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-1kV pulse generator

Discussion in 'General Electronics Discussion' started by Oseania, Sep 18, 2014.

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  1. Oseania

    Oseania

    3
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    Sep 18, 2014
    Hi,

    I'm interested in building a -1kV pulse generator for my electrostatic experiments. The repetition rate of the pulses should be around 25Hz and the pulse width around 10 microseconds. As I am using this to build corona, the current output is minimal.

    I looked at the ignition coil driver circuits but I'm not sure if they can provide such a small pulse widths. I'm looking for a simple and cheap design. Does anyone have suggestions for suitable simple design.
     
  2. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
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    Nov 28, 2011
    Hi there and welcome to Electronics Point :)

    I think a ferrite cored transformer would be a good starting point, driven by a transistor or MOSFET that conducts for a short time before the pulse, to build up energy in the core, then turns OFF to produce a large flyback pulse.

    You can connect a high-voltage capacitor across the transformer to shape the pulse and provide crude voltage regulation. What shape do you want?

    What's your location? (There's a place for that in your profile.) What component suppliers do you use?
     
  3. Fish4Fun

    Fish4Fun So long, and Thanks for all the Fish!

    464
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    Aug 27, 2013
    Hi Oseania,

    Welcome to EP! 1kV is not going to get a lot of corona discharge unless the gap is really short.....ignition coils are fairly robust/cheap/easy....if you assume a V8 has 4 ignition cycles per revolution and that most V8's are capable of at least 6,000RPM, this would suggest that they are capable of at least 400hz, well beyond your 25hz target and are typically capable of well beyond 10kV....so I wouldn't rule them out casually.....The "Tesla Folks" wind large air-core transformers around cardboard cores...this is certainly an option.....Frequently to get really high voltages the use of a "condenser" (read: "capacitor") is employed to "ratchet" the voltage upward until the voltage "breaks over the gap"....but you likely know all this.....

    anyway....Are you attempting to build an Ozone generator or are you just "playing" with corona discharge?

    Fish
     
  4. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,270
    Nov 28, 2011
    Fish, I think the reason Oseania doesn't want to use the ignition coil idea is that the pulse would be too long. The pulse rate would be no problem. The inductance of an ignition coil is probably too high, although using a smalller "condenser" value would help to get a shorter pulse with the desired shape. Also, ignition coils are pretty big.

    I assumed Oseania knows why he wants a -1 kV, 10 µs pulse, but that's a fair question.
     
  5. Oseania

    Oseania

    3
    0
    Sep 18, 2014
    Hi folks,

    I understand that -1kV is a bit low and I can use higher voltages if required. So for example .10kV would be fine, I just have to make the setup larger. Regarding the ferrite coil idea, this sounds really interesting. I have not previously done anything similar so can you guys help me with suitable components? I'm currently at USA and do most of my shopping from Digikey and Farnell.
     
  6. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,270
    Nov 28, 2011
    Um... I can't give you any specifics, I'm afraid. If I was going to do this, I would get a range of cores, a few reels of wire, and some high-voltage pulse-withstanding capacitors around the 1~47 nF range, and do some experimentation.
     
  7. Fish4Fun

    Fish4Fun So long, and Thanks for all the Fish!

    464
    105
    Aug 27, 2013
    Oseania,

    Perhaps if you gave a few more details about what you are attempting to achieve we might be able to make better suggestions about how to approach the problem....for instance the first things that come to my mind when I think of HV pulses designed for corona discharge are 1) "Ignition Systems" (internal combustion engines//gas ignitors etc)... 2) "Tesla Toys" 3) Ozone Generators 4) Welding/Plasma Arc Starters(not fundamentally different than #1) ... and the list ends there, and is ordered by the frequency in which I see HV pulses mentioned/discussed....I am not saying there aren't other possible purposes....just saying I can't think of any right off the top of my head....and it might help us help you if we had some idea of the intended purpose....

    Fish
     
    KrisBlueNZ likes this.
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