This flip-flop controlled by an LDR-type photocell was found in Radio Electroinics magazine from June 1959. Note that it can be powered from the mains and directly controls a sensitive relay.
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...