We found this circuit for immobilizing a car's ignition system in the December 1976 Radio Electronics magazine. The circuit uses the courtesy light activation switches.
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...