This circuit was found in the September 1997 issue of Electronics Now magazine. The circuit is for low impedance headphones powered by two batteries.
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...