Input: AC220V

Output: AC12V

Power: 50W

      It is a transformer circuit researched and developed based on high frequency electric ballast circuit. It is stable, small, powerful, and get over the shortcoming of tradition silicon steel slice, which is big, heavy and expensive.

     Circuit is as shown. The functioning theory is similar to switch power, diode VD1 ～ VD4 compose commutate bridge and turn mains supply into DC, and high frequency surge circuit, which consist of surge transformer T1, audion VT1, VT2, turn pulse DC into high frequency current, then ferrite output transformer T2 step-down high frequency high voltage pulse, thus obtain the right voltage and power. R1 is current limiting resistor. Resistance C2, capacitance C1 and bidirectional trigger diode VD5 formed a startup a trigger circuit. Audions VT1 、 VT2 choose S13005, the B is 15 ～ 20 times. You may use C3093, which is powerful dynatron with BUceo>=35OV. Trigger diode VD5 choose DB3 or VR60, which has around 32V power. Surge transformer can be made by yourself, coil H7 X 10 X 6 magnetic ring with audio wire, T1a 、 T1b coil 3 circles, Tc coil one circle. Ferrite output transformer also can be made by yourself. The magnetic core should use 27mm long, 20mm wide, 10mm thick EI ferrite. T2a use 0.45mm high strength enameled wire to coil 100 circles, T2b use 1.25mm high strength enameled wire coil 8 circles. Diode VD1 ～ VD4 should use IN4007, bi-directional trigger diode should use DB3 type. Capacitance C1 ～ C3 should use modacrylic polyester terylene capacitance, 250 voltage resisting.

      When the circuit is functioning, voltage in A point is about 12V, voltage of B point is around 25V, C point is around 105V, D point is about 10V. If voltage cannot meet above values, or the circuit do not surge, please check if there is any mistake welding, miss welding point or fake welding. Then check if VT1 and VT2 is ok, if the phase of T1a 、 T1b is correct. After the whole circuit is debugged successfully, place it in metal box for screening and radiating, but please be notice that the circuit should be insolated with the shell. In addition, change the number of T2 a, b loop can change the output high frequency voltage.