This optical coupler for short distances is powered by 12 V which is the voltage of the lamp and the relay. The circuit can also use emitting LEDs and the phototransistor can be of any type.
This circuit is quite old, from 1964, but can still be mounted with BC558 transistors. The circuit is...
This circuit is from a 1965 General Electric manual. It uses components from the time that admit...
This system of sequential lights for shop windows, discotheques, stores, does not use integrated...