We found this circuit in the January 1979 issue of Radio Electronics magazine. Components are still common today, with the 7106 display driver standing out.
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...