Skip to main content

Posts

Showing posts from August, 2019

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