This is the transistored power inverter circuit diagram, capable to handle up to 500W output loads. The circuit built based 50Hz square wave generator 4047 and square wave signal amplifier based power transistor 2N3055.
Calculating the transformer rating:
The basic formula is P=VI and between input output of the transformer we have Power input = Power output
For example if we want a 220W output at 220V then we need 1A at the output. Then at the input we must have at least 18.3V at 12V because: 12V*18.3 = 220v*1
So you have to wind the step up transformer 12v to 220v but input winding must be capable to bear 20A.
Transistored Power Inverter 500W