Small -size power adapter

The utility model discloses a small -size power adapter, including transformer T1, rectifier bridge Q, transformer T2, resistance R1, electric capacity C1, chip U1 and opto -coupler U2, electric capacity C1 one end is connecting resistance R1 respectively, transformer T2 coil L4 and 220V alternating current one end, the electric capacity C1 other end is connected respectively to the 220V alternating current other end, the resistance R1 other end and transformer T2 coil L5, rectifier bridge Q pin 1 is connected to the transformer T2 coil L4 other end, the transformer T2 coil L5 other end is connected to rectifier bridge Q pin 4, 3 ground connection of rectifier bridge Q pin, grounded capacitance C2 is connected respectively to rectifier bridge Q pin 2, resistance R3, resistance R5, electric capacity C3, resistance R6 and transformer T1 coil L2. The utility model discloses small -size power adapter circuit structure is simple, and small, with low costs, the interference killing feature is strong, can change output voltage through the intrinsic standoff ratio that changes R9, R10 and R11, can the various power equipment of adaptation, and especially adapted using widely.