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What is a safe way to charge myself to 300V?

  1. Apr 6, 2009 #1
    Hi,

    I am trying to charge my body to voltages around 300V. I have a high voltage DC power supply; I can set the current limit down to about 10uA. I was also thinking about using a series resistor between me and the output. Is this safe? How safe? Is there a safer way to charge myself !accurately!?

    Thanks
     
  2. jcsd
  3. Apr 6, 2009 #2

    mgb_phys

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  4. Apr 6, 2009 #3

    berkeman

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    You definitely need to tell us the context of this question.
     
  5. Apr 6, 2009 #4
    Hi,

    I am studying some items related to electrostatic discharge. In the past, I have just walked around on a carpet for a while, or used a Van de Graaff generator to electrify myself. I need to get a bit more quantitative though.

    I could just charge myself with the carpet, and use some nice way to measure my voltage, but I don't have the equipment to do this (an electrometer).

    Thanks for your help
     
  6. Apr 6, 2009 #5

    mgb_phys

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    Charging yourself to 300v isn't too much of a problem - assuming you take care to insulate yourself, make sure you are using DC (!!!!) and have a nice big current limiting resistor.

    Measuring the voltage is trickier.
    The capacitance of a person is typically 100pf. So at 300V you would only have 30nC of charge on you. If you used a high-end Digital meter or scope with 10M input impedance, the time constant would be tiny.
     
  7. Apr 7, 2009 #6
    What's a good way to insulate myself? I've got rubber soles, is that good enough?

    Thanks
     
  8. Apr 7, 2009 #7

    berkeman

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    Yeah, that's fine. It depends a bit on the humidity, right? Also, it sounds like an electrometer would be a good project for you to build for all of this, eh?
     
  9. Apr 8, 2009 #8
    Interesting suggestion; what kind of electrometer would be best to build?

    I've built some amateurish electrometers, kinda like the one shown here:

    http://amasci.com/electrom/e-field2.html

    but that really doesn't offer the precision I need. Where I work, we have also have a rotating electrode type electrometer, but that hasn't satisfied me either.
     
  10. Apr 8, 2009 #9

    vanesch

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    Be sure to calculate the resistor correctly. In no case you should be able to receive more than a few mA. Safest to stay below, say, 1 mA or so (even assuming you're a short to ground). For 300 V you'd need then at least 300 KOhm. Also be sure to have a resistor that can stand the voltage.

    From 15 mA onwards, it becomes dangerous.
     
  11. Apr 8, 2009 #10
    Thanks for your input. I am able to limit the current output of the supply, so I should be OK. I will take your suggestion on the resistor anyhow, thanks.
     
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