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Loads on a Power Source

Discussion in 'Electronic Basics' started by [email protected], Jul 16, 2007.

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  1. Guest

    Can anyone explain why turning on another load in an electrical system
    causes the others to diminish in intensity? I notice in my car when
    it's running that the transmission indicator display dims and
    brightens with the on/off pattern of the turn signals. Is this
    because the extra amps result in an inability of the system to
    maintain voltage? How could this be if the car has so many other
    loads to carry on the system and the alternator compensating? I also
    have seen the same thing at home. My microwave light and timer
    display dim and brighten with the on/off of the microwave power during
    reduced power cooking. This too seems odd even though its so many
    watts because I am not using the maximum amps for the breaker.
    Additionally, the whole house could surely be demanding more amps on
    the utilty company's power supply, as could the community. Is this
    for some reason a strain on 120V?
  2. ehsjr

    ehsjr Guest

    Using the car as an example:

    +12 ---[R]---+---> to turn signal
    +---> to transmission indicator

    [R] in the above diagram will lower the voltage at the
    point labeled A by an amount equal to the current drawn
    by the turn signal times the value of R. R is the
    resistance in the wiring, fuse block and connectors between
    point A and the battery. When the turn signal is off it draws
    no current and the voltage at point A is higher because no
    voltage is dropped in the resistance. When the signal turns
    on, it draws current through the resistance and the voltage
    at point A lowers.

  3. neon


    Oct 21, 2006
    Th battery is the source of the power actualy the generator if running Those two items have very low inpedance and generaly don't move voltage wise with light load like a couple of amps If you see dimming is because the wireing of the car IXR drop makes it so. car manufacture is at fault by not providing proper wireing and that is the fact. same thing in your house if the heavy use appliances comes on and the wireing is in series wih another load it will dimm because of IXR drop. To mae things worst some apliances have a heavy inrush current.
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