Relay Clock Generator
For an upcoming project, I need a nice roughly 50% duty cycle relay oscillator, no semiconductors allowed. There are many different designs out there but many just flash (so called “relay flashers”) for a very short time or their timing depends on the attached load.
Luckily I found Pavel Dovgalyuk’s project, which features a nice clock generator. The following schematic is under the Apache License 2.0 and was taken from his project page:
I made two videos showing the clock generator with different capacitor values (110 µF made of two 220 µF in series, and 470 µF) in action. I think they are oddly satisfying to watch.
Also, watch Pavel Dovgalyuk’s video on YouTube: https://youtu.be/uVY6qsk3CsQ
And here’s the finished oscillator with selectable capacitors, power switch and manual pulse button:
