Found in a Popular Electronics from the 90s, this circuit applies to flashes with xenon lamps. The transistor admits equivalent and the phototransistor is of the Darlington type.
This detector uses an unusual sensor today. The circuit is from an 80s documentation. Its...
This circuit was found in the December 1976 issue of Radio Electronics magazine. The circuit...
For inductive loads we have the configuration shown in the figure. Note that the opto-coupler...