12-220V 50Hz Power Inverter

[johnnyblaz]

Hi there. I was going through this inverter circuit and I couldn't fully understand the circuit. As far as i figured out the CD4047 is used to generate the  50Hz PWM/square wave signal and the transformer is used to step up the voltage to 220V but what is the purpose of the LM324 ICs and 2N3055 & C1061 transistors? Any help would be appreciated. Thanks 

[David Hess]

That is a very poor design.

The LM324 is being used to buffer the output of the clock generator while providing current limiting.  2N3055, C1061, and then a pair of paralleled 2N3055s are configured as a three stage darlington transistor to get enough current gain.

Problems with this circuit include high dropout of the triple darlington configuration causing excessive heating and low efficiency, overlap of the output clock causing excessive shoot-through current, and poor current sharing of the paralleled output transistors.

[johnnyblaz]

I really appreciate your help. Any suggestions on how to improve this design?
Please include component/ic number for the new design.

[Seekonk]

Get an EG0002 board and a couple fet and you are done for a couple bucks and you have sine wave.

[james_s]

That looks like it would have been a reasonable design for the 1980s, but these days inverters all use a high frequency DC-DC section followed by a chopper or PWM sine generator, it's a lot more efficient.

[Audioguru]

Does anybody make or use a squarewave inverter anymore?
The circuit shown was a 500W squarewave inverter at www.electyronics-lab.com and it s original horrible design did not work. The circuit you found also does not work because the R and C for the CD4047 are wrong.

I corrected the RC on the CD4047 and made a few more improvements about 13 years ago and many of these simple inverters were made and used. The circuit was built with common cheap parts in the Philippines and used by poor people who had no electricity. A battery boy picked up the discharged 12V batteries and replaced them with charged ones every few days.

 

[james_s]

Most of the inexpensive inverters now produce a "modified sine wave" which is really just a square wave with some dead time inserted. The better ones put out a true sine wave but those are still relatively expensive compared to the common modified sine type.