This optically coupled circuit was found in the February 1968 Radio Electronics magazine. The circuit uses an LDR in modulation. Transistors are types of the time.
Found in old American documentation, this circuit demodulates signals from 1 kHz to 10 kHz for...
This simple circuit is a continuity test that, in addition to testing resistors, can also test...
This circuit was obtained from an English magazine from 1985. It consists of a pulser that drives...