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 control circuit for incandescent lamps was found in a publication from the 90s. The circuit uses...
The power supply for this circuit must be symmetrical at 12 + 12 V and the load must be 8 ohms. The...
This practical two-transistor linear motor control idea was found in the September 1962 Radio...