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How do i do high voltage frequency?

  1. Dec 28, 2007 #1
    how do i do high voltage frequency???

    i have been working with a 555 timer but i want to do a square wave 100 to 300 khz at up to 100 volts and 3-6 amps so i need something much larger any recomendations? thanks
     
  2. jcsd
  3. Dec 28, 2007 #2
    That is a lot of power. I think you can use the 555 timer as your small signal generator. You need to amplify this signal. Just putting it through a transformer will not be enough because the energy has to come from somewhere. You will need some power MOSFETs probably to amplify the signal to a high voltage, and these MOSFETS need to be rated for the amount of power you're trying to transfer (600 Watts). From this stage, depending on what voltage you amplified the original signal to, you can then pass the signal through a transformer to step up the voltage to what you need. The key is you need to amplify the original signal with an amplifier that can drive the power you need. Also you need to make sure there is minimal attenuation on your amplifier stages at the frequencies youre generating. I hope this sets you in the right direction, but there are some more experienced people here who can help you better.
     
  4. Dec 28, 2007 #3
    thanks TheAnalogKid83 now i have something to work with
     
  5. Dec 28, 2007 #4
    does anyone know if 600 watt mosfet's from an audio amplifier will work???
     
  6. Dec 28, 2007 #5
    possibly, although those are in a design where the signals amplified are much lower frequencies than the frequencies youre talking about. Check the datasheet for their part number and see what frequencies they operate at.
     
  7. Dec 28, 2007 #6
    also, i'm not the best at electronics, but if youre doing a square wave, a switching mosfet might be what youre looking for (i am assuming switching mosfets are on/off for square wave type waveforms instead of operating in the linear region of a transistor). A switching transistor is a lot easier to design than an amplifying transistor in my opinion, and this may be all that you need.
     
  8. Dec 28, 2007 #7

    berkeman

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    Why do you want to go to that high of a voltage? It's quite dangerous to be working with voltages over about 42V (Underwriter's Labs limit for low voltages), especially if you are just now learning about electronics. I'd strongly suggest that you stick with voltages more in the 30-40V range for now.
     
  9. Dec 28, 2007 #8

    dlgoff

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    Yes. And these high frequencies can easily couple into objects; like your ring (glowing red hot almost instantaneously) and could boil you bodily fluids.

    Berkeman, correct me if I'm wrong.
     
  10. Dec 28, 2007 #9

    berkeman

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    Not really at 300kHz. That would be more like microwave oven frequencies in the ISM band around 2.4GHz. The main risk of <1MHz high voltage AC waveforms (and the HV DC power supplies for powering the amplifier circuits) is from electric shock. Once you get into the MHz region, you add the issue that you are violating FCC rules about putting out harmful interfence with broadcast radio and other bands. You will get a very serious knock on your door if you do that.
     
  11. Dec 30, 2007 #10

    dlgoff

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    My bad. I saw MHz when the OP said kHz.

    The ring thing came from a story a old ham told me when I was a kid. He was matching his transmitter to an antenna by taping a tuning coil. He said that he accidentally aligned his finger with the coil and the ring almost burned his finger off.
     
  12. Dec 31, 2007 #11

    berkeman

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    Oh, baby! Yeah, when you're talking kW of transmit power, you've got to be pretty careful. Yeowtch!
     
  13. Jan 1, 2008 #12
    thanks for the concern and the good information, and i think i will leave the high power stuff for the experts, i found what i was looking for on ebay. this is a great forum though and i will be back
     
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