5 80W 12-220V simple inverter project

The output of this inverter project is square wave using  600 ohm load  is about 350ma max

Load  must not include equipments with motor that operates in purely sinewave source of 50 or 60 Hz frequency .The circuit is good in lighting like cfls and incandescent lamps. but ensure first that the load must not exceed the 90W for proper operation.

Resistor is four 39ohm 10W  in parallel

transformer is rated  220 to 12-0-12 8A

for more protection, provide 8A fuse and a switch in series to the battery


  1. Dear sir,
    total how many resistor each parallel. is this 2/2 or 4/4 ?
    total resistor is four or eight please clear it.

  2. amit thanks for asking clarification.
    the total number of resistors is 8.
    8 pieces of 39 ohm resistor.4 pieces on every transistors. these resistors are rated 39 ohms 10W

  3. Dear sir , what should be the battery AH for this inverter? and
    i have 12v 9Ah lead acid battery. now what should be the backup time with this battery ?

  4. 12V 9AH battery if fully charged and if the circuit is fully loaded, it can last about 1 hour only...which in this case, it is good only for emergency uses..
    You have to take note also that the inverter is made as simple as possible and good only for non-inductive loads..

  5. sir, here emittor is connected to -ve terminal is it correct sir