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 circuit can function as an output shield for microcontrollers, being compatible with TTL...
This circuit is from a 1979 publication, using displays of 7 segments of common cathode. The...
This circuit is from an English publication of 1982. The bipolar transistor can be a BC548 and the...