Inverter Diagram:

The Q1 and Q2 used generate square wave. Q5-Q8 amplify the signal and the transformer to increase the AC/square wave current from 12VAC to 220V AC 50HZ.

Inverter PCB layout:

The following image is the bottom/copper PCB layout and to layout for the components placement. You may use universal PCB veroboard to make it easier.

This document will show you the basic theory of DC to AC inverters, about the circuit’s works, the calculation to build DC to AC inverter and more. The sample of inverter circuit diagram also included in this document.

INTRODUCTION

Transistor dc to ac inverters are useful in a wide variety of applications. They power the complicated electronic systems of orbiting satellites and cool astronaut’s suits. They are widely used to operate gyros and other airborne instruments. They provide AC power to operate the electric shaver in your car. Inverters may become increasingly important and widely used with the further development of economic low voltage DC power sources such as solar cells, nuclear cells, fuel cells, etc.

It should be noted that rectifications of the inverter output results in DC to DC convertion. Transistor inverters as described here in are, therefore, the “heart” of transistor DC to DC converters. However, when used as converter, to provide rectified output the frequency and waveshape of the transistor circuit are unimportant, except as they relate to the efficienty and smoothing of the rectified output.

Download the document of Basic Theory of DC to AC Inverters:

The ABC's of DC to AC Inverters

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Schematic diagram:

PCB layout and component placement:

Since this circuit has lethal potential and high risk, please be careful when try this circuit. It’s need more experience to build this 300W power inverter circuit.

Basic Inverter Components list:

Notes:

1. Q1 and Q2, as well as T1, determine how much wattage the inverter can supply. With Q1,Q2=2N3055 and T1= 15 A, the inverter can supply about 300 watts. Larger transformers and more powerful transistors can be substituted for T1, Q1 and Q2 for more power.

2. The easiest and least expensive way to get a large T1 is to re-wind an old microwave transformer. These transformers are rated at about 1KW and are perfect. Go to a local TV repair shop and dig through the dumpster until you get the largest microwave you can find. The bigger the microwave the bigger transformer. Remove the transformer, being careful not to touch the large high voltage capacitor that might still be charged. If you want, you can test the transformer, but they are usually still good. Now, remove the old 2000 V secondary, being careful not to damage the primary. Leave the primary in tact. Now, wind on 12 turns of wire, twist a loop (center tap), and wind on 12 more turns. The guage of the wire will depend on how much current you plan to have the transformer supply. Enamel covered magnet wire works great for this. Now secure the windings with tape. Thats all there is to it. Remember to use high current transistors for Q1 and Q2. The 2N3055’s in the parts list can only handle 15 amps each.

3. Remember, when operating at high wattages, this circuit draws huge amounts of current. Don’t let your battery go dead :-).

4. Since this basic inverter project produces 120 VAC, you must include a fuse and build the project in a case.

5. You must use tantalum capacitors for C1 and C2. Regular electrolytics will overheat and explode. And yes, 68uF is the correct value. There are no substitutions.

6. This circuit can be tricky to get going. Differences in transformers, transistors, parts substitutions or anything else not on this page may cause it to not function.