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 a 1966 documentation, this “coin finder” uses components from the era operating at 2.1...
This filter operates in the “opposite” way to the previous one (CIR8814), cutting all signals...
In the figure we have the way to use a stepper motor as an encoder. Operational amplifiers can be of...