The power supply unit has been desi

The power supply unit has been designed with two integrated circuits LM317T.
The trimmer potentiometer is used to control the output voltage (10 to 14V). In case of use of a battery, the output voltage is set to 13,6V to allow for re-charge of the battery. In case that the input voltage is cut, the battery is on.
The power supply unit is suitable for powering of alarm systems and other devices that must be in continuous operation even in case of power mains failure.