power inverter probelm

Discussion in 'The Projects Forum' started by arzelee, Oct 28, 2013.

  1. arzelee

    Thread Starter New Member

    Mar 4, 2010
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    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.
     
  2. Experimentonomen

    Member

    Feb 16, 2011
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    FORGET all about these useless square wave inverters!!! They are barely even usable for lighting.
     
  3. arzelee

    Thread Starter New Member

    Mar 4, 2010
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    well its modified sine wave unless you can make me a cost efficient perfect sine wave..please tell me
     
  4. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    Still can't figure out why people think adding an output transformer to their circuit makes a square wave into a "modified sine wave."
     
  5. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Maybe he meant to say "modified square wave" which I think is the correct term?
     
  6. arzelee

    Thread Starter New Member

    Mar 4, 2010
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    I'm on a low budget and find this project on a small scale to power some outlet.
     
  7. arzelee

    Thread Starter New Member

    Mar 4, 2010
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    If I was able to make a sine wave with no budget limit I would. I need some help with this :/
     
  8. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    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;

    [​IMG]

    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.
     
  9. arzelee

    Thread Starter New Member

    Mar 4, 2010
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    sadly I can't find that type of mosfets within my reach or is a different cross part number which I can use.
     
  10. Experimentonomen

    Member

    Feb 16, 2011
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    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.
     
  11. arzelee

    Thread Starter New Member

    Mar 4, 2010
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    I'll see what I can use but can you explain gate driver? from what I understand I'll be having 4 fets to run this?
     
  12. Experimentonomen

    Member

    Feb 16, 2011
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    *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.
     
    shortbus likes this.
  13. arzelee

    Thread Starter New Member

    Mar 4, 2010
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    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 :/
     
  14. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    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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