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Showing posts from 2019

T'is The Season of Blinky Lights

I like to play with old fashioned neon tubes.  They make a soft and friendly mystical glow and are especially good for a night light, so you don't fall down the stairs. Seven of Nine More here:  Olde Skool Blinken Lights ...and for really, really slow blinky lights, see the VASCO project at https://vasconsite.wordpress.com Have fun! Herman

Glue Pull Dent Removal

My little Dustbin suffered a parking garage bump from a much bigger SUV with a bumper above the level of mine - dunno who dunnit.  To pass the yearly road safety inspection, all crash damage must be repaired, but the law doesn't say anything about the quality of the repair... Since I didn't want to spend money on an old clunker, I yanked the dent out with hot glue and dowel rods.  This works, because modern paint adheres extremely well to the metal.  It really doesn't come off easily. There are many videos on Yootoob about no repaint hot glue dent pulling.  Everyone wants you to buy their fancy tools and special glue.  You don't really need any of that and prolly have everything you need in your tool box already.  I recommend watching a couple of those videos before you start, to give you some ideas. I know how to do serious body work, I can weld anything that will melt and spray paint whatever needs paint, but where I live now, I don't have the tools - or th

Olde Skool Blinken Lights

How did people make blinky lights before transistors, LEDs and the venerable 555 timer? T'was the Night Before Christmas - Only Passive Parts If you would venture outside during a sociable hour, you should see a very bright yellow lamp in the sky - the sun - yeah, that one - amazing isn't it? The sun is a huge nuclear powered neon lamp - not the kind of thing you can make in your radio shack, but if you go and dig deep into the scary nether regions of your junk box, you may find a couple of NE2 neon bulbs.  (Put on some gloves, you may have to dig so deep you may cut a finger - I did... yeow...) New bulbs only cost a few pence, so if you are scared of spiders, or other unspeakable things lurking in the bottom of your junk box, next time you order toys from Digikey or Mouser, include a handful of them.  Neons can make any new project look retro-cool with a mystical yellow glow. A neon bulb starts to glow at about 90 Volt and stops glowing at about 60 Volt. 

Differential Backups Made Simple

To backup or not to backup.  That is the question. Who likes to make backups? Anyone, Anyone? Hmm, I thought so... Versioned Backups I prefer to make backups with very simple tools, since when things go south, I don't want to have to install a complicated system just to get my data back. Most UNIX backup systems are based on rsync and by using a careful system of  hard links (multiple new names for the same old file), differential backups can save you oodles of disk space in the long run, while making it very easy to step through an archive and retrieve specific versions of old files: https://www.nongnu.org/rdiff-backup/ http://www.mikerubel.org/computers/rsync_snapshots/ https://popey.com/blog/2020/12/straightforward-linux-backups-with-rsnapshot/ Three for the Price of One The original article by Mike Rubel describes how to keep three backups for the price of one, using a combination of hard links and rsync . That idea then spawned the rsnapshot (pull) and rdiff-

Micro Wind Genny

Who didn't play with whirlygigs as a child?  I sure had hours of fun with paper and wood twirly whirlies, but I frequently wondered about making something bigger, that can produce useful power. Fifty odd years later... Little Alternator with 6 LEDs A small three phase alternator that can be had for the princely sum of about $5 from aliexpress.com, can produce a few Watts of power.  Twirl it by hand to light up 6 LEDs. I took it to our production manager Siegfried Losch, who is always willing to play with a new toy and we stuck it into a drill press.  With no load, it generated 14V AC rms when running at 3000 rpm.  So it can charge a 12V SLA motor cycle battery when hooked to a high speed engine, but it will not do much with a wind rotor that will only turn at about 200 rpm or less. If you are content with 6 or maybe 12 LEDs to light up a little tree in your backyard, then you can skip all the electronics below, get some balsa and go carve a propellor. If you are lik

Driving A 900 MHz Quad Patch Array Antenna

A Circular Polarized Quad Patch Array for the 900 MHz ISM Band Driving a patch array antenna is a tricky and multidisciplinary affair - a combination of electrics, magnetics and mechanics - where theory meets reality.  Patch antennas are useful between about 1 and 5 GHz.  Below that, they are too big and above that, too small to be practical for the manufacturing tolerances of a hobbyist.  For L, S and C-band, a radio amateur can use patches with good effect, using not much more than tin snips and a nibble tool. 902-928 MHz ISM Band LCP Quad Patch Antenna The patch antenna theory can be explored with a simulation program such as NEC2: https://www.aeronetworks.ca/2018/07/patch-antenna-design-with-nec2.html You could make an array with any number of patches, but more than four would be a whole lot of hassle.  A SAR radar antenna may have 300 tiny little patches.  However, a two by two is about the limit of my patience. Any piece of metal within half a wavelength of an anten