This circuit was found in the Electronics Experimenter Handbook from 1991. The circuit controls a simple relay for the purpose of turning circuits on or off or switching audio channels.
This circuit is used to obtain the synchronized activation of a mechanical battery clock. The...
ON Semiconductor Phototransistor Output Optocouplers Available from Mouser Electronics is the...
Found in an Electronic Design from the 80's, this circuit monitors a three-phase line, activating a...