Current draw

Discussion in 'The Projects Forum' started by zander, Feb 28, 2009.

  1. zander

    Thread Starter New Member

    Jul 26, 2008
    6
    0
    I'm making a 12 volt appliance that uses a thermostat to switch on and off a halogen light bulb and pc fan at the same time.

    I've worked out the total amperage draw of all components should be about 950 ma when used togother.

    However I'm regularly breaking the 12v mains 1 amp power adapters.

    So my question is do you think I could be peaking over 1 amp when the thermostat switches on both the fan and bulb at the same time??

    Would it help if I just let the fan run all the time so its not starting an stopping, then just the bulb has to start from cold?

    Thanks
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    When a lamp is cold the resistance is lower, so it will draw more current at startup.

    Greetings,
    Bertus
     
  3. zander

    Thread Starter New Member

    Jul 26, 2008
    6
    0
    Hi
    So, do you know if the fan will draw more amps at start up compared to when its running.
    Also do you know if the lamp can draw more than its 10 watt rating?
    Thanks
     
  4. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    The fan startup will also draw a little more then running.
    The lamp will draw much more at startup.


    This quote comes from this wiki page:
    http://en.wikipedia.org/wiki/Incandescent_lamp

    Greetings,
    Bertus
     
    Last edited: Feb 28, 2009
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