This commercial 6-digit clock circuit was found in August 1976 Radio Electronics magazine. Note the supply voltages and the use of a period module.
This circuit applies to an old dial phone by detecting light pulses in the dial. The circuit is...
This circuit conditions an audio signal, acting as a filter, control, and reaper of signals. The...
Found in old documentation, this timer uses a sensitive relay and a 2N2646. The time is given by...