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Temperature difference in a resistor

  1. May 29, 2013 #1
    I'm an absolute newbie and have just this one question:
    When I installed LED map lights, they would flicker unless the door was open. After someone advised me that I should solder resistors (which I did) the problem was fixed, BUT: I would like to know what is the difference in temp as I down want to start a fire in my car.

    Resistors are 2w 330ohm, I used T4W LEDs for which I guess are about 0.5w, and for voltage I think it's 12v.

    This is a guide from another forum:
    Here are a few photos of the light unit:
    Last edited: May 29, 2013
  2. jcsd
  3. May 29, 2013 #2


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    Difference in temperature between what and what, and in which conditions?

    Connected to 12V, the 330Ohm-resistor (resistorS?) draws something like .4W.

    12V is not the operating voltage of typical LEDs, however.
  4. May 29, 2013 #3


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    However, these LED's (T4W ) are designed for 12V car systems as a direct replacement for the
    "dome" lights etc in a car cabin
    They have their own built in current limiting resistor and heatsink

    The external resistor mod to stop flickering is an ineresting one :)

  5. May 30, 2013 #4
    I'd like to know how hot can resistors get, as I don't want them to melt any plastic and cause a fire.
  6. May 30, 2013 #5


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    That depends on the power they get and the temperature and heat conductivity of the environment.
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