For my German-speaking friends: you may be familiar with ELV’s magazine, the ELV Journal. As of this year, they’ve discontinued the print magazine, which will now continue as digital-only — for free. Until now, accessing the journal archive required a subscription to the magazine, now all of it, past and present, is totally free.
It’s found here:
https://de.elv.com/journal/fachbeitraege/For the youngest among you, who’ve mostly experienced ELV as just a peddler of smart home crap and some educational products (in the style of Arduino breakout boards), it may come as a surprise that ELV used to have kits for everything. You could equip your entire lab with ELV test gear, from power supplies to multimeters to oscilloscopes and soldering stations. Those serious kits, and the explanations of how they work, were awesome.
In particular, the older issues are interesting, because the articles about their kits have full schematics and PCB layouts (usually), and don’t require any firmware.
Sadly, over time more and more of their kits were based on microprocessors or programmable logic devices, which they never provided source code for, making them impossible to reproduce directly. Many of the most interesting kits from the 1990s cannot be reproduced for this reason. Basically everything before 1987 is microprocessor-free, after that it slowly changes.
Some good examples:
https://de.elv.com/elv-serie-7000-45-stelliges-digital-multimeter-dmm-7001-teil-12-204350https://de.elv.com/elv-serie-7000-hochspannungs-netzteil-hnt-7000-0-500-v-0-300-ma-204129https://de.elv.com/elv-serie-7000-wechselspannungs-netzteil-wsn-7001-204428They also did some general theory, like this one published after Chernobyl:
https://de.elv.com/radioaktivitaet-entstehung-messung-wirkung-204003Anyway, enjoy!