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Novice Help AC DC Loadlines 6J5

Discussion in 'Electronic Basics' started by GP53, Dec 1, 2004.

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  1. GP53

    GP53 Guest


    6J5 Triode Circuit

    I'm looking for some help. Why when I use an AC plate
    supply(250VAC/RMS), are the voltage values in the circuit different than
    when I use a DC plate supply(250VDC) in the same circuit. The grid
    supply is -4VDC and I've got a 25K sense resistor in series to the
    plate(10ma of current). All the numbers using DC calculate out just
    fine. When I use an AC supply, voltages are different. TIA.

  2. John Fields

    John Fields Guest

  3. Tim Williams

    Tim Williams Guest

    I'm with John, what's the AC about eh?
    It'll be at least half due to the plate half-wave rectifying the input.
    Depending on the circuit (and how you measure it) it may be anywhere from
    peak value, to a nonlinear middle point, or negative. (The nonlinearity
    being how the tube responds according to a 3/2 power law, as opposed to
    assuming the tube is a constant resistance = Rp while forward biased.)

  4. GP53

    GP53 Guest


    In order to curve trace this circuit on a scope, an AC supply is used as
    a sweeping voltage. One leg of 250VAC secondary to anode, and the other
    though the sense resistor, then to the cathode.

  5. John Fields

    John Fields Guest

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