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Solid State Tesla Coil Burning Mosfets

Discussion in 'General Electronics Chat' started by Nissan20det, May 24, 2017.

  1. Nissan20det

    Nissan20det Member

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    well I get a decent signal at my gate. nothing that resembles the GDT primary.
    so that sag is only shown at the output of driver chips/ GDT Primary

    I'm not sure what you meant by this. Right now I am re wrapping my GDT with less windings and a much thicker wire as the primary same Cat5e cable as secondary on GDT.

    You were saying something may just do the trick, what where you talking about doing?
     
  2. Mosaic

    Mosaic Well-Known Member

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    I don't understand....where is the sag? If there is no SAG at the IGBT gates then u don't have a problem with the switching.
     
  3. Mosaic

    Mosaic Well-Known Member

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    Here is my 'pulse' driver and pulse board.
    The off white colored gate drive comes off the smt MCP1407 driver, 8 pin IC, goes thru a pair of ferrite bea ds and then thru a couple paralleled SMT ceramic caps then splits thru 3, 5 ohm Gate damping (thru hole) resistors and then finally into the gate pads of the IRF3205 totaling over 400nC of gate charge.
    PulseBRD TOP.png
     
  4. dave

    Dave New Member

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  5. Mosaic

    Mosaic Well-Known Member

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    BTW, Have a look at this:
    http://richieburnett.co.uk/hfsstc.html
     
  6. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    Apparently Mosaic wants to take over this discussion. Guess I'm out then.
     
  7. Mosaic

    Mosaic Well-Known Member

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    Whatever gave you that impression?
     
  8. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    I was trying to keep it structured in such a way as to maintain a clear path forward, but when three people are talking back and forth it's impossible to keep on track. If you want to take over that's fine with me, I'm not complaining. I just can't maintain structure this way. Not to mention you keep repeating things I've already said.
     
  9. Nissan20det

    Nissan20det Member

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    Ya anyway, I did beef up my GDT primary gauge from cat5e to 18 gauge, then changed my GDT winding ratio to 6-8.5. As well added solder to the gate output traces it didnt change my waveform but not by much. Im not sure if its good or bad.
    20171026200227.png GDT primary
    20171026200518.png At Gate


    DerStorm8 Please continue I was just trying any suggestions, was here working on this all day, so was just trying stuff. Just so ur not confused

    GDT is now 6-8.5 turns, 18gauge as primary cat5e as secondary.

    Current circuit bellow/ Only added those 10uf caps to schematic, they where on my board already.
     

    Attached Files:

  10. Mosaic

    Mosaic Well-Known Member

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    If the waveform is good at the gate then the transistor is happy.
    Maybe what you're seeing at the primary of the GDT is ground loop interference on your scope probe.
    Move the scope ground wire around and see if it changes the trace.
     
  11. Mosaic

    Mosaic Well-Known Member

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    Didn't realise a forum thread was limited to a 2 person conversation.
     
  12. Nissan20det

    Nissan20det Member

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    Could a weak power supply cause the driver to heat up? My driver supply is a 12v 1 amp wall transformer, reads about 14.7vrms definitely reads high for it's sticker.. I tested my drivers current draw and it's never above .5/.6 amp usually. So I figured I was okay there. But since there 9 amp drivers I'm confused how there heating up when I can't even supply over 1 amp


    Just another thought
     
  13. Nissan20det

    Nissan20det Member

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    I didnt lose you did I Derstorm?
     
  14. Nissan20det

    Nissan20det Member

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    Derstorm, Whats next?
     
  15. Mosaic

    Mosaic Well-Known Member

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  16. Nissan20det

    Nissan20det Member

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    Yeah that's pretty sweet, is that very much they already made CT for input? With those be used for secondary feedback or primary feedback? I never really understood primary feedback, it seems quite a bit more difficult than using your secondary.
     

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