This circuit is from an American 1964 documentation. Transistors of the time are used, but modern equivalents can be employed.
The circuit that gave rise to this configuration was found in a magazine of the 1980s with the...
The interruption of the light incident on the phototransistor causes the trip of this circuit that can...
March 2017 - Texas Instruments' new TPS2H160-Q1 smart switches can now be obtained from Mouser...