Electronic transformer circuit

The electronic transformer introduced in this article overcomes the shortcomings of traditional silicon steel sheet transformers such as large size, weight, low efficiency, and high price. It has mature circuits and stable performance. 　　

working principle  　　

The working principle of this electronic transformer is similar to that of a switching power supply. The circuit schematic diagram is shown in Figure 1. VD1-VD4 rectifies the mains power into DC, and then converts the DC into a high-frequency current of tens of kilohertz, and then uses a ferrite transformer to Frequency and high voltage pulse step-down. In the figure, R2, C1 and VD5 are the start trigger circuit. C2, C3, L1, L2, L3, VT1, and VT2 constitute the high-frequency oscillation part. The component selection and production component list is shown in the table below. No. Name Model Quantity R1 Resistor 1Ω/1W 1 R2 Resistor 200K 1 C1 Polyester capacitor 0.01u/100V 1 C2, C3 Polyester capacitor 1000P/1kV 2 C4, C5 Polyester capacitor 0.47u/250V 2 VD1－VD4 Rectifier diode IN4007 4 VD5 trigger Diode 32V 1 VT1, VT2 Transistor C3039 2 L1, L2, L3 (in one) For the oscillation transformer, see the text 1 after the table. For the high-frequency transformer, see the text 1 after the table. L1, L2, and L3 are wound around H7×4×2mm3 respectively. On the magnetic ring, L1 and L2 are wound with 6 turns; L2 is wound with 1 turn. L4 and L5 are wound on the H31×18×7mm3 magnetic ring. L4 is wound with 340 turns of high-strength wire with Φ=0.1mm; L5 is wound with 20 turns of high-strength wire with Φ=1.45mm. VT1 and VT2 use high-power silicon tubes with voltage resistance BVceo≥350V. There are no special requirements for other components. When the circuit is working normally, the working voltage of point A is about 215V, point B is about 108V, point C is about 10V, and point D is about 25V. If it does not oscillate, check whether the phases of VT1, VT2 and L1, L2, and L3 are normal (just swap the two wires of L3). Changing the number of turns of L5 changes the output voltage.