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.
This simple source with zener regulation is ideal for experimental projects with operational...
This transmitter was found in an old publication on espionage. It applies a signal of a few...
This circuit drives an old tape recorder when an audio signal is received. The circuit is...