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.
In the figure we have the simple way to implement a voltage reference with an operational one. The...
Found in a Popular Electronics from 1992, this circuit has two output voltages given by the...
This circuit allows the testing of integrated circuits of type 741 (operational amplifier) such as...