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 was found in an old publication and can be adapted for use with modern...
The circuit presented generates pulses at regular intervals with the duration controlled by a...
The LS150 is an uncommon high-performance operational amplifier today. The circuit is from old...