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Perfecting a spark gap switch - help needed

  1. Mar 19, 2012 #1
    Hi everyone , this is my first post here :) . I am an auto electrician , my hobby is photography. I am interested in high speed photography and have invented a new form of photography in a way . I call it 'superspeed photography' . It involves taking a picture of something that is triggered by the act of taking the picture .
    My early attempt involved a water balloon being burst by a needle pushed into it by a solenoid in series with the flash capacitor ...
    aaaDSC_0439.jpg

    Now I am busy building a spark-gap switch or 'trigatron' as I am told it is called .
    It is proving difficult to get reliability . With the first design I drilled a hole in the conductor and ran an insulated wire down the middle so that when I take a picture my camera flash triggers a 40 000 volt spark down the centre of the contacts and causes the 320 volt capacitor to jump the gap through the ionized air .

    zDSCF0009.jpg

    It blew a 10 amp and a 20 amp fuse on two of my attempts ....

    aDSCF0023.jpg

    a 40 amp fuse caused the electrode tip to blow off rather and it is proving difficult to get a reliable switch each time .
    This is a 3.5 amp fuse blowing with 320 volts photographed at 1/1000th sec - the act of pressing the shutter is what triggers the spark and 'explosion' .....

    zDSC_0002.jpg

    Tonight I tried a different version based on some pictures I have seen of a trigatron - it isn't switching though the contacts should last much longer this time if I get it to work ....
    I've put some light bulbs in series with the switch to quieten the noise of fuses blowing in my garage though I'm wondering if they just can't light up fast enough for the quick switching action I would get ?
    aP1040290.jpg

    aP1040291.jpg

    Any advice on perfecting this design for reliable switching and hopefully some really good photos would be appreciated :)
    zsparks018.jpg

    Thanks , Desmond .
     
  2. jcsd
  3. Mar 30, 2013 #2
    1100 views and no replies yet? Does anyone have any answers for me?
    here's my last design.
    aaatrigatron_zpsf9e47ce3.jpg
     
    Last edited: Mar 30, 2013
  4. Mar 31, 2013 #3

    CWatters

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    I would probably have used the hot shoe switch directly rather than the current through the flash capacitor. Then the rest is electronics and depends on what exacty you are trying to trigger. Perhaps use an opto isolator to fire a triac or something.

    PS: Make the Triac easy to replace if you are trying to pop fuses with unlimited current.
     
    Last edited: Mar 31, 2013
  5. Mar 31, 2013 #4
    I eventually wired up an SCR to the hotshoe trigger circuit, the one I'm using is rated at 800volts and 3800 amps surge.
    aaDSC_0005.jpg
    aaaDSC_0171_zpsf89874dd.jpg
    It dumps the capacitor across a thin piece of wire and ignites the gunpowder quite nicely.
    aDSC_0016-1.jpg

    However, I would still like to perfect the Trigatron just for fun:)
     
  6. Mar 31, 2013 #5

    CWatters

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    If you get it working you could get the trigatron to take it's own picture.
     
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