This power supply protection circuit was found in the December 1978 Radio Electronics magazine. The SCR is triggered by shortening the power supply and quickly blowing the protection fuse.
In the figure we have the way to use a stepper motor as an encoder. Operational amplifiers can be of...
Placed inside the refrigerator, this circuit triggers an oscillator when the part is opened...
We found this circuit in an old documentation from the 70s, but it can be assembled with more...