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Transformerless high voltage from 120VAC

Discussion in 'Electronic Basics' started by noname, May 29, 2007.

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  1. noname

    noname Guest

    I need to build a compact transformerless high voltage supply that
    will run off of 120VAC mains and produce at least 2000-4000 (AC or DC)
    volts with very low current. I figure what would be best is the
    "Walton-Cockroft voltage multiplier"

    How many capacitors (and what type, size, ect) would I have to use for
    this to work?

  2. John Larkin

    John Larkin Guest

    Roughly 60 capacitors, say 10 uF each, and 60 diodes... it sure won't
    be "compact."

  3. See

    Page 32 - Generates 7.5kV DC negative, 400uA.
  4. Ron M.

    Ron M. Guest

  5. default

    default Guest

    What size cap depends on how much power you want.

    Capacitor voltage is established by the input voltage to the chain.

    The URL you list, has the formula

    Eout = 2n*Epk - VDrop .... VDrop=0 under no load

    Voltage out, equals, 2 times the number of stages, and voltage peak of
    the input. (sine wave 120 VAC, times 1.4142 equals 170 Volts peak)

    You would need 12 stages to get 4 KV out and each stage consists of
    two diodes and two capacitors.

    The output of a Cockroft Walton is DC . . . always.

    There are variations in the design to give full wave output with twice
    the parts for twice the power.

    The bigger the size of the caps, the more output power and current.

    Ripple increases substantially when you try to pull off power, so CW
    multipliers are used for low current applications, like ionizers,
    loading the belts of Van De Graf machines with electrons, in TV sets
    to provide acceleration voltage, bug zappers, charging up caps to high
    voltages etc..

    The higher the frequency the more power you can get out of a given
    number of stages . . .

    Charge a cap with one and you could conceivably electrocute yourself
    with it. Connect the side shown grounded in the first schematic to
    the AC hot wire and you could electrocute yourself with 120 volts.

    An ionizing potential of ~10KV+ will charge objects near it with an
    electrostatic charge - causes static shocks if you are insulated from
    ground and near one spitting out ions, in a dry area.
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