This circuit was originally suggested in a 1968 publication to generate a white mark (frame) on a film at regular intervals to serve as a time reference.
This receiver for an audio link by modulated light was found in a 90s Elektor. Transistors are common...
Using a tunnel diode, this circuit was found in a 1966 American publication. The circuit is for...
This interesting configuration of optical triggering using an oscillator was found in a 90s...