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.
We found this circuit in a 1970 publication by General Electric. The components can be changed...
This source is used to supply circuits with operational amplifiers, being originally created for...
Suggested by American documentation from 1968, this circuit divides the frequency of synchronized...