Working principle of electronic transformer - Power Circuit - Circuit Diagram - Huaqiang Electronic Network

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

Industrial Router Crystal 3.2*2.5mm 3225 26M (26.000MHZ) 12PF 10PPM 20PPM 30PPM

Brand AVX TPSE226M035R0125 Low impedance tantalum capacitor AVX 22

MOS power IC full range

Photocoupler

The electronic transformer described below has an input of AC220V, an output of AC12V, and a power of up to 50W. It is mainly a transformer circuit developed on the basis of high-frequency electronic ballast circuit. Its performance is stable, small in size and large in power, thus overcoming the shortcomings of traditional silicon steel sheet transformers, such as large size, heavy weight and high price.

The circuit is as shown. The working principle is similar to that of the switching power supply. The diodes VD1 to VD4 form a rectifier bridge to convert the mains into direct current. The high-frequency oscillating circuit consisting of the oscillating transformer T1 and the triodes VT1 and VT2 converts the pulsating DC into a high-frequency current, and then the iron. The oxygen output transformer T2 steps down the high frequency and high voltage pulses to obtain the required voltage and power. R1 is a current limiting resistor. The resistor R2, the capacitor C1 and the bidirectional trigger diode VD5 constitute a start trigger circuit. The triode VT1 and VT2 are selected as S13005, and the B is 15 to 20 times. High-power triodes such as C3093 and other BUceo>=35OV can also be used. The trigger diode VD5 selects DB3 or VR60 of about 32V. The oscillating transformer can be self-made and wound on the magnetic ring of the H7X10X6 with an audio cable. TIa, T1b around 3 turns, Tc around 1 turn. The ferrite output transformer T2 also needs to be self-made, and the core is an EI type ferrite having a side length of 27 mm, a width of 20 mm, and a thickness of 10 mm. T2a is wound with a diameter of 0.45 mm and a high-strength enamelled wire around 100 匝, and T2b is wound with a diameter of 1.25 mm and a high-strength enameled wire. Diodes VD1 ~ VD4 select IN4007 type, bidirectional trigger diodes use DB3 type, capacitors C1 ~ C3 use polypropylene polypropylene polyester capacitors, withstand voltage 250V.

When the circuit is working, the working voltage at point A is about 12V; the point B is about 25V; the point C is about 105V; the point D is about 10V. If the voltage does not meet the above values, or the circuit does not oscillate, check the circuit for mis-welding, missing soldering or soldering. Then check if VT1 and VT2 are good, and whether the phases of T1a and T1b are correct. After the entire circuit is successfully adjusted, it can be placed in a small box made of metal material, which is beneficial for shielding and heat dissipation, but must pay attention to the insulation between the circuit and the outer casing. In addition, changing the number of turns of the T2a and b coils can change the high frequency voltage of the output.