help identify some components

Discussion in 'General Electronics Chat' started by lokeycmos, Oct 9, 2011.

  1. lokeycmos

    Thread Starter Active Member

    Apr 3, 2009
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    i came across this schematic on youtube and would like to assemble it. i have a few Q's about what values to use. i emailed the guy but never got a responce. the video and schematic are here:

    http://i433.photobucket.com/albums/qq55/filipkof/obvod.png

    <You tube video removed by Moderator>

    the questions i have:

    1. what transistor did you use to drive the fet?

    2. what fet did you use?

    3. what diode?

    4. how many turns on the flyback?

    5.what is the voltage rating on the 10nF cap?
     
    Last edited by a moderator: Oct 11, 2011
  2. lokeycmos

    Thread Starter Active Member

    Apr 3, 2009
    432
    7
    im thinking using a 2n2222 to drive the fet. i have an extra IRFP250 MOSFET with a 200v rating. its pretty close to the 170v going through it. would this still work? i have a 10nf 250vAC cap. i also have a couple 1000v 1 amp diodes. just wondering if these will work for me? if this works the last unanswered question is how many turns on the flyback? THank you!
     
  3. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    Ohms Law shows that the transistor has a max current of 174mA so a 500mA transistor is fine.
    The Mosfet can be almost any 300V N-channel one.
    The diode is in the wrong location because when the Mosfet is turned off the coil will cause a positive voltage spike that the diode will pass to the Mosfet.
     
  4. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536

    If the power supply is 12V or greater then the BJT is not even needed, though it does serve as an inverter. A 555 can drive a MOSFET directly. You will find parts are not as critical as you think. One of the lessons I learned early from Forrest Mims III is components can have quite a bit of variation and still work.

    Are you trying to build something like this circuit? The arcs shown in the video are deadly.
     
    Last edited: Oct 11, 2011
  5. lokeycmos

    Thread Starter Active Member

    Apr 3, 2009
    432
    7
    what do you mean "inverter"? yeah, im building. check out my youtube channel in my signature. very experienced
     
  6. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    OK, after discussion with the other moderators I'm approving this thread. Keep in mind we do not want to teach how to make a Tesla Coil here, if plans for such are added they will be removed.

    Driver circuitry for Tesla Coils tend to be pretty basic, such as your example. It will be allowed.

    I've said it before, but the BJT does nothing for you, except perhaps to invert the square wave. The critical thing is resonance, the 555 freq must be tuned to match the frequencies of the coil.

    There was a thread my Magnet18 discussing how to find the resonant point in the Projects Forum.
     
    Last edited: Oct 11, 2011
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