power inverter probelm

Thread Starter

arzelee

Joined Mar 4, 2010
7
I'm having issue with my power inverter trying to get the proper signal but there seem to be a convergence error in multisim which I can't find the problem. I place everything on breadboard and I don't seem to get the right output voltage. The moment the 12v is placed into my circuit things just go wrong but when all the small signal voltage of 5v up to 3904 transistors work flawlessly. I can't seem to find the problem in my work. If you can gear me to the right path of making my project better much appreciated. I was thinking of using fets but I had a load of bjt laying around.
 

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THE_RB

Joined Feb 11, 2008
5,438
Arzelee said:
I'm on a low budget and find this project on a small scale to power some outlet.
I did a quick google for "modified square sine wave inverter" and found a few examples, this one is simpler and more logical than yours as it uses just a 555 timer IC and a 4017 sequencer IC;



It's interesting to see these circuits being called "modified sine wave" now. Decades ago they were called "modified square wave" if my memory is right.
 
If you add in a gate driver such as the TC4422 or similar, getting its power straight from the 12V in, you can use a regular mosfet like the IRF3205/IRFZ44 and such.
 
*facepalm* You dident even bother looking it up so my only suggestion is that you SCRAP this project and just go to your nearest store and just BUY a modified squarewave inverter.

It will end up smaller, cheaper, lighter and way more efficient with way less EMI/RFI interference than anything you could ever build.
 

Thread Starter

arzelee

Joined Mar 4, 2010
7
I end up solving my issue by reducing the noise but working on the fet to get the desired current and I took in consideration with the gate driver. I wasn't sure what you meant when running gate driver to fets so I asked. Buying doesn't solve the problem when I am here to learn. I guess its a bitter world :/
 

THE_RB

Joined Feb 11, 2008
5,438
John Parfrey's circuit in my post uses 8v for the logic ICs, so the gate drive is at either 0v or approx 8v, which should be high enough gate voltage for a lot of modern FETs.

It sounds like most of your problems with building this are related to the amount of power you are aiming for. Maybe you can build a slightly smaller one to get some experience and refine your circuit?
 
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