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Micro tesla coil

  1. Mar 6, 2009 #1
    so i found a manual for a small HV device, using a flyback, powered by DC supply.
    here's the link for the http://tacashi.tripod.com/elctrncs/555sstc/555sstc.htm" [Broken]

    i built a small platform giving the primary coil 8V in frequency which in theory should be around 20 KHz(i do not have an osciloscope, but i have a resistor trimmer, so i can scan the frequencies).

    but for some reason, the secondary coil produces very little voltage, it vibrates, and it make a spark at about a milimiter gap, so i know that there is induction going on, but very little.

    i have a suspition that it has to do with the flyback itself, because its of an old screen from 1988 5 inch, monocrome.

    so please do tell me what could be wrong?
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Mar 6, 2009 #2


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    Your link to the "manual" is broken. Also, this borders on dangerous activities per the PF Rules. What is your level of training in high voltage electronics? Why don't you have an oscilloscope and isolation transformer if you are wanting to work with things like this?
    Last edited by a moderator: Apr 24, 2017
  4. Mar 7, 2009 #3
    fixed the link

    well as for the moment im doing my army service, so i pretty much scrap for parts, i dont have access to osciloscope, i have a mere multitester. so no osciloscope for me, though im thinking of making my sound card an osciloscope.

    about HV, i have quite a bit knowledge in physics, and nothing missing in these fields of HV.

    ooh, and it isnt dangerous, its working in realy low currents, thats why i chose this model. the worse it could do is a burned dot on the hand
    Last edited: Mar 7, 2009
  5. Mar 7, 2009 #4


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    Okay, except I need to ask you a Quiz Question before we talk more about high voltage projects...

    Quiz Question -- why is an isolation transformer important when working with AC Mains and HV projects?
  6. Mar 9, 2009 #5
    thats easy, its so the both primary and seconday will have the same ground, so it there happens to be high voltage around, it will be eliminated by both side pulling one against the other.

    but the thing is, that im not using main ac, i chose a small insignificant powerless feeble and unharmful supply of 2 amper max at about 6-12 volts

    i mean, say that i have a transformer of 1/5000 wouldnt the current max at 1/2500 amper?
    Last edited: Mar 9, 2009
  7. Mar 9, 2009 #6


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    So is this what the army teaches you in electronics? An isolation transformer is to ISOLATE. This means that other than being AC it is the equivalent of having a 120 volt battery sitting on your bench. You can grab either terminal and not get zapped as long as there is no current path back to the other terminal.
    Keep in mind that just because you are using a 2 amp source at 6 to 12 volts that you are not necessarily 100% safe. You have a step up transformer and depending on the current capabilities of it, it might pack quite a wallop.
  8. Mar 9, 2009 #7
    hey! the isolation is obvious so i didnt mention it, and why would i need isolation transformer for that reason, i already have isolation quite naturally, i have the flyback, which has about 5 loops on the exposed side of the iron bar, and a dense coil on the other side of the bar, so the connection is only magnetical!
    bah please answer my question.... is the flyback the problematic? or something else?

    and btw, as far as the army is concerned, using a multitester to check APC's and Hammer's batteries, is more than enough!
  9. Mar 9, 2009 #8


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    My Quiz Question referred to isolation transformers and AC Mains connections, to which you incorrectly answered:

    "its so the both primary and seconday will have the same ground, so it there happens to be high voltage around, it will be eliminated by both side pulling one against the other."

    Primary and secondary are isolated in an isolation transformer (hence the name), and that is what worried ASN about your answer. If you do not understand basic safety issues like ground faults and preventing them witih isolation transformers, that calls into question your understanding of how to work with high voltage.

    It's good that you are using a low-voltage power source for your work, so it sounds like that part is reasonably safe. But since you are experimenting with a flyback coil from a small black and white TV, when it's running correctly, it will be generating about 12kV, which could kill you rather easily.

    You say in your originall post (OP) that you are driving the input to the flyback coil with a 20kHz square wave? That's not how flyback circuits and flyback transformers work. I'd point you to articles about how they work, but that might just lead to you getting hurt, which I certainly do not want to have happen.

    It's good that you want to experiment with electronics and build projects -- that's how many of us got started! But starting with a high-voltage project without a much better understanding of the fundamentals, is not a good idea, IMO.

    Maybe start with an opamp project, or something a bit safer?
  10. Mar 9, 2009 #9
    safe is boring =<
    thanks anyway, atleast for the attention
  11. Mar 9, 2009 #10


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    LMAO Ok, comments like this won't get you far on this forum. I'd say it's safe to say you are a candidate for the Darwin Award. Not because I think you are stupid, but because you seem to have the attitude that you are 'above' playing it safe. Of course this could be compared to being stupid, but I'm not going there. Your misunderstanding of the isolation transformer and attempting to sweep it under the rug as if it simply didn't matter tells me me you are reckless and careless. Good luck, I hope you have 9 lives Mr. Cat.
  12. Mar 10, 2009 #11
    but my circut is isolated.... i have a primary on the outside ferrite, and the other, in the the flyback ring, around the ferrite...its isolated!

    and i do understand isolation, i just well overthinked it, thought maybe there is something more to it. continuing current from an induced coil will only happen between the two sides of the wire, since if one side alone is connected to outside body, it will just charge the body by an infinitisiman bit, and then just stop, since the wire itself lessened its own electron pool, and the EMF cannot oppose the new electrical forces. so in order to have contiuing current it must be that: 1. the two electrodes electrically connected(which is relatively safe). 2. one electrode connected to the ground(big metal case) and the other connected to some conducting body(which is dangerous)
    Last edited: Mar 10, 2009
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