High Voltage - Electric Fly Swat

Discussion in 'General Electronics Chat' started by erlend, Mar 6, 2008.

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  1. erlend

    Thread Starter Member

    Feb 8, 2008
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    I opened my electric fly swatter to see how it worked. I was curious about how it could convert 3VDC (2*D batteries) into the quoted 1500V.

    What I see is a capacitor (400nF) at the end, and a voltage multiplier (Villard I think - 4 diodes and 4 capacitors) and then a *something*... labelled Q1. What is that component, is it like a miniature flyback?

    Thanks.
     
  2. thingmaker3

    Retired Moderator

    May 16, 2005
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    Q1 is probably some kind of oscillator or inverter. The Villard cascade (aka Cockroft-Walton multiplier) must have an AC input.
     
  3. beenthere

    Retired Moderator

    Apr 20, 2004
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    Q is a conventional designator for transistors/FET's. Something has to turn current on and off the make an artificial AC for the voltage multiplier. Unless there's a transformer in there, the voltage isn't going to be more than a bit below 15.
     
  4. erlend

    Thread Starter Member

    Feb 8, 2008
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    Well it looks like something with copper coils round it. The output from the flyswat it definitely around 1500V - it makes a big spark and I measured it (as best I could).
     
  5. mrmeval

    Distinguished Member

    Jun 30, 2006
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  6. erlend

    Thread Starter Member

    Feb 8, 2008
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    Here's some photographs of the diagram, for those interested.
     
  7. erlend

    Thread Starter Member

    Feb 8, 2008
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    I can't understand how this circuit actually works... the thing which looked like a Villard Multiplier isn't one (as far as I can see). I just don't get what it is though. I've attached the circuit diagram, would someone mind please telling me how on Earth this thing works?

    Thanks.
     
  8. Xray

    Well-Known Member

    Nov 21, 2004
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    It looks to me like a simple oscillator circuit that uses the transformer for the feedback, and also to step up the voltage and provide a high frequency AC waveform which feeds a C.W. voltage multiplier circuit consisting of a few diodes and capacitors. Very basic but effective circuit. I'm sure that the flies would agree!
     
  9. erlend

    Thread Starter Member

    Feb 8, 2008
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    The C.W. multiplier is the same as a Villard multiplier, right? In that case the multiplier in the circuit is *not* a C.W. ... it's something strange (see attached diagram).

    As for the transformer - I have read elsewhere that it is a "blocking oscillator", though the workings of these are difficult for me to understand.
     
  10. Kick-bak-au

    New Member

    Nov 21, 2009
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    Maybe a modified 'Joule Thief' circuit could work ?

    Thanks for drawing the zapper circuit as i'm about to try and make one
    myself. The step up transformer or whatever it is will be the hard part me thinks :confused:

    Kick-bak
     
  11. BMorse

    Senior Member

    Sep 26, 2009
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    I have built several voltage doubler circuits that put out well over 2K :eek: using a couple of D cell batteries.... I have just recently "improved" on it 4 AA batteries and I am getting over 3.5K!! Basically made it to prove a point to one of my employees.... He had "graduated" from a tech school and since I learned everything myself (self taught in all aspects) he always wants to challenge me on making something.... so one day he was saying that he could handle a shock from a Tazer (He was previously employed as a security guard so he had to undergo "shock" theraphy from a Tazer to "know what it feels like to be tazed") anyway he said I could NOT make anything that was powered by AA batteries that would shock him more than the Tazer.... so I went on to build this hideous contraption to prove a point... well needless to say, after he picked himself up off the floor after grabbing the exposed contact points... he said I succeeded in proving him wrong once again :D....

    Oh, and he was also dumb enough to be talked into actually touching one of those fly swatters also..... I believe he said there was a definite difference with my High Voltage DC Dazer, and the high voltage AC fly swater :D (You can get them cheap at Harbor Freight, I bought one for my 11 year old for $4.99, bugs scream when they see him coming :eek:!!).....

    P.S.

    My circuit is based around an NE555 Timer, a IRF640, and an Audio Transformer( 8ohm / 1000ohm ), which the output is routed through a voltage doubler circuit built around some 1n4007 Diodes and some 400Volt, .1uf caps....



    My .02
     
    Last edited: Nov 21, 2009
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  12. PackratKing

    Well-Known Member

    Jul 13, 2008
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    It is a simple version of the voltage multiplier / oscillator circuit in an electronic flash unit. Those employ a pair of transistors, driven by a flyback transformer. Many different versions of this circuitry will work. It also may serv to explain the ascending whine heard as an electronic flash charges up.

    Lots of interesting and also extremely deadly applications possible here.
     
  13. Audioguru

    New Member

    Dec 20, 2007
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    There are many simple "stun gun" circuits on the web that use a transistor oscillator driving a little audio transformer like the one shown to step up the voltage.

    Little audio transformers are hard to find today. My 1958 AM portable radio had one.
     
    Last edited by a moderator: Oct 29, 2011
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