We found this circuit in the July 1969 Radio Electronics magazine. The circuit uses a coupler made with a lamp and an LDR. The power of the lamp determines the types of diodes.
This circuit for incandescent lamps was found in a 70s documentation. The circuit uses an SCR...
This circuit is from an Elementary Electronics from 1977. It can be assembled with relative ease...
This circuit detects the presence of strong signals from spy transmitters, enabling their...