We found this solid-state relay circuit that can function as a shield in a Radio Electronics magazine from December 1989. The optocoupler is a phototransistor type.
This circuit was found in a 1964 documentation. It shows how to achieve automatic gain control for...
Using transistors at the time, this circuit was found in a 1967 Ferranti documentation. The...
This circuit, which controls both the temperature and the level of a liquid in a reservoir, was...