HV circuits

Discussion in 'General Electronics Chat' started by eman12, Apr 25, 2008.

  1. eman12

    Thread Starter Active Member

    Oct 26, 2007
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    Hi there,

    I just have made these 2 high voltage circuits for a 'capacitor lifter'

    the first circuit uses one 2N3055 and that's what I have made first,
    but my lifter just started to rings(movetion) in the ground and did not liff off.
    so I thought mybe the power is not enough so I went for the second circuit which uses 2 2N3055 transistor as push pull. but the output power seems to be lower than the first circuit.

    both circuits have a cascade diode at the output of the HV transformer so I thought mabe the first circuit is working in the half cycle and is good for the cascade diode. is that true?

    What is your ideas about the amp draw of both circuits? my regulated poer supply is a 0 to 30V, 5A

    thanks in advance

    P.s, both circuits are from here:
    http://www.powerlabs.org/flybackdriver.htm#INTRODUCTION:

    http://www.kronjaeger.com/hv/hv/src/fly/index.html
     
  2. eman12

    Thread Starter Active Member

    Oct 26, 2007
    41
    0
    besides how this circuit can be a push pull circuit?
     
  3. SgtWookie

    Expert

    Jul 17, 2007
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    Well, the 1st circuit looks like a modified Hartley oscillator - without the tank capacitor. Perhaps the author was relying upon the coil capacitance to act as a tank?

    Did you wind your own transformer, or did you pick up one somewhere?
     
  4. eman12

    Thread Starter Active Member

    Oct 26, 2007
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    well for the first pic, the primary is wound by me, 5 turns 1mm for the collector and 3 to 4 turns 0.5mm for the baseand the second pic has the above be doubled and center taped.
     
  5. SgtWookie

    Expert

    Jul 17, 2007
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    Take a look at Ronald's "Flyback Converters for Dummies" page.
    http://www.dos4ever.com/flyback/flyback.html

    It's not really "for dummies" (Ronald has a sense of humor) - it's a very nicely written page.

    I don't know how much output voltage you're looking for, but this is one good way to do it. Ron did a great job of explaining just how to calculate and test things to get decent performance.
     
  6. Wendy

    Moderator

    Mar 24, 2008
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    If you're designing a lifter as I understand it you'll need several KV, and 15KV isn't too much (pulsating DC). I thought seriously about trying something like this at one time, so will be following it with interest.

    For those who aren't familiar with them lifters generate thrust using no moving parts. Are we talking the same thing here? Most lifter experiments have used the voltages generated in old CRT monitors. Cool stuff, but dangerous.

    http://jnaudin.free.fr/html/zslift.htm
     
  7. eman12

    Thread Starter Active Member

    Oct 26, 2007
    41
    0
    yea, I am talikng about it.

    My lifter is ringing with the first vircuit(one transistor) and if I take one corner of it with an long string it trys to be at horizontal surface in the air(on 30V power supply). so I thought maybe the second push pull circuit would help me to give it more power, when I made the secend circuit I got smaller sparks in lower distances? so I was wondering why the second circuit which SEEMS to be a PUSH PULL circuit is not as powerfull as the first?!
    the secondary is a flyback transformer( and no, it doesnot have any built in rectifier)
     
  8. eman12

    Thread Starter Active Member

    Oct 26, 2007
    41
    0
    don't you think I will fade the half cycle with the first circuit?
     
  9. eman12

    Thread Starter Active Member

    Oct 26, 2007
    41
    0
    at least, can someone say me how the second circuit works as a push pull circuit?
     
  10. SgtWookie

    Expert

    Jul 17, 2007
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    1,728
    Sorry, I've been rather busy today.

    Actually, I did a bit of poking around on Bill Bowden's page:
    http://ourworld.compuserve.com/homepages/Bill_Bowden/

    and found this link:
    http://members.misty.com/don/igcoilhv.html

    To me, this is much more promising than the original circuit you were using, as the author of that circuit used a flyback transformer that would not typically be available; he just happened to "luck up" on finding a couple. The author of your circuit also admits that he frequently suffered from burned-out transistors, and has since moved on to a different device.

    I believe what's happening with your circuits is that the rectifier diode built into the HV tower is limiting your output.

    Don's circuit uses power MOSFETS which are able to handle significantly higher power levels than typically available (and affordable) transistors. It also is adjustable independent of the resonant frequency of the primary coils. Automotive ignition coils don't have a rectifier diode in the towers, and you can find them very cheaply at a junkyard. Just about any automotive coil will put out in excess of 30kv if you run the primaries hot enough (pass enough current through them).

    On the 2nd circuit - if you got the polarity of any of the windings backwards, you won't get a decent output. You'd also have to be very careful to have the exact same number of turns, turn spacing, and the same lengths of wire to make both sides resonate at about the same frequency. This can take some fiddling around. You would also want to match your transistors' gains. This won't make much of a difference when they are operating saturated, but it'll make a difference as to what the optimal number of turns is for the feedback winding.

    Try Don's circuit. It will be far easier to replicate his results than either of the other projects you're currently attempting.
     
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