Homemade simple home inverter

Photocoupler

Homemade low cost and efficient household inverter

Inverter production, inverter circuit homemade low-cost and high-efficiency household inverter Many household inverter circuits are simple and easy to manufacture, and the efficiency is not high. Some are high-quality and efficient but not easy to make. The inverter described in this paper has simple circuit, low cost, easy maintenance and high efficiency. It can be produced by people with a little hands-on ability. Although it does not have the high-end complex switching power supply integrated circuit of the commercially available high-quality household inverter, the field effect power is amplified, but the effect is not inferior.

This machine is a quasi-sinusoidal output with no-load current less than 450mA, load capacity above 300W, and efficiency above 85%. Usually, powering the electric fan, lighting bulb, electric soldering iron, or a 100W bulb with a cable of 29 inches or less is more than enough (because of the degaussing coil, the starting current is too large, so the string bulb starts, if the degaussing coil is unplugged , the series of bulbs can be used), bringing great convenience to life and maintenance, failure will not cause voltage rise, burned appliances.

I have used it for more than a year and have not seen any problems. The circuit is shown in the drawing. Working principle: After the 12V power supply is turned on, the multivibrator composed of V1, V2, R1-R4, C1, and C2 is electrically oscillated, and the collectors of V1 and V2 are alternately outputting a positive square wave of 50 Hz. After C3 The integral circuit composed of R5, C4 and R6 is integrated into a quasi-sinusoidal wave, and then V3 and V4 are respectively inverted and amplified to respectively excite V5 and V6, so that the final power transistors V7 and V8 are turned on and off in turn, and their collectors Current flows through the transformer primary windings L1, L2 to induce a quasi-sinusoidal high voltage output of approximately 50 Hz on the high voltage side of the transformer. Component selection: Most of the components of this unit can be removed from the used circuit board.

V5, V6 use D880 or C2073. V7 and V8 are respectively connected by three 3DD207 in parallel, and the parameters are 200V/5A/50W, which can also be replaced by 3DDl5D. The adjustable resistor RP can be removed from the old color TV tailgate. There are no special requirements for the remaining resistors and capacitors. The coils L1 and L2 are medium-sized 1.62 mm enameled wires each wound 50 turns. L3, L4, and L5 all use Φ0.53mm enameled wire, and the number of turns is 12, 12, 945. The power tube is equipped with the largest possible heat sink. The machine is equipped with a 150cm wide heat sink. The transformer core is selected to have an effective cross-sectional area of ​​20cm2 or more. The iron core of the used battery charger or the toroidal power transformer core on the power amplifier can be used. The author selects the toroidal transformer core.

Commissioning and commissioning: After all the power tubes are mounted on the heat sink, all the remaining components are soldered to the power tube by scaffolding, without the need to make a circuit board. Since V1, V2 and the components constituting the oscillating circuit may cause the amplitudes of the oscillating signals of the V1 and V2 collector outputs to be inconsistent due to the difference in characteristics, resulting in excessive air consumption, the adjustable resistor RP is used to adjust the balance of the oscillating circuit. The voltage regulator circuit composed of VD and R7 is an essential component to ensure the stable operation of the oscillating circuit, which can solve the problem of imbalance of the oscillating circuit caused by the voltage drop of the battery. When commissioning the test machine, first adjust the RW to the middle position, string the current meter on the 12V power supply end, turn on the power at no load, adjust the RP to minimize the current, and then connect the 60W bulb to the load end; energize and adjust the RP to minimize the current and repeat The no-load load is adjusted several times until the current can no longer be adjusted. At this time, it is close to the transformer and the noise should be the smallest.

If there is no balance, the noise is very loud, and the noise can be heard when the ears are not close. The V5 and V6 emitters are connected in reverse phase with the bases of V7 and V8 through windings L3 and L4, respectively, which can deepen the saturation and cutoff depth of V7 and V8, which is beneficial to improve the efficiency of V7 and V8. Note that the phase of L3 and L4 should be correct. If the connection is wrong, although the high voltage end will have an output, the output voltage is not high and the load capacity will be poor. After debugging, you can find a used computer power supply box. Put the whole machine into it, and use its cooling fan to dissipate heat.