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Power supply rating

Discussion in 'Electronic Design' started by Tom Sanders, Feb 23, 2004.

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  1. Tom Sanders

    Tom Sanders Guest


    I have a power supply rated at 500V dc and 0.5A. I am using this with
    two 10 Megaohm 0.25W in series to charge a capacitor of 10pF. Because
    of the two resistors in series, the current in the circuit would be
    0.25 uA. What does the current rating on the power supply mean? Is
    that given for safety reasons?

    Please help.


  2. Tim Wescott

    Tim Wescott Guest

    Go above the current rating and either the power supply will destroy itself
    or (hopefully) blow a fuse or go nicely into current limit, depending on its

    You have a whopping big monster of a power supply to do a job that could be
    done with a dry cell and a vibrator!
  3. It means you should get someone else to do whatever it is you are
    fooling with.

    Best regards,
    Spehro Pefhany
  4. Where would he put the dry cell?

    Best regards,
    Spehro Pefhany
  5. Tim Wescott

    Tim Wescott Guest

    Must. Resist. Potty. Joke...

    Sorry -- Dry cell, vibrator and _diode_, to make a simple flyback circuit.
    Point being he's using a 250W power supply to deliver an instantanious power
    of 25mW. Unless there's high winds and he's worried about the capacitor
    blowing away he's using way more power supply than he needs.
  6. I think its an 'embedded systems' joke.
    This might be something he's rigging up in the lab. Maybe that's the
    smallest 500V supply he has handy.

    But if he has to ask this simple a question, I'd suggest he not mess
    around with 500 volts.
    Or at least do so with someone with experience looking over the wiring
    before he throws the switch.
  7. God.... you're so smunggely. Next thing you'll be telling us how to program
    a 350milliongigaburp processor to do the job in 'real time'.

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