35hnvfuK6FLEd6LTFBXa83kLtV8THV8-U5vRfpauFCOjM1JmpKg_u6iHsqT0EjaCsQs/s2016/RoundTable.jpg" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="2016" data-original-width="1512" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjwV3XfWN9TkwTOMurlbqTbT9eo3ihvKgA7d3dwpvHfojkICw2gs9rsPyVts1sdR9QexQVDYijs35hnvfuK6FLEd6LTFBXa83kLtV8THV8-U5vRfpauFCOjM1JmpKg_u6iHsqT0EjaCsQs/s320/RoundTable.jpg" /></a></div>These tables all suffer from the same design flaw, since the factories copy each other and they don't care about it lasting much beyond the show room door.<p style="text-align: left;"></p><p style="text-align: left;"> A table with a central leg will only last if it is made from steel. A wooden table that is light enough that normal human beings can still lift it, will eventually split, due to the enormous leverage from the table edge onto the central leg. <br /></p><p style="text-align: left;">The central leg is made from four planks glued together and then turned on a lathe - which also weakens it. The four feet, are invisibly bolted through into the hollow.</p><p style="text-align: left;"><i>When a knight in heavy armour leans on the table, the central leg tends to split at the bottom or top. </i><br /></p><p style="text-align: left;">I wedged the spars open and poured in some white glue and let it run down, while spreading it with a little swizzle stick and wiping up with a damp cloth. Then I clamped it and drilled four holes for dowel rods (the little white points above the clamp jaws in the picture) - while trying to miss the hidden bolts.</p><p style="text-align: left;">To put an 8 mm dowel into hard wood, requires an 8.1 mm hole if you want to be able to tap it in without splintering the dowel in the process, but where to find such a drill bit? Not all drill bits are made equal. I have multiple 8 mm bits and one of them, is ever so slightly bigger than the others, so it performs dowel duty. With MDF, it is not a problem - you can mash an 8 mm dowel into a 5 mm hole if you have to...<br /></p><p style="text-align: left;"></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjpXknb-ko4OB4NcEB2yttyww1Lys4WT8AheFAUZyRoCOXBLqnH-4w2_ueC2qmhuqw_qkTm0dRBU2AOrUNFQeShyphenhyphen8QagVNvOCGGwiqLBt3WgxlrPHc-eQ_MOiSo6zRtvXXmevrxrnGgC8Q/s1863/dowels.jpg" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1016" data-original-width="1863" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjpXknb-ko4OB4NcEB2yttyww1Lys4WT8AheFAUZyRoCOXBLqnH-4w2_ueC2qmhuqw_qkTm0dRBU2AOrUNFQeShyphenhyphen8QagVNvOCGGwiqLBt3WgxlrPHc-eQ_MOiSo6zRtvXXmevrxrnGgC8Q/s320/dowels.jpg" width="320" /></a></div>There is not much point in putting too many dowels, since next time a heavyset knight leans on the table, it will break somewhere else!<p style="text-align: left;">In a couple days, I'll grind the dowel heads down with a Dremel cutting wheel. <br /></p><p style="text-align: center;">-oOo-</p><p style="text-align: left;">Many/most woodworkers use far too much metal in their projects: <i>Hinges, locks, catches, slides, corner brackets, screws and nails...</i> </p><p style="text-align: left;">These widgets are very expensive and in most cases not necessary. One can make everything just with wood and glue, even hinges and locks. You can start by eliminating screws and nails by using wooden pins. The cost of your projects will reduce dramatically when you avoid using steel and brass fittings and the resulting projects will look rather nicer/olde fashioned/rustic.<br /></p><p style="text-align: left;"><b><i>A simple assembly trick is to glue and
screw a thing together, then remove the screws one at a time, enlarge
the hole and tap in a dowel with glue and a rubber mallet. With an electric
screwdriver and drill, this is super quick.</i></b><br /></p><p style="text-align: left;">I found that the best way to make dowel pins is to buy ready made ones!
Alternatively, cut 9 mm oak strips with a jigsaw from a scrap block (about 3 inches long works for me),
round them a bit with a knife, then hammer them through an 8 mm hole in
a steel plate. I use an old rafter joint bracket which has multiple
holes already, clamped in a vice. A humble washer mounted on a backing block will also work.<br /></p><p style="text-align: left;">There are many videos on Yootoob showing how people make dowels using
a drill and various kinds of cutting widgets. In my experience, this
only works with very thick dowels, at least 10 mm diameter. Thin stock
tends to shatter. Simply turning a dowel in the serrated jaws of a vice works very well, since one can adjust the vice until the dowel is
the right size.</p><p style="text-align: left;">Hammering a square peg through a round hole even works when there is a little knot in the peg. You just get a
bent dowel, as the one in the bottom right of the picture, while with a
drill lathe turning method, it will shatter at the knot. </p><p style="text-align: left;"><i>You don't have to sand a dowel smooth</i> - you are going to hammer it into a hole with glue - the roughness will help to fasten it. I cut and hammer a double handful of pegs and then I can put a project together without nails, screws or weird brackets.</p><div style="text-align: center;">-oOo- <br /></div><div><p style="text-align: left;"><i>One way to prevent repeated breakage of a round table, is to loosen the table top (back some screws out a quarter inch), so that it is balanced precariously and if anyone would lean on the table, then it will wobble threateningly and teach them not to, by spilling their hot coffee into their laps, but this particular extendable table design unfortunately doesn't lend itself to such an evil solution.</i></p><p style="text-align: left;"> </p><p style="text-align: left;">La voila!</p><p style="text-align: left;">Herman<br /></p></div>Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com0tag:blogger.com,1999:blog-1589959253862674712.post-86766066339601490742021-03-13T08:43:00.006+01:002022-08-20T20:38:57.921+02:00The Office<h3 style="text-align: left;">The Office</h3><div style="-webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-decoration: none; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px;"><span style="color: #444444;"><span>Do you still remember what an<span class="Apple-converted-space"> </span><i>Office</i><span class="Apple-converted-space"> </span>is? Those large multistorey buildings where we all used to<span class="Apple-converted-space"> <i>fearlessly </i></span><i>share</i><span class="Apple-converted-space"> </span>our cold and flu viruses like a<span class="Apple-converted-space"> </span><i>big happy family</i>?</span></span></div><div style="-webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-decoration: none; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px;"><span style="color: #444444;"><span><br /></span></span></div><div style="-webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-decoration: none; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px;"><span style="color: #444444;"><span><i>The Book</i><span class="Apple-converted-space"> </span>on a lectern where you sign in/out, with<span class="Apple-converted-space"> </span><i>The Witch</i><span class="Apple-converted-space"> </span>glaring at you for being<span class="Apple-converted-space"> </span><i>ten seconds</i><span class="Apple-converted-space"> </span>late, whether your nails are clean and your shirt tucked in. The front desks that are slightly bigger, with a better quality desk lamp and which may even have a<span class="Apple-converted-space"> </span><i>carpet</i>! The CARDEX cards along the wall, the clattering Telex machine at the back...</span></span></div><div style="-webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-decoration: none; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px;"><span style="color: #444444;"><span> </span></span></div><div style="-webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-decoration: none; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px;"><div class="separator" style="clear: both; text-align: center;"><span style="color: #cccccc;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjGAFQMsG6meKUR7TraHfo7cyt_sRdi9Z789Ff_chiA_OfhkSRgojx-HXGrRDGVk18wvLXhRDw4lumOh2chY5zc8_RaMGdSMreTf2kVCqhlPBzJp0kSqL_VIoYHWr_o3c1KhXq0_L1t_UA/s1622/TheOffice.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="792" data-original-width="1622" height="312" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjGAFQMsG6meKUR7TraHfo7cyt_sRdi9Z789Ff_chiA_OfhkSRgojx-HXGrRDGVk18wvLXhRDw4lumOh2chY5zc8_RaMGdSMreTf2kVCqhlPBzJp0kSqL_VIoYHWr_o3c1KhXq0_L1t_UA/w640-h312/TheOffice.png" width="640" /></a></span></div></div><div style="-moz-text-size-adjust: auto; -webkit-text-stroke-width: 0px; caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: center; text-decoration: none; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;"><span style="color: #cccccc;"> <b>Mid 20th Century Office</b><br /></span></div><div style="-webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-decoration: none; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px;"><span style="color: #cccccc;"><br /></span></div><p><span style="color: #444444;"><span><span style="-webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; caret-color: rgb(0, 0, 0); display: inline; float: none; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-decoration: none; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px;">It is interesting to note how the desks get gradually more messed up towards the rear of the room. That is always where the</span><i style="-webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-decoration: none; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px;"><span class="Apple-converted-space"> </span>real work<span class="Apple-converted-space"> </span></i><span style="-webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; caret-color: rgb(0, 0, 0); display: inline; float: none; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-decoration: none; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px;">gets done.</span></span></span></p><p><span style="color: #444444;"><span><span style="-webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; caret-color: rgb(0, 0, 0); display: inline; float: none; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-decoration: none; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px;">Have fun!</span></span></span></p><p><span style="-webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; caret-color: rgb(0, 0, 0); color: black; display: inline; float: none; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-decoration: none; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px;"><span style="color: #444444;"><span>Herman </span></span><br /></span></p>Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com0tag:blogger.com,1999:blog-1589959253862674712.post-40321912548273127052021-01-18T00:33:00.014+01:002021-02-26T12:24:03.930+01:00UAV Communications And Mission Systems<p>Tactical Unmanned Air Vehicles present an interesting communications challenge. Flying an RC toy in your back yard is fun, but controlling a heavy aircraft, hundreds of kilometers away over the desert, is something else entirely. Abu Dhabi IDEX 2021 walk through: <a href="https://youtu.be/PkNzGEeBOBo">https://youtu.be/PkNzGEeBOBo</a></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjNfQEsuXL4ZtIVLCTi8YdVNGonNMyK55c9X26bMu4pI1uhiSl1KHVnnXDxL8MresVIMsTLfaUnnPrOYXSqRfr3gPIQOgJKikZklEj9XQ8qzftj5mou44naCOCEzQT06WqVBwqon3GQuPg/s1280/garmoosha-idex.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="576" data-original-width="1280" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjNfQEsuXL4ZtIVLCTi8YdVNGonNMyK55c9X26bMu4pI1uhiSl1KHVnnXDxL8MresVIMsTLfaUnnPrOYXSqRfr3gPIQOgJKikZklEj9XQ8qzftj5mou44naCOCEzQT06WqVBwqon3GQuPg/w400-h180/garmoosha-idex.jpg" width="400" /></a></div><p></p><p style="text-align: center;"><b>ADASI 500 kg Unmanned Helicopter ready for IDEX 2021</b><br /></p><p>The below book is still a draft and it is published here as a series of PNG files - one per page. The below should be viewable in any browser. If you wish to get a PDF file, send a message to <i>herman at aeronetworks dot ca</i> and then we can agree on which FTP service to use.</p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgCKw0n-b42s1Tb6vPU8ES5TBGkfSq3W_Xf5vmToAKA9zxSOHFpV7Rz8_RuSseBgGTjFt_rFjsHpLdHoNyQWLKiMsAfupv4X8yYljTBblrfkUNjExePyYfpVVxn8vEBqcHTquJPPgfSkkc/s2048/uav00.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1583" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgCKw0n-b42s1Tb6vPU8ES5TBGkfSq3W_Xf5vmToAKA9zxSOHFpV7Rz8_RuSseBgGTjFt_rFjsHpLdHoNyQWLKiMsAfupv4X8yYljTBblrfkUNjExePyYfpVVxn8vEBqcHTquJPPgfSkkc/w494-h640/uav00.png" width="494" /></a></div><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhwTbAi_YDCwscZWLXGdPxZlzCfz7MER1QHmr8KweH8Zg0H7w7B6GfPp9OJbRCJdDFU6VARJzuFp8VBh0bgyrXZ5CfuiVMMEXBTKnaMaHzPHdc9Bm12kjCqosZTzHhBAQUxDcYEqxckuGI/s2048/uav01.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1583" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhwTbAi_YDCwscZWLXGdPxZlzCfz7MER1QHmr8KweH8Zg0H7w7B6GfPp9OJbRCJdDFU6VARJzuFp8VBh0bgyrXZ5CfuiVMMEXBTKnaMaHzPHdc9Bm12kjCqosZTzHhBAQUxDcYEqxckuGI/w494-h640/uav01.png" width="494" /></a></div><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEicPdC4pm-4zrBfEsM0dFzGnyS5bU-O0fwJehSaBvlI8ndca5QsUSoU_virRlWWHH6VPXhIg3JaN0hDcWqOwdf_yAwzzZHeP0ZF_Qbiq8XIzCoHyIX19Y0Tuq1APWSvkrj7gSwVitZ-6z8/s2048/uav02.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1583" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEicPdC4pm-4zrBfEsM0dFzGnyS5bU-O0fwJehSaBvlI8ndca5QsUSoU_virRlWWHH6VPXhIg3JaN0hDcWqOwdf_yAwzzZHeP0ZF_Qbiq8XIzCoHyIX19Y0Tuq1APWSvkrj7gSwVitZ-6z8/w494-h640/uav02.png" width="494" /></a></div><br /><div class="separator" style="clear: both; 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text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjT3FX3pfphneMB0hpzbpw7jJIkxR_67XjFZy2EfRoFnSqAp1Xu8XytpMvpRG1WAO54RaegxYS2bkKVFGdqcKOO_FlKMm8gDgAr0gyT4uIKf43SSZObyIZtUHCgw7eal6Kv_B9oev5cNus/s2048/uav83.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1583" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjT3FX3pfphneMB0hpzbpw7jJIkxR_67XjFZy2EfRoFnSqAp1Xu8XytpMvpRG1WAO54RaegxYS2bkKVFGdqcKOO_FlKMm8gDgAr0gyT4uIKf43SSZObyIZtUHCgw7eal6Kv_B9oev5cNus/w494-h640/uav83.png" width="494" /></a></div><p></p><p>Enjoy!</p><p>Herman<br /></p><p></p>Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com0tag:blogger.com,1999:blog-1589959253862674712.post-14408937415551954112020-10-06T20:50:00.070+02:002021-10-20T16:37:10.520+02:00Olde Fashioned Clay Shooting<p>After several years wandering in the Arabian desert, we are heading home to Canada, via Europe. Thanks to Covid19 we cannot travel as easily as we want now, but with the shift in location, my hobbies can shift to something more green and less dusty (!?). At long last, my Slovak permanent resident visa application is in progress with the Foreigner Police.<br /></p><p>Since I'm an ex-army officer, I sometimes enjoy making a big noise with guns and other toys and have the bad hearing and tinnitus to show for it. </p><p>The tinnitus is thanks to <a href="https://en.wikipedia.org/wiki/Oerlikon_GDF">Oerlikon Contraves 35 mm AA guns</a> and radars - very noisy things with a high firing rate and lots of fun on a large gun range. Three double barrel guns, firing at an airborne target at hundreds of rounds per second, is the ultimate in skeet shooting. I was workshop officer of a maintenance facility for a while and since then I worked with helicopters... Ear muffs are for sissies right? RIGHT!? - A bit too late now...<br /></p><p style="text-align: center;"><i>The road less traveled may be more fun and </i></p><p style="text-align: center;"><i>you may learn something new.</i><br /></p><p>An interesting quirk in the firearms regulations of most countries, is that blackpowder muzzle loading guns and rifles are considered antiques (no matter how old, or new they are) and are not as strictly controlled as modern firearms, which make them much less of a legal hassle for someone who is traveling around the globe. </p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUvRgsUfa302mkaPpdxuToq84o5rCEkCi3Eu8ybYegcilELn3qt9kaFTd9INgk0uazKzC_yittdbdsySRnHKDUY4h_ow_Sgc2AyZKbb9YA5ohHJ0Y-qlX8zjGIiESE3ffsMhS9PRL2DGE/s794/Screen+Shot+2020-10-15+at+10.15.55+AM.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="272" data-original-width="794" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUvRgsUfa302mkaPpdxuToq84o5rCEkCi3Eu8ybYegcilELn3qt9kaFTd9INgk0uazKzC_yittdbdsySRnHKDUY4h_ow_Sgc2AyZKbb9YA5ohHJ0Y-qlX8zjGIiESE3ffsMhS9PRL2DGE/s320/Screen+Shot+2020-10-15+at+10.15.55+AM.png" width="320" /></a></div><br />Therefore, almost anyone can go and buy a <i>perkusni zbrane</i>, get some blackpowder, lead balls and patches and go try to make holes in paper targets, without the need to complete reams of paperwork. The hardware and ammo also costs a fraction as much as modern arms. <i>This makes it a viable hobby, of the kind where you buy all the costly kit, play with it for a year or three and then move on to the next fad...</i><br /><p></p><p>When I was about 12 years old, I made my own blackpowder, crackers and rockets - in the good old bad old days, one could simply buy the ingredients at a chemist - who wagged his finger at me. I
stopped when, after a couple years of experimenting, the little paper
tape rockets became too good for my own good. A big one went straight up: WHOOSH! ... it just disappeared in a blinding flash-bang - I did not see it fly at all - and then it came down right next to me: THUNK!!! ... and that was the last one. It sure taught me to appreciate O'l Isaac Newton and what tends to happen immediately after something went up. </p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiX35SKrepC4WhJ5oKpihfLr25Y7my6W-c6Fgh1SQR1Ye7RinRzFM7dRNBPDcPtoRBB2ftuO3kL4v99kQJCtER-wyjEcIVwrWbMf8Z5mSSCi7j5NzBWrVvN94kVuARAwkmwovdvuLjN3PE/s676/Screen+Shot+2020-10-15+at+12.05.38+PM.png" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="676" data-original-width="450" height="191" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiX35SKrepC4WhJ5oKpihfLr25Y7my6W-c6Fgh1SQR1Ye7RinRzFM7dRNBPDcPtoRBB2ftuO3kL4v99kQJCtER-wyjEcIVwrWbMf8Z5mSSCi7j5NzBWrVvN94kVuARAwkmwovdvuLjN3PE/w127-h191/Screen+Shot+2020-10-15+at+12.05.38+PM.png" width="127" /></a></div><br /><p><br /></p><p>I really can't recommend grinding your own powder, but it certainly is possible if you are fool hardy like I was as a kid - at least I was smart enough to use a small brass pestle, so I still have all my fingers. In the middle ages, that is what the gunsmiths and alchemists in the castles did - they probably also occasionally caused the <i>unscheduled rapid enlargement</i> of the odd dungeon in the process. I guess I should have been born a few hundred years earlier. Today, it is better to buy consistent quality FFG powder at a gun store though!<br /></p><p>Here is the Blackpowder Book: <a href="http://www.blackpowderbook.com">http://www.blackpowderbook.com</a> <br /></p><p>The reason behind the seeming lack of control is obvious: <i>"Hey mate, hold my powder horn and ram rod, then gimme your wallet!"</i> just ain't gonna work very well, as the mugger likely will have a ramrod up his nose or twisted around his neck.</p><p><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjDedn0Yu4LqyjY7eJKWv982vQciJwfxDb5St27VyxEiKjY2G0rdGqx6NHsm6w98K9SwOYSom3mNQiE8D86s2N1plunzrmrGjueS4InF3RlyfbyATWt9golKxPbDEWVYJi5d9t1we6ANSo/s615/274K.310.jpg" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="245" data-original-width="615" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjDedn0Yu4LqyjY7eJKWv982vQciJwfxDb5St27VyxEiKjY2G0rdGqx6NHsm6w98K9SwOYSom3mNQiE8D86s2N1plunzrmrGjueS4InF3RlyfbyATWt9golKxPbDEWVYJi5d9t1we6ANSo/s320/274K.310.jpg" width="320" /></a>There are kit blackpowder guns for those who like to do woodwork that can go boom: <a href="https://www.davide-pedersoli.com/tipologia-prodotti.asp/l_en/idt_68/rifles-muzzleloading-kit-rifles.html">https://www.davide-pedersoli.com/tipologia-prodotti.asp/l_en/idt_68/rifles-muzzleloading-kit-rifles.html</a></p><p> </p><p><i>BTW, in my experience it is easier to disarm a mugger with a gun,
than to disarm a mugger with a knife. If you want to know how, go do
some self defense classes. Knowing how to effectively defend yourself
and apply first aid (to the wannabe mugger) are essential skills that everyone should have, but simply running away is also a pretty good defense, since even a mugger won't shoot someone in the back - it goes against human nature.</i></p><p>When I was young and handsome, I usually carried a huge stainless steel diver's knife with me and actually pulled it twice to ward off an aspiring mugger, who then was very surprised that mine was way bigger than his and ran off (<i>This is known as the Crocodile Dundee Effect</i>). Now that I am only handsome, a compact muzzle loading pistol would be more appropriate for self defence. <br /></p><p>The thing to bear in mind is that if you can disarm someone so easily, then you can be disarmed just as easily. So when you find yourself in a bad situation, you need to react fast and decisively and that requires training. <br /></p><div style="text-align: center;"><i>A muzzle loader usually gives you only one shot. </i></div><div style="text-align: center;"><i>If you want two shots, get another gun.</i> </div><p>The so called Dueling Pistols were not really for dueling - they were for having a second shot at an oncoming bear or tiger. <i>Tough and aggressive meat eating animals like human beings, bears and tigers are seldom stopped by a single shot</i> and the kinetic energy calculations at the bottom of this article shows why.<br /></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg3BEJ8u7YLC80jRubG8JMOHaDLhgCO6CJsmehjiHf4vRT74TtYOkoOlU3IjWWawKug48Iox6O9V9rX8k9KGNK7fOyOAragQIPRzyiDMxpX0Oy_Ibxne8RpKDdWSRR1bG72UTAyNZ96LXw/s790/Screen+Shot+2020-10-06+at+10.04.57+PM.png" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="572" data-original-width="790" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg3BEJ8u7YLC80jRubG8JMOHaDLhgCO6CJsmehjiHf4vRT74TtYOkoOlU3IjWWawKug48Iox6O9V9rX8k9KGNK7fOyOAragQIPRzyiDMxpX0Oy_Ibxne8RpKDdWSRR1bG72UTAyNZ96LXw/s320/Screen+Shot+2020-10-06+at+10.04.57+PM.png" width="320" /></a></div><br /><p>Here is a modern looking Czech made Detonics blackpowder double barrel pistol: <a href="https://www.kentaurzbrane.cz/czechgun-gladiator-cal--500-hd-d2-professional/">https://www.kentaurzbrane.cz/czechgun-gladiator-cal--500-hd-d2-professional/</a> </p><p></p><p>It really doesn't look like a muzzle loader at all. The trigger cycles between the two barrels, for double the fun. <br /></p><p>I really don't want to be on the wrong end of this beauty and stare down those two half inch bores - you can stick your thumbs into them. <i>(I hope that if a mugger has a gun, that he will notice that my half inch barrels are way bigger than his and run off!)</i></p><p>This 0.50" calibre gun is about as powerful as a modern 9 mm pistol, so it packs a good punch and you can load it with bird shot. <i>With a scatter shot, you are far less likely to miss completely when you are under pressure.</i> With a close up mugger, the blackpowder flames will cauterize his wounds...<br /></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgdymoCIbBtfz_sggxxtiCTAbo6qlKj9-hYurGKGTxMGEtYJFCeT6ObZSmd5M7CvCCNP3viyKsttcS63M_eYdSAPn_NuKrykShUEc6v2tPEcbnFDUNx-VsgJJqgGSJOUE5K5P0eYhyphenhyphen6qXc/s400/Screen+Shot+2020-10-15+at+9.49.31+AM.png" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="400" data-original-width="302" height="140" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgdymoCIbBtfz_sggxxtiCTAbo6qlKj9-hYurGKGTxMGEtYJFCeT6ObZSmd5M7CvCCNP3viyKsttcS63M_eYdSAPn_NuKrykShUEc6v2tPEcbnFDUNx-VsgJJqgGSJOUE5K5P0eYhyphenhyphen6qXc/w106-h140/Screen+Shot+2020-10-15+at+9.49.31+AM.png" width="106" /></a></div><br />If you want to use a muzzle loader for self protection and don't want to reload it once a week, then you need to seal the barrel with a little bit of beeswax and also seal the percussion cap with wax or nail polish, to keep humidity out of the powder. If the charge is sealed in the barrel, then it should provide a reliable shot when called upon, just like a metal cartridge. This is also a good idea when hunting in a wet forest. Obviously you don't need to do this when you are only punching expensive little holes in paper targets.<p></p><p>Blackpowder burns relatively slowly - therefore a blackpowder gun needs to have a long barrel to reach maximum acceleration of the ball. Old handguns had 9 inch (or longer) barrels. Even Rambo cannot stuff one of those in his vest pocket. The shortest barrel that packs a meaningful punch is about 6 inches, which is still quite big. The gun size, heft, deep throated subsonic boom, smoke, fire and brimstone (OK, maybe not brimstone...) all contributes to a very fun day at the gun range. Oh, a simple tip: <i>Don't wear a white shirt when you go blackpowder blasting...</i><br /></p><p>For indoor smoke free target shooting, you can get special propellant caps with a larger nipple and plastic bullets (no powder required). Then you can have fun in your basement or garage - until the neighbours complain about the noise.</p><p>For self defense, I recommend loading your smoke blaster with bird shot. Over short range, it is equally devastating as a ball, the chances of completely missing the mugger is reduced, while the danger to innocent bystanders and your neighbours in the next house, is very much reduced.<br /></p><p>When you go hunting, you only get one shot, since after that shot, everything that can, runs & flies away and whatever stays put, is probably not edible and about to succumb of natural causes. So hunting with a military style rifle, a bandolier full of cartridges and seven loaded magazines like Rambo, is just for show. Since you are probably not O'l Sylvester, all that extra ammo will just wear you down and is quite useless.</p><p style="text-align: center;"><i>Where there is smoke,</i></p><p style="text-align: center;"><i>There is a <strike>fire</strike> blackpowder gun.</i><br /></p><p>In practice, a dedicated hunter seldom manages to bag a deer, maybe once or twice in a decade, but they will never admit to it. This is the same as an angler who has lots of stories about the ones that got away and seldom brings a fish home. Same as angling, hunting is mostly done sitting down on a little wire and canvas stool and waiting, hoping for a deer with a stuffy nose that cannot smell you, to come your way before you are too cold and stiff to pick up your rifle and they seldom do.<br /></p><p>So, most actual 'hunting' is done in your garage, cleaning the gun, tweaking the sights, molding bullets and reloading cartridges with great precision, only to go and blast them away on a shooting range at paper or clay targets. <i>Any Bambis, pheasants or ducks are usually quite safe. (The paper targets and skeets are frequently quite safe as well...)</i><br /></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgyUGkBtPwYlabwjiel1fL29BYK7azOw5tCOV6WJVJ9O9bGA4P9Z7nprpU_GAsFHWyaFknIrPvmbG0twNMzGqYZPLwZdWOwbDrcNRF81lQPCv4RWhJKeigtCf1041FpqLJUIGklCzTipto/s688/Screen+Shot+2020-10-06+at+9.52.52+PM.png" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="316" data-original-width="688" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgyUGkBtPwYlabwjiel1fL29BYK7azOw5tCOV6WJVJ9O9bGA4P9Z7nprpU_GAsFHWyaFknIrPvmbG0twNMzGqYZPLwZdWOwbDrcNRF81lQPCv4RWhJKeigtCf1041FpqLJUIGklCzTipto/s320/Screen+Shot+2020-10-06+at+9.52.52+PM.png" width="320" /></a></div><br />Since I am not your average army muscle, but rather more of a Gadget Geek, a laser boresight calibration tool is indispensable to me and it saves a whole lot of reloading and calibration shooting to get on target: <a href="https://sightmark.com/products/337/sightmark-triple-duty-universal-green-laser-boresight/">https://sightmark.com/products/337/sightmark-triple-duty-universal-green-laser-boresight/</a><br /><p></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjG9obzKkIgL2MyYk8IX7vzXKnPi6IFBKHfe58Z3gWCGU71bOhqePj8yzbyga_L5MqqO9xZfYwn7lkQzAl68IAWsSJfJF13B5DhbfxXAlhGyNSd4aXLChbDKVVxzOGqyMnkNpBdROXAMOM/s1054/Screen+Shot+2020-10-06+at+10.00.12+PM.png" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="700" data-original-width="1054" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjG9obzKkIgL2MyYk8IX7vzXKnPi6IFBKHfe58Z3gWCGU71bOhqePj8yzbyga_L5MqqO9xZfYwn7lkQzAl68IAWsSJfJF13B5DhbfxXAlhGyNSd4aXLChbDKVVxzOGqyMnkNpBdROXAMOM/s320/Screen+Shot+2020-10-06+at+10.00.12+PM.png" width="320" /></a></div><br />Similarly, my guns do not have metal sights, but are fitted with red dot reflex prism sights, which is the kind of thing my great grampaw would have given his last haypenny for: <a href="https://www.opticsplanet.com/truglo-red-dot-micro-tru-tec-3-moa-dot-picatinny-pistol-blk.html">https://www.opticsplanet.com/truglo-red-dot-micro-tru-tec-3-moa-dot-picatinny-pistol-blk.html</a><br /><p></p><p>With a red dot sight, you keep both eyes open and put the dot on the target. That is all. The bullet will then magically convert the red dot into a black hole. The effect is similar to a scope, but the dot is very much easier to see than cross hairs, since the projection appears in the same focal plane as the target, which seems to be more important the older you get. I am pretty useless with an old fashioned metal sight and with a red dot, I can actually occasionally hit something. (<i>I'm a Signaler, and Sparkies don't get to practise shooting much in the army!</i>).<br /></p><p>These skeleton prism sights are so small that they can be fitted on a pistol also and then you can ask the mugger <i>where</i> <i>exactly</i> does he want the shot to go... if he wasn't sensible enough to run away already.<br /></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhu-HyKEJzUH9ae7YEutbkQSpnZL1pLJMeTnJ_jchoM9WtTqKkPkLpL5yQgh1PdD8nnwijhTXAZH_2vy_MAoAF05PKSEmTQ1cFxXeMajHYlR_Y0eWDK1vsCU8STvha7YTrogGsYUNPnqfc/s1538/Screen+Shot+2020-10-06+at+10.40.50+PM.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1210" data-original-width="1538" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhu-HyKEJzUH9ae7YEutbkQSpnZL1pLJMeTnJ_jchoM9WtTqKkPkLpL5yQgh1PdD8nnwijhTXAZH_2vy_MAoAF05PKSEmTQ1cFxXeMajHYlR_Y0eWDK1vsCU8STvha7YTrogGsYUNPnqfc/s320/Screen+Shot+2020-10-06+at+10.40.50+PM.png" width="320" /></a></div><br />For moving targets, a clay thrower is a ton of fun: <a href="https://www.basspro.com/shop/en/champion-traps-highfly-string-release-trap">https://www.basspro.com/shop/en/champion-traps-highfly-string-release-trap</a> and there are no shortage of places to go and practise, without joining a club, since contrary to what the Doomers are saying, Europe and North America are actually reforesting/rewilding: <a href="https://ec.europa.eu/jrc/en/publication/eur-scientific-and-technical-research-reports/agricultural-land-abandonment-eu-within-2015-2030">https://ec.europa.eu/jrc/en/publication/eur-scientific-and-technical-research-reports/agricultural-land-abandonment-eu-within-2015-2030</a><br /><p></p><p>A problem with shooting clays with blackpowder, is that you cannot always see whether you hit the clay, due to the smoke. (<i>Actually, you just need to step to the side, to get out of a lingering puff of smoke. It feels like the whole world disappears in the murk, but it is really just in front of your head</i>). Whether you hit the clay or not though, it is the same amount of fun! </p><p>The best tip I can give a new trap shooter, is to <i>aim under the clay</i>. Your first instinct is to aim high, since the clay is flying up at first - don't do that - what goes up, will come down. If you are lucky, you may then actually hit one or two. If you are just starting, consider shooting at a few tethered helium party balloons first, to get the basics for how to comfortably shoulder a shot gun and aim into the air. You'll be surprised how difficult it is to actually hit a balloon waving in the breeze. It can be a very humbling experience.<br /></p><p>I would love to build a super efficient clay tosser, but they are so cheap, it is really not worth the effort. Even a second hand thrower on Ebay, tends to cost more than a new one at a gun shop.</p><p> </p><p><b>Kinetic Energy of Ball Ammunition</b></p><p>Here are some example numbers for the fellow Gunsmoke Geeks out there.</p><p style="text-align: center;"><i>If something is worth doing at all, then it is worth overdoing. </i></p><p>Therefore my favourite is a 1/2 inch bore. I don't care much for peashooters!<br /></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjjew3GQmtfST39XW53CTlYQukcgzww2Sj8u96DisbMlJWz8fZh5nyWQHIi9tzZv7tb9ryvkBpW-ibT8ZBLVb0gyxPO8sTE3Xp4qz-R9VhRiFN7z-YC0eJmCe-dhpxIYZo0oJYJTTA4BF4/s908/Screen+Shot+2020-10-15+at+11.40.28+AM.png" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="546" data-original-width="908" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjjew3GQmtfST39XW53CTlYQukcgzww2Sj8u96DisbMlJWz8fZh5nyWQHIi9tzZv7tb9ryvkBpW-ibT8ZBLVb0gyxPO8sTE3Xp4qz-R9VhRiFN7z-YC0eJmCe-dhpxIYZo0oJYJTTA4BF4/s320/Screen+Shot+2020-10-15+at+11.40.28+AM.png" width="320" /></a></div><br /><p></p><p></p><p></p><p>Conversions:<br /></p><ul style="text-align: left;"><li>7000 grain = 1 lb</li><li>2.2 lb = 1 kg</li><li>15.4 grain = 1 g</li><li>1 fps = 0.305 m/s</li><li>Cricket ball = 163 g</li><li>A 0.50" calibre long gun can shoot a 250 grain (16.2 g) ball at 1000 fps (305 m/s)</li><li>An ultra fast Cosmic Ray particle = 8 Joule</li><li>Speed of sound = 343 m/s = 1125 fps</li></ul>Weight of a Round Lead Ball:<br /><ul style="text-align: left;"><li>Density of lead = 11,340 kg/m3 = 11.34 g/cm3 = 0.01134 g/mm3</li><li>Melting point = 600 K</li><li>0.50” calibre ball diameter = 0.49” = 12.446 mm (with a 5 mil cotton patch)<br /></li><li>Radius = 6.223 mm</li><li>Vol = 4/3 π r^3</li><li>Vol = 4/3 x π x 6.223^3 = 1009 mm3</li><li>Weight = 1009 x 0.01134 = 11.5 g </li><li>Weight = 11.5 x 15.4 = 177 grain</li></ul><p style="text-align: left;">A slug or conical bullet can be much heavier than a round ball, up to about 320 grain like the slug pictured above, but 250 grain is typical for 0.50 calibre.</p>A Cricket Ball batted for a six at 100 km/h:<ul style="text-align: left;"><li>100 km/h = 27.8 m/s <br /></li><li>E = 1/2 x mass x velocity^2</li><li>Ecb = 1/2 x 0.163 x 27.8^2 = 63 Joule</li><li>8 Cosmic Rays </li></ul><p>A 15th century long bow could shoot an arrow with an impact energy of
about 100 Joule, so lets see how balls and arrows compare to black powder guns. <br /></p>A Pistol fired 250 grain bullet traveling at 500 fps: <ul style="text-align: left;"><li>E500 = 1/2 x 0.0162 x 153^2 = 190 Joule</li><li>2 Arrows <br /></li><li>3 Cricket Balls</li><li>24 Cosmic Rays <br /></li></ul><p>A Long Gun fired 250 grain bullet traveling at 1000 fps:</p><ul style="text-align: left;"><li>E1000 = 1/2 x 0.0162 x 305^2 = 754 Joule</li><li>7 Arrows <br /></li><li>12 Cricket Balls</li><li>94 Cosmic Rays <br /></li></ul><p>Muzzle velocity is clearly much more important than the ball mass and a longer barrel therefore makes a big difference.<br /></p><p>Modern smokeless ammo could propel a bullet supersonic at more than double the speed of a blackpowder gun and could pack more than 4 times the energy, but instead what happens, is that modern guns and ammo are smaller, lighter and easier to handle, for the same punch - and - consequently not nearly as much fun as a huge, booming and smoking, pirate pistol!</p><p><br /></p><p></p><p></p><p></p><p></p><p></p><p></p><p><b>Muzzle Velocity</b></p><p>The totally Gadget Geek way to measure muzzle velocity is with a Doppler Radar: <a href="https://www.midwayusa.com/product/1016447132">https://www.midwayusa.com/product/1016447132</a><br /></p>A Labradar may blow your hobby budget though. <p>You can also measure the average muzzle velocity with a microphone and an oscilloscope, or a laptop computer with a sound recorder, shooting at a steel plate.</p><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi6MA9k65Nkg6K7TLj6HX19vLjTwwp4Qw1LwODXYob8Dg8nbNW_BIoiIT2LDroQ43ohdLLyChMV6zNgmXl7eC339-nPhH9OtdTt2UF7_XTPgWGk2TBqC9lFmn7lrl1yzWt1rwFvxcFsf-A/s1512/velocity.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1512" data-original-width="1512" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi6MA9k65Nkg6K7TLj6HX19vLjTwwp4Qw1LwODXYob8Dg8nbNW_BIoiIT2LDroQ43ohdLLyChMV6zNgmXl7eC339-nPhH9OtdTt2UF7_XTPgWGk2TBqC9lFmn7lrl1yzWt1rwFvxcFsf-A/s320/velocity.jpg" /></a></div><p style="text-align: center;"><b>Measure Bullet Velocity at the Speed of Sound </b><br /></p><p>For that to work well, you got to get up early and be the first one at the range. Note that if the microphone is placed halfway, or off to the side in an equilateral triangle, rather than next to the gun, then the exact speed of sound doesn't matter.</p><p>Here are a couple of other adventurous geeks with the same ideas: </p><p><a href="http://nitricacid.blogspot.com/2005/11/using-audacity-recording-software-to.html">http://nitricacid.blogspot.com/2005/11/using-audacity-recording-software-to.html</a></p><p><a href="http://www.inpharmix.com/jps/Jims_chrono.html">http://www.inpharmix.com/jps/Jims_chrono.html</a> </p><p>It could make a neat Raspberry Pi / Arduino project to calculate and display the <i>Boom-Clang Speed</i> instantly. Maybe now I finally have a better use for Nixie tubes than a clock...<br /></p><p><br /></p><div><p>Have fun!</p><p>Herman<br /></p><p><br /></p><p><br /></p><p><br /></p></div>Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com0tag:blogger.com,1999:blog-1589959253862674712.post-9414959716945734022020-09-30T15:51:00.004+02:002021-07-06T19:40:36.870+02:00Hosts File Junk Filter for a Mac<p><b>Take out the trash, don't bring it home.</b></p><p>There are always a small number of people who go out of their way to annoy everyone else. The result is that state parks, lakes and beaches have much in common with the internet: <i>There is a ton of trash everywhere you go.</i></p><p>You could install an advertisement blocker on your web browser, but those things are usually also spyware in their own way, just less so, than an unprotected network.</p><p>A Macintosh is a UNIX machine and it is actually very easy to block most trash on the internet. Download one of the big hosts files that enumerate most trash sites and save it as file <i>/etc/hosts</i></p><p>Here is a good one, provided by a kind soul: <a href="https://someonewhocares.org/hosts/zero/hosts">https://someonewhocares.org/hosts/zero/hosts</a></p><p>Instructions and explanations are in there if you are still a bit helpless about this.</p><p>It contains lists like this:</p><p><i><span style="font-family: courier; font-size: xx-small;">0.0.0.0 track.msadcenter.afgz.com</span></i></p><p><i><span style="font-family: courier; font-size: xx-small;">0.0.0.0 track.msadcenter.ajfy.com</span></i></p><p><i><span style="font-family: courier; font-size: xx-small;">0.0.0.0 track.msadcenter.ama.com</span></i></p><p><i><span style="font-family: courier; font-size: xx-small;">0.0.0.0 track.msadcenter.bfy.com</span></i></p><p><i><span style="font-family: courier; font-size: xx-small;">0.0.0.0 track.msadcenter.bvp.com</span></i></p><p><i><span style="font-family: courier; font-size: xx-small;">0.0.0.0 track.msadcenter.cdn.com</span></i></p><p><i><span style="font-family: courier; font-size: xx-small;">0.0.0.0 track.msadcenter.ceio.com</span></i></p><p><i><span style="font-family: courier; font-size: xx-small;">0.0.0.0 track.msadcenter.chpn.com</span></i></p><p><i><span style="font-family: courier; font-size: xx-small;">0.0.0.0 track.msadcenter.cxtv.com</span></i></p><p>The <i>0.0.0.0 is an unroutable address</i> and the domain name on the right is the offending party.</p><p><i>You could edit the file and remove a few # signs to activate some more blocks for Microsoft, Google and Double Click, which may affect the operation of some sites which you may never visit anyway and you can also add ones you discover by yourself.<br /></i></p><p>This works, because when the network stack does a <i>Domain Name Lookup</i>, it first looks inside the local <i>hosts</i> file. If the name is defined there and points to nothing, then the destination becomes unreachable. </p><p>Your internet connection will now work a whole lot faster also, since the requested garbage is simply not downloaded at all.</p><p>Simple as that.</p><p>Have fun!</p><p>Herman</p>Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com1tag:blogger.com,1999:blog-1589959253862674712.post-64529715666912786672020-08-21T13:25:00.022+02:002023-09-20T19:39:36.785+02:00RTL-SDR Weather Satellite Preamplifier<p>I have been playing with the <a href="https://satnogs.org">SATNOGS</a> earth observation satellite system for a few years, but since I am still living in the desert, the climate is against outdoor activities, so its been a bit low key. To work on an antenna on the roof, requires a hat, black sunglasses, a wet T-shirt, a wet towel, a litre of water and a big black umbrella and after that I'm broiled for the day...</p><p>The few times I tried to download a weather picture, it actually worked, despite having seemingly more noise than signal. An <a href="https://www.rtl-sdr.com">RTL-SDR</a> or <a href="https://greatscottgadgets.com">HackRF One</a> receiver really needs to have a low noise RF preamplifier for best results. There are several solid state, one transistor preamp kits available that one can buy and build in an evening and stick on the antenna cable, but <i>why do something the easy way, if one can do it the hard way?</i></p><p>I recently made a 'simple' (!?) power supply for a Magic Eye cathode ray tube VU meter and the <a href="https://www.aeronetworks.ca/2020/07/thermionic-valve-power-supply.html">same power supply circuit</a> can be used for a one valve RF receive amplifier.</p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJ6uQNqXiddc2lRQRxuuPNVKRhJTkOqpYmcyltG7DiWvHXAb5u3vxA63Wbq8ftHbvYBrMc3c4wcpcagrdpCzl6t-YsD7-gA2CdrQCIcPla_2KaPzbW-8neVeEMXZGgCEDVx9eBO7J6QTE/s800/nuvistor.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="800" data-original-width="800" height="210" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJ6uQNqXiddc2lRQRxuuPNVKRhJTkOqpYmcyltG7DiWvHXAb5u3vxA63Wbq8ftHbvYBrMc3c4wcpcagrdpCzl6t-YsD7-gA2CdrQCIcPla_2KaPzbW-8neVeEMXZGgCEDVx9eBO7J6QTE/w210-h210/nuvistor.jpg" width="210" /></a></div><div class="separator" style="clear: both; text-align: center;"><b>Small Sovtek 6CW4 Nuvistor</b></div><div class="separator" style="clear: both; text-align: center;">(Whatever you see on your screen is about life size!)</div><p>A problem with garden variety glass thermionic valve amplifiers is that they do not work at VHF or UHF frequencies. The big glass tubes are good for an electric guitar at baseband and shortwave radio, but not much beyond 50 MHz. However, there are special, low noise metal and ceramic valves, that were designed for this purpose and one can get small triodes that work up to 3 GHz.</p><p><i>Although these parts were in common use for about 30 years in TV receivers, most people don't know about them, because they are small and don't look like a vacuum tube. They look just like a metal can transistor, but with too many leads and instead of a silicon crystal, there is a vacuum inside!</i></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6uMa5wu2GUjdqUS8baPRXv7LdE5lW-h1QDJG-MXOEQ_dyKzLWizP3KVQFtltqYzny5WKljB6iAU4JGh-zCCe2TpqlWzuEq4Cz7JMH2y7fx22Ffl9BXpFiFTUt_tPwEiTgqzinAmke0vs/s1512/VHF-Amplifier.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1414" data-original-width="1512" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6uMa5wu2GUjdqUS8baPRXv7LdE5lW-h1QDJG-MXOEQ_dyKzLWizP3KVQFtltqYzny5WKljB6iAU4JGh-zCCe2TpqlWzuEq4Cz7JMH2y7fx22Ffl9BXpFiFTUt_tPwEiTgqzinAmke0vs/s640/VHF-Amplifier.jpg" width="640" /></a></div><p style="text-align: center;"><b>VHF Nuvistor RF Preamplifier</b></p><p>The above circuit should work for a 137 MHz weather satellite, using a 6CW4 Nuvistor triode. I got a handful from my favourite <a href="https://tubes-store.com">Electronics Junque Store</a> in Russia. </p><p>Since these tubes are very small, the internal parasitic capacitances and leakages are small. Therefore, they can be used with either Grid leak biassing, or with Cathode biassing. They behave almost like a NPN transistor, or a N-channel FET.</p><p>Electron tubes are very forgiving - just feed it some lecce and see what happens. I have never managed to blow up a tube. <i>It would require very special skillz to smoke a vacuum tube</i>.</p><p>Circuit design for Audio is different from design for RF. Audio circuits need to be linear and wide band over multiple octaves at base band. RF circuits need to be narrow band and reject signals both lower and higher, to reduce the noise and improve the SNR. For this reason, audio circuits are biassed with resistors only. Capacitors are used to stabilize the power and provide a slow roll-off to high frequencies to prevent oscillations. In RF circuits such as for the weather satellites at 136 to 137 MHz, the biassing and feedback are done with tuned circuits, to increase the Q and make the circuit narrow band.</p><p>Therefore, there are little coils that you should wind from magnet wire, but don't be scared of that, the designs are not critical. However, don't put them right next to each other. Try to keep them a little apart and at 90 degrees to each other, to minimize coupling.</p><p>Any RF circuit should be built as small as possible, to avoid problems with parasitic capacitance, inductance and coupling, but there is a limit to what one can do. <i> This circuit is about the highest frequency that one can still build successfully on a tag strip, but use a single ground point and use as few tags as possible.</i> A Christmas tree circuit with most parts soldered directly to the nuvistor is the best way to do it. You will need some thin heat shrink tubing to prevent shorts.</p><p>Another way to do it, is to cut some squares in the copper of a single sided PCB with a Dremel cutting wheel and build a blob circuit. Use a square in the middle as the ground, with some smaller lands around it. Drill some holes for the nuvistor leads and put it on the other side. It would be best to sketch the physical circuitry on paper before you start.</p><p>Wind the RF Coils from magnet wire around a 1/4 inch (5 mm) drill bit and slide it off. The input transformer matches a low impedance antenna to the high impedance Grid. Wind the negative feedback RF Coil on top of the 1M resistor - the 500p capacitor only blocks the high voltage DC. The output transformer 40T:10T can drive a low impedance antenna cable. If the tube oscillates - remove one turn at a time from the 28T coil on the resistor, till it stabilizes (Less turns = more negative feedback = lower gain).</p><p>Be sure to use large 2 W resistors and high voltage self healing (X rated) capacitors, else you may get smoke signals.</p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjYWs2Zep9IxefiW-y5R1dECJj-I_VeAfv6XgdbEaoiV6njwQvoUsk6hhFND8Gu3du5Ch1wnPLqSvJ4EBfX4CGL5wRCevohX7miWc99AuoePzEGavw0jSU8nZRD9tjS7yoQCf5rsviA4PU/s1578/Screen+Shot+2020-08-21+at+3.14.47+PM.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1404" data-original-width="1578" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjYWs2Zep9IxefiW-y5R1dECJj-I_VeAfv6XgdbEaoiV6njwQvoUsk6hhFND8Gu3du5Ch1wnPLqSvJ4EBfX4CGL5wRCevohX7miWc99AuoePzEGavw0jSU8nZRD9tjS7yoQCf5rsviA4PU/s640/Screen+Shot+2020-08-21+at+3.14.47+PM.png" width="640" /></a></div><p>These little triodes were widely used in television sets in the 1960s and 70s, so there are millions of them still available. The thimble size triodes are good up to about 1 GHz and they are not really any more difficult to use than a transistor - they just need a higher supply voltage and building the PSU keeps things interesting. </p><p><i>So, instead of the ubiquitous 2N2222 NPN transistor, you can use Nuvistors and amaze and confuse your fellow geeks when you hook a vacuum tube running at hundreds of volts to a Raspberry Pi or Arduino.</i></p><p>Well, now I don't have an excuse anymore and should grab the soldering iron and find a traditional old tobacco tin to house it in...</p><p>La voila!</p><p>Herman</p>Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com0tag:blogger.com,1999:blog-1589959253862674712.post-74171480410505482792020-08-15T10:56:00.015+02:002020-08-20T17:57:07.259+02:00GI-7b Microwave Triode<p>I recently obtained an ancient Rusky GI-7b microwave C-band triode. Packed in an innocent looking styrofoam container (I didn't know they had styrofoam in the bronze age - maybe that is how they floated the pyramid stones down the Nile!), it is quite a monster:</p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhItjQfrp7m2kMpqobwGH8lRw8fRa3KiTQTSxVIKG5VTBF4ONf9it5PhloT7y2qySmDCIqNJt0MuTYMe3uM4sJ8Zz2Ly3BCYgr6LxpL433k-gPAsmIICOyg1qd2f_eJktYvW-h6pp2gV84/s1607/IMG_6565.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1408" data-original-width="1607" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhItjQfrp7m2kMpqobwGH8lRw8fRa3KiTQTSxVIKG5VTBF4ONf9it5PhloT7y2qySmDCIqNJt0MuTYMe3uM4sJ8Zz2Ly3BCYgr6LxpL433k-gPAsmIICOyg1qd2f_eJktYvW-h6pp2gV84/s640/IMG_6565.jpg" width="640" /></a></div><p style="text-align: center;"><b>GI-7b Radar Amplifier Triode</b></p><p>This is a radar amplifier tube designed to operate while pulsing at up to 9 kV and 3 GHz.</p><p>To digress a bit, contrary to common perception, there are still lots of microwave electron tubes in use, for example microwave ovens, <i>radars, medical diagnostic equipment and satellites</i>. Travelling Wave Tubes are popular in satellite transmitters, because they are very efficient, very rugged and small. TWT amplifiers have been manufactured by the likes of Honeywell, Thales and others for over half a century - the frequency band just keeps going up and<i> they now operate in the Ka band</i>: <a href="https://aerospace.honeywell.com/en/learn/products/satellite-communications/traveling-wave-tube-amplifiers">https://aerospace.honeywell.com/en/learn/products/satellite-communications/traveling-wave-tube-amplifiers</a></p><p>What I would like to do one day, is build a Thermionic Valve satcom UHF preamplifier for use with a <a href="https://satnogs.org">SATNOGS</a> Raspberry Pi earth observation ground station - just for fun. I got some small Nuvistor tubes for that.</p><p>Really BIG electron tubes and oscillators are made in China by the Bejing Jenerator Co: <a href="https://jenerator.en.ecplaza.net">https://jenerator.en.ecplaza.net</a></p><p>There is also still a manufacturor of new electron tubes for audio amplifiers, the Xpo-Pul (Reflektor) factory in Saratov, Russia: <a href="http://rutubes.com/category/reflector-tube-saratov-russia/">http://rutubes.com/category/reflector-tube-saratov-russia/</a></p><p>The big GI-7 tube is supposed to have a vacuum inside - I hope it is still in there and that it didn't crawl out through a crack in the casing - it was designed for use in a battle tank, so it should be OK!</p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhlcN5otdS9yYWMfVrcDaL88ca6qOfW6dVYljWAgXsrDiYkhlMTGrvdqoj9zKhI_TeH36jMADjS7qKLKserU_8aq1KgbWRGEsE0Vn7A4ysfyDVf3DRCChI-8BtkEZh59MtgzWG8pQqrTHY/s1258/gi7b.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1258" data-original-width="868" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhlcN5otdS9yYWMfVrcDaL88ca6qOfW6dVYljWAgXsrDiYkhlMTGrvdqoj9zKhI_TeH36jMADjS7qKLKserU_8aq1KgbWRGEsE0Vn7A4ysfyDVf3DRCChI-8BtkEZh59MtgzWG8pQqrTHY/s640/gi7b.png" /></a></div><p style="text-align: center;"><b>Serious Data Sheet</b></p><p>The Heater and Cathode are at the bottom, the Gate in the middle and the Anode at the top. It is wired like a simpe Triode - no confusing extra grids as in a Pentode. I frequently wondered whether the extra grids of a Pentode really do anything useful, or are just there for marketing purposes. Hey, five are better than three right?</p><p>Electron Tubes tend to be very forgiving things and like a little kitten, will usually try their best to please you, if you warm them up nice and cozy and feed them some lecce. Therefore I'm wondering how it will do at a more pedestrian 335 VDC at 10 kHz baseband, in an audio amplifier output stage. The biggest problem will likely be the 12 V, 2 A heater current - 24 Watt to do mostly nothing - maybe it will work at half that.</p><p><i>One should not run a tube at kilovolts in your living room anyway, since you can get X-rays and Ozone, which are both not very nice.</i></p><p>Some Audiophile amplifiers have a random tube or two on display and wired such that if you remove the tube, the amp stops working, while it actually doesn't do anything at all, but since I grew up with tube fired radars in the Army, I'll find a way to make it work for real!</p><p><br /></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj73gCmVKaZdug-mY5exvGx_WIMNxmGy1IJoX1DdM-pLp3gw8y5ll2T7mLopdQ_gdPsFT0WdqdEDia0RP6PQakqxFAkip4dMT88gC0VZgeiHq0EsxsYQYLZM_FOxBf8CWOP7Kd9-2A4gow/s400/socketside.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="400" data-original-width="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj73gCmVKaZdug-mY5exvGx_WIMNxmGy1IJoX1DdM-pLp3gw8y5ll2T7mLopdQ_gdPsFT0WdqdEDia0RP6PQakqxFAkip4dMT88gC0VZgeiHq0EsxsYQYLZM_FOxBf8CWOP7Kd9-2A4gow/s0/socketside.jpg" /></a></div><p style="text-align: center;"><b>Crazy Socket</b></p><p>The socket for this valve is total overkill, so I'll have to make something more aesthetically pleasing.</p><p>UHF and Microwave Ceramic Valves are usually quite easy to solder to, since the contacts are silver plated. So I can run some copper steam tubes around the valve just for show: </p><p>RG405/U - <a href="https://www.pasternack.com/semirigid-0.085-rg405-50-ohm-coax-cable-copper-rg405-u-p.aspx">https://www.pasternack.com/semirigid-0.085-rg405-50-ohm-coax-cable-copper-rg405-u-p.aspx</a></p><p><i>Semi-rigid coax make nice looking steam tubes and shield the signals from 5G Audiophile interference, so you don't need a double layer tin-foil hat when you listen to my amps. <a href="https://www.aeronetworks.ca/2015/02/cool-amplifier.html">https://www.aeronetworks.ca/2015/02/cool-amplifier.html</a></i></p><p>Here is the complete thermionic valve data sheet:</p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBoRXchAU3-WActt-UXvAVQr3zw6X66-KHxSOn3W4ax2Vwk3uqwrZJq2fSKbvi_qNtBXyyEf6BYp2ImR8mwQaThhTv67FDVNLU68pfQ2ufTE-NKbXFXlR1-vZs7qg-OsrAJ6akmJcutAk/s1258/gi7b1.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1258" data-original-width="868" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBoRXchAU3-WActt-UXvAVQr3zw6X66-KHxSOn3W4ax2Vwk3uqwrZJq2fSKbvi_qNtBXyyEf6BYp2ImR8mwQaThhTv67FDVNLU68pfQ2ufTE-NKbXFXlR1-vZs7qg-OsrAJ6akmJcutAk/s640/gi7b1.png" /></a></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiwXiHgUoMJGCDGjK04d9xVWEqFWfCBe7fF8rHplEEpWMNDD26rrRxtkTznPN8lLbShz5hvfqm_A9oa-hrYgkayVUDOPt3tVhJn3TnNiC30D8Xu9m7I6R-71Vf2jp9s1vKZ_w_PpyfD5bg/s1254/g7b2.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1254" data-original-width="864" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiwXiHgUoMJGCDGjK04d9xVWEqFWfCBe7fF8rHplEEpWMNDD26rrRxtkTznPN8lLbShz5hvfqm_A9oa-hrYgkayVUDOPt3tVhJn3TnNiC30D8Xu9m7I6R-71Vf2jp9s1vKZ_w_PpyfD5bg/s640/g7b2.png" /></a></div><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi81ZWUBjUMxL_bs5mYW1GAYLgUCPS9Y1C32DYSGKy21utBsumfjM2YJ1rgA10Giz9r1jkC_W18Cy0-V2bc4ScLmnP8cRr9dqLCNKKH3RDO0_KEoxmvQDxMdWWTvD7mk23T8Ue-rvQBpLg/s1252/g7b3.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1252" data-original-width="866" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi81ZWUBjUMxL_bs5mYW1GAYLgUCPS9Y1C32DYSGKy21utBsumfjM2YJ1rgA10Giz9r1jkC_W18Cy0-V2bc4ScLmnP8cRr9dqLCNKKH3RDO0_KEoxmvQDxMdWWTvD7mk23T8Ue-rvQBpLg/s640/g7b3.png" /></a></div><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiT8I9TrR7P6ULPGwEomagx-TJi1uQaNrcKsvwKUYDwbjUgoeEivwCtGborPwd3ufaz_sFmnYT9uiTjh1GHUQR8-0E3o8_kjG049FkI80J-GI4Jg02iCvgtpNzujEdU5Z-jZ9pbAwO-PBA/s1250/g7b4.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1250" data-original-width="862" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiT8I9TrR7P6ULPGwEomagx-TJi1uQaNrcKsvwKUYDwbjUgoeEivwCtGborPwd3ufaz_sFmnYT9uiTjh1GHUQR8-0E3o8_kjG049FkI80J-GI4Jg02iCvgtpNzujEdU5Z-jZ9pbAwO-PBA/s640/g7b4.png" /></a></div><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjjmc_8c-lp6Emb4DemsRcluoTuwXpz4uloicj_HqpfmBfPmF4HTDD2XuuEwK3qsctKm4t5NGdX02_YJ9SI6Oy-Bs9EYS8SsGmTmy4VD0Ngr269ZfGZnelDHYeEIg25bbs1sG_N5klNBqA/s1258/g7b5.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1258" data-original-width="862" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjjmc_8c-lp6Emb4DemsRcluoTuwXpz4uloicj_HqpfmBfPmF4HTDD2XuuEwK3qsctKm4t5NGdX02_YJ9SI6Oy-Bs9EYS8SsGmTmy4VD0Ngr269ZfGZnelDHYeEIg25bbs1sG_N5klNBqA/s640/g7b5.png" /></a></div><p style="text-align: center;"><b>GI-7b Triode</b></p><p><i>Microamp per kilovolt </i>- Hmmm... Keep yer kotton picken fingers in yer pokkets!</p><p>What I want to do is far off the left-hand bottom end of all the curves, but it should work anyway.</p><p><br /></p><p>For now, it will have to rest some more in my Junque Bochs. </p><p>Maybe I'll get to it next year. </p><p>No rush.</p><p>The tube patiently waited 50 years already, so it can wait some more!</p><p><br /></p><p>La voila,</p><p>H</p><p><br /></p>Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com0tag:blogger.com,1999:blog-1589959253862674712.post-44559590246847086222020-07-24T17:55:00.053+02:002021-02-28T21:01:59.856+01:00Thermionic Valve Power Supply<h3 style="text-align: left;">Tinker, Tailor, Soldier, Sailor</h3>I like to tinker with old fashioned thermionic valve circuitry - tubes, for the 'Merrykins. It is strangely crude and simple and they make a friendly orange glow in the evening. However, powering the things is hard, due to the high voltages that are required to overcome the vacuum.<div><br /></div><div>The below picture shows how I build these toys. It happens on the fly. This is a hobby, so I don't kill myself with design calculations. The tag strips enable experimentation to adjust things till it works properly. The VU Meter even has a little transistor in there - sheer desperation!<br /><div><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgIjYJU2FdBjq4oci7KhAAxeEmy1v_6LpaFNYm9ThNatVSVOQUpWvhY-Ax0zvN2AkmEgcu-RhD34nDVFhclVKtKe2h6FVzZdFy9HjCzIHdKl1M9-mQw0Sb_RUBH4oNUew99882xtE23zdY/s2016/PSU-VU.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1512" data-original-width="2016" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgIjYJU2FdBjq4oci7KhAAxeEmy1v_6LpaFNYm9ThNatVSVOQUpWvhY-Ax0zvN2AkmEgcu-RhD34nDVFhclVKtKe2h6FVzZdFy9HjCzIHdKl1M9-mQw0Sb_RUBH4oNUew99882xtE23zdY/s640/PSU-VU.jpg" width="640" /></a></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div><div style="text-align: center;"><b>Transformerless Valve Power Supply</b></div><div><br /></div><div>One can use transformers, but they are big, heavy and expensive and shipping hunks of metal around the world make it even more so. It makes sense to use transformers if you build a high power circuit with multiple valves, such as a guitar amplifier, but a small circuit with only one or two valves presents a problem. </div><div><br /></div><div><i>For a small fun display project using Nixie, <a href="https://www.aeronetworks.ca/2016/08/audio-vu-meter.html">Magic Eye</a> or VFD tubes, you certainly don't want a huge box with a heavy transformer. However, the project should be self contained, with nothing else connected to it. Also, rather don't put a headset on a valve amplifier - a high voltage on your ears may be a little too hot!</i></div><div><i><br /></i></div><div><div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjBgRdi81b1w3ujOeGlPctZ8UjAghZLAvl76IehvkOKGCaNbbYoDhIJce0ebMOS3FxiWEd7Oahhxe5zLRMIRN4-slKg_wQ99xFTIP7yg8lLeic5WSkdA5YORI5U-FTFc7S81V1ZjhDH_iI/s2016/Magic1.jpg" style="display: block; padding: 1em 0px;"><img border="0" data-original-height="1512" data-original-width="2016" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjBgRdi81b1w3ujOeGlPctZ8UjAghZLAvl76IehvkOKGCaNbbYoDhIJce0ebMOS3FxiWEd7Oahhxe5zLRMIRN4-slKg_wQ99xFTIP7yg8lLeic5WSkdA5YORI5U-FTFc7S81V1ZjhDH_iI/s640/Magic1.jpg" width="640" /></a></div><div class="separator" style="clear: both; text-align: center;"><b>VU Meter Top Panel</b></div></div><div><br /></div><div>This article describes how to build a <i>reactive heater supply</i> and a <i>rectified mains high tension supply</i>, that will not break the bank, or your back, or risk burning your house down.</div><div><br /></div><div>The problem is that the mains supply is 'dirty'. <i> The Earth wire sometimes isn't earthed. The Neutral and Live wires can be swapped. </i> There can be high voltage spikes caused by air conditioners, industrial machinery and lightning. So if you want your circuitry to last longer than a few months, then you need to protect it carefully. You can either use a big hunk of transformer iron and copper to provide the protection, or you can use a few carefully selected specialized components, to do that with a little more finesse.</div><div><br /></div><h3 style="text-align: left;"><b>Circuit Protection</b></h3><div>You should combine the two circuits below after the choke. I drew them separately to make it more clear.</div><div><br /></div><div><div><b>Safety Capacitors</b></div><div>A Safety Capacitor is self healing and self extinguishing. If it gets zapped by a high voltage spike, then it will carry on working despite the puncture. Eventually, the capacitor may fail, but while it may smoke, it will not burst into flames and burn your house down. They are expensive, but rather cheaper than a new house. It is the big blue block in the picture.</div><div><br /></div><div><b>Polyfuse</b></div><div>A polymer fuse typically contains little spheres of metal inside a rubber compound. Normally the spheres make contact and the fuse conducts. When it heats up, the rubber relaxes and the spheres lose contact, interrupting the current. When the device cooled down, it will again conduct. In case of a fault, it will cycle on/off. In an extreme failure, it will melt permanently and open the circuit. <i>You absolutely must use a fuse. </i> You <i>will</i> get shorts, arcs, or blown parts from time to time, when working with high voltages.</div><div><br /></div><div><b>Common Mode Choke</b></div><div>A common mode choke will block current spikes that are the same phase on both the live and neutral wires - for example lightning induced spikes. There are two ways to wind a common mode choke: </div><div>1. Double up some thin hookup wire and feed it through a toroid ten to twenty times, but then it is prone to arc between the two windings - it is easy to damage the wire coating while winding on a toroid with sharp edges (some toroids are really dreadful).</div><div>2. Make two separate windings on the 'left' and 'right' sides of the toroid for beter isolation. Start on the outside and dive into the middle - keep going. It <i>seems</i> to be opposite, but it is not, the two windings rotate the same way. </div><div><br /></div><div>To hold the windings, drop the toroid onto a sharpened pencil held upright in a vice, then glue it with epoxy or a drop of varnish.</div><div><br /></div><div><b>Gas Arrestors</b></div><div>Place a gas arrestor between both Live and Neutral to Ground. A gas arrestor is a non-linear device (it is a special neon bulb). A high voltage spike will cause the gas to form a plasma and conduct. It will continue to conduct, until the voltage subsided. In the extreme, it will arc over between two sharp points. This will absorb both common and differential mode spikes on the mains wires. You can get centre tapped ones and single ones - your choice. </div><div><br /></div><div>You can also use two zinc oxide MOVs, but since we are talking about vacuum tubes, gas discharge arrestors are more cool.</div></div><div><br /></div><div><b>Turret Boards and Terminal Strips</b></div><div>I build olde fashioned circuits on olde fashioned Turret Boards and Terminal Strips. These are authentic early 20th century strips of Bakelite with solder pins or eyelets <a href="https://www.digikey.com/product-detail/en/tubedepot/534-831/2197-534-831-ND/10488281">https://www.digikey.com/product-detail/en/tubedepot/534-831/2197-534-831-ND/10488281</a></div><div><br /></div><div>Building on these strips is error prone. This time I managed to solder a resistor directly across live and neutral - it made a nice flash. So it is good to have a self resetting Polyfuse. If you prefer glass tube fuses, be sure to have a dozen available, since they only give you one shot at a mistake!</div><div><br /></div><div><h3 style="text-align: left;"><b>Heater Current Supply</b></h3><div>The heater supply uses a ballast capacitor to drop the excess voltage, without generating heat as you would with a series resistor. This is a nifty trick which is smaller than the smallest available 6V3 transformer, but your need to get a capacitor that is designed for the purpose and it is therefore much bigger and more expensive than a garden variety capacitor. They are known as <i>Safety Capacitors</i>, or <i>Motor Run</i> capacitors and can continuously source AC current.</div><div><br /></div>Heater voltage for two valves in series = 12.6 V <br />Heater Current = 300 mA
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<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh52FE9zLlE9KwWmLv1Jb4xBRXDqUKXDYKCfWhHlORvM6AjwB-1zWgzl3fhHqC_d2r5wt1EHZHqriefJllzi5eY9fuPguc14hoRPfrSZ8gq6fwxtJzOK6ecxYdBBE-umIxyfen2fsdcYKY/s1965/HeaterSupply.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1085" data-original-width="1965" height="276" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh52FE9zLlE9KwWmLv1Jb4xBRXDqUKXDYKCfWhHlORvM6AjwB-1zWgzl3fhHqC_d2r5wt1EHZHqriefJllzi5eY9fuPguc14hoRPfrSZ8gq6fwxtJzOK6ecxYdBBE-umIxyfen2fsdcYKY/w500-h276/HeaterSupply.jpg" width="500" /></a></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div style="text-align: center;">(I used an ancient manual CAD program, known as a pencil)</div><p style="font-family: "helvetica neue"; font-size: 12px; font-stretch: normal; line-height: normal; margin: 0px; min-height: 14px;"><br /></p>
Mains: 220 VAC at 50 Hz <br />Vdrop = 220 V - 12.6 V = 207.4 V RMS </div><div>(Yankees need to recalculate using 115 V and 60 Hz)<br /><br />Capacitor impedance = 1 / 2 x Pi x f x C </div><div><br /></div><div>4.7 uF: <br />Z = 1 / 2 x 22 / 7 x 50 x 4.7 x 10^-6 = 677 Ohm imaginary<br /><br /></div><div><div>Assuming that the mains voltage is much larger than the heater voltage, we can ignore the 90 degree phase shift for the following calculations and simplify, just because I'm lazy to punch more buttons on the calculator:</div><div><div>Vin^2 = Vc^2 + Vh^2</div></div><div>Vin ~= Vc + Vh</div><div><br /></div>230 V Supply: <br />217.4 V / 677 Ohm = 321 mA <br /><br />220 V Supply: <br />207.4 V / 677 Ohm = 306 mA <br /><br />Capacitor: 871-B32926A4475K <br />Safety Capacitors, 4.7uF, 10%, 350Vac, LS, 37.5mm <br /><a href="https://eu.mouser.com/ProductDetail/EPCOS-TDK/B32926A4475K?qs=ZxCuU5VshqBvujh9kykPlw%3D%3D">https://eu.mouser.com/ProductDetail/EPCOS-TDK/B32926A4475K?qs=ZxCuU5VshqBvujh9kykPlw%3D%3D</a> <br />$10.13 </div><div><br /></div><div><div>Initially, I did not have a 4.7 uF safety capacitor available, so at first I used five caps in parallel for the prototype, which is of course 5 times more expensive and bulky, but it took a while for the next Mouser delivery to get here.</div><div><br /></div></div><div>Also put a 1 Megohm 2 Watt bleed resistor in parallel with the capacitor and a 22 Ohm, 5 W resistor in series with the capacitor, to limit the start-up current until the heaters warmed up, because the heaters are non-linear and have a much lower resistance when cold (~6.5 Ohm vs ~22 Ohm).</div><div><br /></div><div>Test the heater supply with a 22 Ohm (one valve heater) to 47 Ohm (two valve heaters), 10 Watt resistor. Once wired to the valves, measure the current and voltage and adjust the series resistor if necessary. The green thing next to the blue block in the picture is a 22 Ohm 5 Watt resistor (<i>The schematic above still says 10 Ohm, but 22 Ohm, 5 Watt works better for me!</i>).</div><div><br /></div><div>Be sure to wire the two tube heaters in series. When you turn the system on, the current will slowly go down and the voltage will slowly go up, as the heaters heat up and their resistance increase. Eventually, the tubes should be glowing a nice and friendly orange and the voltage should be around 12V6 AC. I measured up to 11.9 V AC, which is gud enuff. If the voltage and current is way out, then you need to adjust the series resistor (don't touch it - it gets very hot!).</div><div><br /><h3 style="text-align: left;"><b>High Tension Supply</b></h3><div>The high tension for a typical valve circuit needs to be in the order of 100 to 300 VDC. Valves are very forgiving - when they work, they work - and contrary to popular belief, they last for many years. Lots of the parts on the market were 'lightly used' in a military installation for 30 or 40 years, half a century ago and they still work!</div><div><br /></div><div>You can get the HT voltage by rectifying the European mains supply and then drop the excess with a series resistor on the valve Anode. Use high voltage diodes with a rating higher than the protection circuitry and another safety capacitor to stabilize the voltage. (If you live in the US of A or Canada with 115 VAC, then you need to make a voltage doubler instead.)</div><div><br /></div><div><i>Note that most European plugs can be inserted any which way.</i> If you live in Europe, then it is probably a good idea to install two fuses, in both the L and N leads and also use a DPST toggle switch.</div><div><br /></div>Mains: 220 VAC @ 50 Hz <br />Bridge rectifier Vht = 1.414 x 220 V = 311 VDC <br /><br />
<div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiz0L0Z81zReJ-IsaH3kHTCc9QdjEFI6te5XUDKGtm_mBOJetMihd_kIoiLP6WpzP87lDWCZ04Pf9u8nzUSjEU9bB2CdNsQDARSrWBe_PWeX7s5JNj4J7TjPaEixhlRcUwRB2ExEjWaxgE/s1970/ht-supply.jpg" style="display: block; padding: 1em 0px;"><img border="0" data-original-height="763" data-original-width="1970" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiz0L0Z81zReJ-IsaH3kHTCc9QdjEFI6te5XUDKGtm_mBOJetMihd_kIoiLP6WpzP87lDWCZ04Pf9u8nzUSjEU9bB2CdNsQDARSrWBe_PWeX7s5JNj4J7TjPaEixhlRcUwRB2ExEjWaxgE/s640/ht-supply.jpg" width="640" /></a></div><div class="separator" style="clear: both; text-align: center;"><br /></div><p style="font-family: "helvetica neue"; font-size: 12px; font-stretch: normal; line-height: normal; margin: 0px;"><br /></p>
<p style="font-family: "helvetica neue"; font-size: 12px; font-stretch: normal; line-height: normal; margin: 0px; min-height: 14px;"><br /></p>Mains: 230 VAC @ 50 Hz <br />Bridge rectifier Vht = 1.414 x 230 V = 325 VDC <br /><br />Mains: 240 VAC @ 50 Hz <br />Bridge rectifier Vht = 1.414 x 240 V = 339 VDC <br /><br />Diode, 1000V, 1A: 1N4007 (1 off or 4 off) <br />863-1N4007G <br /><a href="https://eu.mouser.com/ProductDetail/ON-Semiconductor/1N4007G?qs=y2kkmE52mdOJ200gEKhp%2FQ%3D%3D">https://eu.mouser.com/ProductDetail/ON-Semiconductor/1N4007G?qs=y2kkmE52mdOJ200gEKhp%2FQ%3D%3D</a> <br />$0.21 <br /></div><div><br /></div><div><div>Capacitor: Ceramic, 1 uF 1000 VDC high dissipation</div><div><a href="https://eu.mouser.com/ProductDetail/AVX/SV09AC105KAR?qs=0CLa%252BqihjdEi3XTt3cTS0Q%3D%3D">https://eu.mouser.com/ProductDetail/AVX/SV09AC105KAR?qs=0CLa%252BqihjdEi3XTt3cTS0Q%3D%3D</a></div><div>$24.93</div><div><br /></div></div><div>Capacitor: Electrolytic, 100 uF 450 VDC</div><div><a href="https://eu.mouser.com/ProductDetail/KEMET/ESU107M450AN9AA?qs=HXFqYaX1Q2xqLzZAhsqNoA%3D%3D">https://eu.mouser.com/ProductDetail/KEMET/ESU107M450AN9AA?qs=HXFqYaX1Q2xqLzZAhsqNoA%3D%3D</a></div><div>$3.44</div><div><br /></div><div>Capacitor: Ceramic, 10 nF 1000 VDC</div><div><a href="https://eu.mouser.com/ProductDetail/Vishay-BC-Components/S103K75Y5PN83K0R?qs=sGAEpiMZZMuMW9TJLBQkXp4eEQ3KTPcvN5Fy0dDlhf8%3D">https://eu.mouser.com/ProductDetail/Vishay-BC-Components/S103K75Y5PN83K0R?qs=sGAEpiMZZMuMW9TJLBQkXp4eEQ3KTPcvN5Fy0dDlhf8%3D</a></div><div>$0.59</div><div><br /><br /></div><div>I used a single diode, half wave rectifier and a 10 uF, 350 V DC capacitor for the prototype, till my Mouser order arrived. That is the advantage of terminal boards - easy to change and fix later.</div><div><br /></div><div>However, the 10 uF, 350 VDC electrolytic capacitor was a very bad idea. It self oscillated, thus generating a very high voltage >1000V, with various weird and wonderful things happening as a result, but since the rest of the circuit wasn't built yet, it did not cause further damage. </div><div><br /></div><div>Eventually I replaced it with a Ceramic 10 nF 1000 V, paralelled with a Ceramic 1 uF 1000 V, paralelled with an Electrolitic 100 uF 350 VDC capacitor, which calmed the HT supply down and since it now finally works, I'll just leave it like that. How this works, is that the X rated ceramic capacitor has the lowest impedance and handles the brunt of the ripple, which is then further smoothed by the 100 uF Electrolytic and the little 10 nF in parallel with it, damps any self oscillations in the Electrolytic capacitor.</div><div><br /></div><div>Note that you must use 2 Watt resistors to discharge the capacitor bank and drive the Neon indicator bulb, not because of the power dissipation, but because of the high voltage. A 1/4 Watt resistor will arc and make cryptic smoke signals.</div><div><br /></div><div><h3 style="text-align: left;"><b>Protection Circuitry</b></h3>Resettable fuse: 576-600R150-RAR <br />Voltage: 350 V maximum <br />Current 300 mA <br /><a href="https://eu.mouser.com/ProductDetail/Littelfuse/600R150-RAZR?qs=sGAEpiMZZMsgjL4JkW1EEUfdUrimm9NEBXyO2non48E%3D">https://eu.mouser.com/ProductDetail/Littelfuse/600R150-RAZR?qs=sGAEpiMZZMsgjL4JkW1EEUfdUrimm9NEBXyO2non48E%3D</a> <br />$1.08 <br /><br />Gas arrestors: From each mains wire to ground <br />Gas arrestor: 652-2045-40-BT1LF <br />Spark over: 400 V <br /><a href="https://eu.mouser.com/ProductDetail/Bourns/2045-40-BT1LF?qs=qcv5MX6YzaKx5e3H%2FmTy%2Fg%3D%3D">https://eu.mouser.com/ProductDetail/Bourns/2045-40-BT1LF?qs=qcv5MX6YzaKx5e3H%2FmTy%2Fg%3D%3D</a> <br />$0.819 <br /><br />Common mode choke: 10 to 20 turns, double wound <br />Toroidal core: 80-ESD-R-10E <br />Size: 10 mm OD, 5 mm ID, 5mm height <br /><a href="https://eu.mouser.com/ProductDetail/KEMET/ESD-R-10E?qs=BenOyfdfAroZzp6LE7YowQ%3D%3D">https://eu.mouser.com/ProductDetail/KEMET/ESD-R-10E?qs=BenOyfdfAroZzp6LE7YowQ%3D%3D</a> <br />$0.18<br /></div><div><br /></div><div>Also put a 1 Megohm 2 Watt bleed resistor in parallel with the capacitor banks. You won't be sorry if the capacitor is safely discharged when you touch the wires...</div><div><br /></div><div>Test the HT supply with a 33 kilohm, 5 Watt resistor.</div><div><br /></div><div><br /></div><div><b>Indicator Lamp</b></div><div>What is a power supply without an indicator lamp? A little NE2 neon bulb with a 1M to 3M3 resistor in series over the 325 VDC supply output will work, but it will be boring. If you put a 470 nF or 1 uF capacitor in parallel with the bulb then it will flash - a relaxation oscillator. </div><div><br /></div><div>The capacitor will never see a voltage higher than about 90 V, but if the neon would ever pop, then the cap may pop too, so it is best to use a 1000 V ceramic or self healing safety capacitor. </div><div><br /></div><div>Please don't use a blue LED with valves. A blue LED in a valve circuit should be illegal - A crime against humanity.</div><div><br /></div><h3 style="text-align: left;">Personal Safety</h3><div>When you work with thermionic valves, be sure to put a rubber carpet on the floor and house your project in a well insulated ABS, bakelite or wood enclosure, away from curious little prying fingers!</div><div><br /></div><div>For this hobby, one not only needs a soldering iron, one also needs quite a serious woodworking shop - bench saw, drill press, router, planar, sander, maybe even a CNC machine!<br /></div><div><br /></div><div>Power on: Over the years, I have had multiple components explode at first power up, so do put a transparent plastic box over the project and stand some distance away when turning it on. A capacitor may explode, or something may arc and maybe you can see what happened through the plastic shield and smoke...</div><div><br /></div><div><br /></div><div>La Voila!</div><div><br /></div><div>Herman</div></div></div>Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com2tag:blogger.com,1999:blog-1589959253862674712.post-42339613060394131222020-07-19T15:36:00.010+02:002020-07-25T09:17:10.084+02:00C-Band Yagi Antenna<h3 style="text-align: left;">A Formal Bow Tie Event</h3>I have made a few PCB antennas and the Yagis worked well, but they were very narrow band. So I tried to improve that by making the elements conical - or in this case, since it is 2D PCB antenna, triangular.<div><br /></div><div>I think it is a fairly unique idea and I certainly haven't seen a picture of a PCB antenna like this before. The Driven element and first director are flared to 3 mm (since there is no more space) and the Reflector and other Directors are flared to 10 mm.</div><div><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhOLGtB1twQe0QmF7_o8OmvpYkCve2cwZLnyPIMJ7A8YX_z0lp7fFA1ti9gI11CkG9hJIIvRZYIdpPnb-pPyZrDZ0up68UtV8ByptAjI2jtZ5jXBhqketYtBlsomVr5nd4TCsj2zP-oFNU/s1225/yb5.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="765" data-original-width="1225" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhOLGtB1twQe0QmF7_o8OmvpYkCve2cwZLnyPIMJ7A8YX_z0lp7fFA1ti9gI11CkG9hJIIvRZYIdpPnb-pPyZrDZ0up68UtV8ByptAjI2jtZ5jXBhqketYtBlsomVr5nd4TCsj2zP-oFNU/s320/yb5.jpg" width="320" /></a></div><div style="text-align: center;"><b>Wide Band Yagi with Unbalanced Co-ax Feed</b></div><div><br /></div><div>I'll see what happens once the conformal coating dried and I hooked up a cable.</div><div><br /></div><div>It is the same design I used before - I just flared the elements and left out the last 2 directors:</div><div><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjAJ8s9GXdRjKUiel3GKc6tlCR36Cn6ocvLhLoPAH7wiOjph0SP_Qyhyco55BJWLrfp1vCGbllo8ZZTVZCNe00zvPX-u6R4AJ-dy5acazSOYA26hOgbyUZ2RcngyBrSMpWppc1zKYUmnnY/s400/Phased-Array-5GHz-Design.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="400" data-original-width="362" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjAJ8s9GXdRjKUiel3GKc6tlCR36Cn6ocvLhLoPAH7wiOjph0SP_Qyhyco55BJWLrfp1vCGbllo8ZZTVZCNe00zvPX-u6R4AJ-dy5acazSOYA26hOgbyUZ2RcngyBrSMpWppc1zKYUmnnY/s320/Phased-Array-5GHz-Design.png" /></a></div><div><br /></div><div>This way I can compare the two antennas with each other. I didn't bother to simulate it - I just went ahead and machined it to see what happens.</div><div><br /></div><h3 style="text-align: left;">Antenna Gain</h3><div>Initial tests showed that the gain is about 5 dBi which is typical for a 5 element Yagi and the bandwidth of the new antenna is much wider than the conventional old one, which is very promissing, but I need to work on my RF cables, connectors and calibration kit, to get proper graphs, since the VNA seems to be out of calibration.</div><div><br /></div><div>I don't have an anechoic chamber - I hold two antennas in my hands and rotate them 90 and 180 degrees to see what is going on - good enuff!</div><div><br /></div><h3 style="text-align: left;">Performance Graphs</h3><div>I eventually charged the battery of my VNA (<i>Having decent power sure helps!</i>), reread the manual and reset the calibration (<i>Func Shift 7</i>). I also verified that there is no significant difference between <i>Sys Cal</i> and <i>User Cal</i> with my cables, so it is good to go.</div><div><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4bQEv5bPp5arL9KFbSWtHw4y4lA-l1nFnT15Jm-wcmQkvdqLnED4Zu5SN355g3rPub4BmeWxR0KWpeZ0NTauOo5NORdz2klrXVlB2ZXSVGmHbn0l6McxxmTNEMriHrOtSS0e-CyOKnZc/s2016/yb-smith.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1512" data-original-width="2016" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4bQEv5bPp5arL9KFbSWtHw4y4lA-l1nFnT15Jm-wcmQkvdqLnED4Zu5SN355g3rPub4BmeWxR0KWpeZ0NTauOo5NORdz2klrXVlB2ZXSVGmHbn0l6McxxmTNEMriHrOtSS0e-CyOKnZc/s320/yb-smith.jpg" width="320" /></a></div><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEif2a1fLJhhQrov2OWz02S31jeAYmOpxauGlRFDQli4AQw9BAWbvYgUEkf-uRXkdN43sZRhuBgb1Uxvwvq0kftq6qGAYBWN-e0rAiL_RR4DVVdouQ3ysUlNpuC6M7R7aUTcFpmAkxxTvWo/s2016/yb-vswr.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1512" data-original-width="2016" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEif2a1fLJhhQrov2OWz02S31jeAYmOpxauGlRFDQli4AQw9BAWbvYgUEkf-uRXkdN43sZRhuBgb1Uxvwvq0kftq6qGAYBWN-e0rAiL_RR4DVVdouQ3ysUlNpuC6M7R7aUTcFpmAkxxTvWo/s320/yb-vswr.jpg" width="320" /></a></div><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivoKicl55dLBBCcIf0rqGamjihil1QepSXJTPFXyRBp8Kpgf60wtyjRAPHMUqhSaCd8E9liQe6JlOAR79SMBGwsXTa8cNe9TIiRgGsVCVE5IF3vG13DN8_o9H-Sr_-1-vvOMZ_qhl6SK8/s2016/yb-impedance.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1512" data-original-width="2016" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivoKicl55dLBBCcIf0rqGamjihil1QepSXJTPFXyRBp8Kpgf60wtyjRAPHMUqhSaCd8E9liQe6JlOAR79SMBGwsXTa8cNe9TIiRgGsVCVE5IF3vG13DN8_o9H-Sr_-1-vvOMZ_qhl6SK8/s320/yb-impedance.jpg" width="320" /></a></div><div><br /></div><div style="text-align: center;"><b>Bandwidth of 120 MHz at 3.1 GHz</b></div><div><br /></div><div>For comparison, here is the previous simpler antenna with 1 mm wide straight elements:</div><div><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSnoOu-LIlbBc4k_kaeFxuy1_h_TVuqOin1-rltNKSkJH_46FU1kNwJaWIKwcq5CLzQn8EyZ9E_MkrNpXfZZm77T2xALwSWqPYgojRYOePhK3uDenyLSIs-Gtal_5BUmHMhxX4RRgfR8g/s2016/nb-vswr.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1512" data-original-width="2016" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSnoOu-LIlbBc4k_kaeFxuy1_h_TVuqOin1-rltNKSkJH_46FU1kNwJaWIKwcq5CLzQn8EyZ9E_MkrNpXfZZm77T2xALwSWqPYgojRYOePhK3uDenyLSIs-Gtal_5BUmHMhxX4RRgfR8g/s320/nb-vswr.jpg" width="320" /></a></div><div class="separator" style="clear: both; text-align: center;"><br /></div><div style="text-align: center;"><b>Bandwidth of 30 MHz at 3.38 GHz</b></div><div><br /></div><div>A low VSWR is important for a transmit antenna. Modern day radios have Gallium Arsenide semiconductor drivers that can get damaged very easily by high voltages. The better radios have self protection circuits that will reduce the output power if there is a mismatch, but El Cheapo radios may simply heat up and melt down.</div><div><br /></div><div>Vacuum tube radios can handle enormous voltages, so the old clunkers can simply be tuned for maximum smoke, but the missus may not want to have a hot and sizzling 1 meter tall Klystron tube in the living room, although it could be quite a discussion piece. Travelling Wave Tubes are still used in some K band satellite transmitters, so vacuum tubes are not just ancient relics of microwave ovens!</div><div><br /></div><h3 style="text-align: left;">Summary</h3><div>Flaring the antenna elements to 3 mm and 10 mm does help significantly to widen the bandwidth of the Yagi antenna by 400% and it still has the nice linear Phase, VSWR and Impedance characteristics of a conventional Yagi, but the antenna is still quite narrow band, compared to a Log-Periodic antenna for example.</div><div><br /></div><div>The centre frequencies are somewhat different, because the new one is made on FR2 and the old one on FR4, but I also plotted the new one more accurately in KiCAD. To get a PCB antenna exactly on the frequency you want, will take three to five iterations. That is just the nature of the game.</div><div><br /></div><div>I think that the bandwidth can be further widened, by inserting cross pieces to make the elements more like cones. Maybe I'll try a <a href="https://www.youtube.com/watch?v=_Q8CpaejCk8">Conehead</a> antenna another day.</div><div><br /></div><div><br /></div><div>Have Fun!</div><div><br /></div><div>Herman</div>Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com4tag:blogger.com,1999:blog-1589959253862674712.post-17144962349475789962020-07-13T12:32:00.004+02:002021-02-28T21:07:09.745+01:00Bar Clamp<div dir="ltr" style="text-align: left;" trbidi="on">
<b>Clamped Up</b><br />
I needed a little clamp, but we were in Covid19 lock down. So I made one. No transistors, no batteries, no thermionic valves, no flashing neon bulbs!<br />
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There are many complicated ways to make a bar clamp, but I prefer the simple way. A picture is worth a thousand words:<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_FdXdDkAMiAJKmtfY0s6LTKSmQQquEBAqHKYnU4n0CQvy744uIaHFXlwiQ7deU7bUkZHj8cUl8qv-3Gu-uKEBkGrtNOgxLcTUZNgsMhxup1qxJH2MO9hdSXZy5I6lq7uORHxRtOZdb3I/s1600/BarClamp.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1200" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_FdXdDkAMiAJKmtfY0s6LTKSmQQquEBAqHKYnU4n0CQvy744uIaHFXlwiQ7deU7bUkZHj8cUl8qv-3Gu-uKEBkGrtNOgxLcTUZNgsMhxup1qxJH2MO9hdSXZy5I6lq7uORHxRtOZdb3I/s320/BarClamp.jpg" width="240" /></a></div>
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<b>Mini Bar Clamp</b></div>
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It can't be simpler:<br />
<ul style="text-align: left;">
<li>One 6 mm dowel rod</li>
<li>One 6 x 80 mm bolt</li>
<li>One 1" nail</li>
<li>Ten popsicle sticks</li>
<li>Glue</li>
</ul>
Yup - ten popsicle sticks glued together, made a small piece of plywood, that I could cut up for the clamp jaws. You can use the exact same method to make a big bar clamp. You don't need a super long lead screw, just a long bolt and a whole lot of little holes to adjust the other end of the clamp. Scale it up as required for size and strength.<br />
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How do I keep the movable jaw in place? Some funny putty (Press Stick) in a hole. It churns around in there and keeps the block from falling off the end of the bolt - a little piece of rubber will also do. The best way would be to file a ring in the end of the bolt, cut a washer in two and glue that into the block, but that is a lot of hassle - another day - do, do that on a big clamp.</div><div dir="ltr" style="text-align: left;" trbidi="on"></div><div dir="ltr" style="text-align: left;" trbidi="on"><br /></div><div dir="ltr" style="text-align: left;" trbidi="on">Is it really worth making a bar clamp? Of course not! One can buy a perfect clamp for a few Dollars, but what is the fun in that and what else can you do with a bag of craft store pop sticks?</div><div dir="ltr" style="text-align: left;" trbidi="on"><br />
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Have fun!<br />
<br />
Herman</div>
Herman J.H. Oosthuysenhttp://www.blogger.com/profile/17377909195162655283noreply@blogger.com0