This circuit for incandescent lamps was found in the January 1980 Radio Elecronics magazine. The sensitivity can be controlled by a potentiometer and the microphone used is of the dynamic type.
This simple radio was found in a Popular Electronics from the 90s. L1 and L2 have 100 turns on a...
This circuit was found in Radio Electronics magazine from the 90's. The circuit is for small NiCad...
This automotive circuit was obtained from an 80's schematic from the integrated circuit factory...