We found this circuit in an English publication from the 60's. The transistors are of germanium of the time and the headphones must be high impedance magnetic.
The purpose of this circuit is to intermittently start an aquarium air compressor. The intervals...
We found this circuit in an English publication from 1982. The power MOSFET can be of any type and the...
This circuit is from an American 1964 documentation. Transistors of the time are used, but modern...