Cebek FE-121 module is a single rail 5VDC stabilized power supply. It can deliver a maximum of 1A, the output is fully regulated and short circuit protected. A PCB mounted pre-set potentiometer is supplied to adjust the output voltage (3 - 8VDC), to allow for long cable runs and supply voltage variations. The FE-121 module has a small enclosed transformer mounted on the circuit board. and LED to indicate its operating.