The buffer power supply unit ZBF-12-4A was built for uninterrupted supply of equipment demanding stabilized voltage 12VDC (10.5 - 13.8 V). Device uses a modern hi efficiency pulse transformer that produces power with high performance (output voltage tolerance + / -1% with ripple and noise of no more than 100m Vp-p). The use of such modern transformer leaves far behind recently used heavy and low performance linear converters. The power supply provides constant voltage to the load by converting AC mains or in the absence thereof, the optional battery. When the mains AC power applied adapter charges the up to 17Ah/12V battery (if installed). The status of the power supply is indicated by LEDs.