1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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 ...

    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 .


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


    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' .....


    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 ?


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

    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.
    Last edited: Mar 30, 2013
  4. Mar 31, 2013 #3


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    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.
    It dumps the capacitor across a thin piece of wire and ignites the gunpowder quite nicely.

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


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    If you get it working you could get the trigatron to take it's own picture.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook