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 power supply, found in an Argentine publication from the 1970s, uses a wire potentiometer of 25 W or more...
We found this circuit in a publication from 1966. The components are from the period. Complete...
Found in an 80's documentation this circuit uses an integrated from the uncommon era today. Other...