This circuit was found in General Electric documentation from 1968. The circuit uses triac from the time as well as transistors that can be replaced by modern equivalents.
In the figure we have a sensor circuit that makes use of common transistors and a photo diode as...
This unusual configuration, but which has already been explored in other articles, uses diodes in the...
This circuit uses a modulated signal from a PLL 567 to operate safely with an infrared emitter. The...