Uninterruptible power supply provides output power to 220 watts (load current up to 1A). In the mode switch SB1 12/220 – the battery voltage is applied to a given multivibrator Q3 Q4 50 Hz, which builds up powerful keys Q1, Q6, amplified and fed to transformer T1. With the secondary winding T1 voltage of 220 V and 50 Hz filters L1 C1 C2 goes to the load.
When switching to the position SB1 220/12 exciter is turned off and the mains socket with a filter HR1 L1 C1 C2 comes to the winding of the transformer T1 and I through the diodes D2, D3 charges the battery current to 6A. As a T1 can apply any power transformer with two secondary windings, which provide 10 / 10A, L1 contains 2 x 10 turns of PEL to 0.8 ferrite ring K28 * 16 * 9 M2000NM. Q1, Q6, D2, D3 are fixed through the insulating mica seals for total radiator area of 200 cm ².