This circuit was found in the Electronics Experimenter Handbook from 1991. The sensor is a diode and the circuit has a relay according to the voltage used in the supply.
This simple electronic toy organ produces an interesting sound, which can be used by the most...
This SCR circuit was found in an American 1980s documentation. The circuit is still current,...
The sensor of this circuit can be any phototransistor and the SCR can be the TIC106. The circuit and...