multiple power sources (DC circuits)

Discussion in 'General Electronics Chat' started by LukeDXB, May 26, 2008.

  1. LukeDXB

    LukeDXB Thread Starter New Member

    Joined:
    May 25, 2008
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    Hi Everyone,

    I have a general question.

    I can calculate series and parallel circuits ok, with one power source, such as a battery but how do I work out resistance values when there are two power sources (in a DC circuit)?

    For example, two 9v batterys wired in series, with 1 X 5 ohm and 1 X 10 ohm resistor and a 12v lamp - all in series.

    Regards,

    Luke
     
    #1
  2. nanovate

    nanovate Distinguished Member

    Joined:
    May 7, 2007
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    add them together
     
    #2
  3. John Luciani

    John Luciani Active Member

    Joined:
    Apr 3, 2007
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    The general method would be to use superposition. You determine the effect due to each
    power source individually, by disabling all but one source, and add the effects.

    To disable a voltage source replace it with a short circuit. To disable a current source
    replace it with an open circuit.

    For two equal voltage sources in series disabling one source gives you a current V/R.
    Disabling the second source also gives you a current V/R. Adding the two currents
    together gives you 2V/R.

    (* jcl *)
     
    #3
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