Hi!

In this instructable you are going to learn how to make an inverter with just two power transistors and two resistors.

The Transformer and the battery used in this project are from an old UPS (uninterrupted power supply).

The power rating of this inverter is around 70 watts & the output frequency is 51.1 Hertz.The AC output waveform is square wave with a maximum step-up voltage of 250 volts AC.

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Step 1: Stuff Needed:

2 x MJE13009 NPN power transistors.
2 x 1 kilo ohm , 1 watt resistors.
1 breadboard.
some wires
2 aluminium heatsink.
one single phase Centre tap transformer.
1 x 12 volts battery.
one bulb holder.
one load bulb.
productive gloves.

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Step 2: The Switching Circuit & the Transformer:

Now what you have to do is connect the collector terminal of the power transistor to the base terminal of the

other power transistor with the help of the 1 kilo ohm resistor.

Similarly, you have to connect the collector of the other power transistor to the base of the first power transistor with the help of the one 1 k-ohm resistor.

Now take two wires and connect them to the collector terminals of both the power transistors.After this, you have to connect these two collector wires to the two input terminals of the transformer leaving the middle one open.

Positive battery input will be connected to this middle terminal of the transformer.

Now take one wire and connect its emitter terminals of both the power transistor.Now connect 1 wire as a

common wire for both the emitter terminals to the power transistor.

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Step 3: Battery Connections and Testing:

Now take a CFL or an LED bulb and connected it to the output terminals of the transformer.

You are now left with just two wires.One is the common emitter output and the other is the center Tap wire of the transformer.The centre tap wire will be connected to the positive terminal of the battery while the common emitter terminal will be connected to the negative terminal of the battery.

After this full connection you should see your connected load bulb glow brightly.

Please don't forget to watch the full video provided at the top of the instructable for complete understanding.

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Thank You!