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 configuration (using a logic gate with TTL compatible output) uses an amplifier transistor to obtain...
In addition to the didactic purpose, the figure circuit can also be automated. In this case, the...
The maximum time interval of this circuit depends on C1. Larger values can be used to get closer to...