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Heated Mirror

Discussion in 'General Electronics Discussion' started by Ricardo da Silva, Aug 2, 2014.

  1. Ricardo da Silva

    Ricardo da Silva

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    Aug 2, 2014
    Hi All

    I am trying to construct a heated mirror and need some expert help, because my basic knowledge is just not helping me get the job done.

    So I have taped 7170mm of nichrome wire 0.25 AI to the back of the mirror and applied up to 15V 4.0A DC to and it does not seem to be enough. Can anyone please recommend the correct power supply I need to warm the wire to a temperature that would be sufficient to warm the mirror.

    Many thanks in advance.
     
  2. Laplace

    Laplace

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    184
    Apr 4, 2010
    Have you insulated the back of the mirror to hold the heat in? If the tape should allow a loss of thermal contact between the wire and the mirror, hot spots will develop in the wire. How hot do those spots get? How hot when you increase the power?
     
  3. Ricardo da Silva

    Ricardo da Silva

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    Aug 2, 2014
    Thanks for the reply.

    The mirror will be hung against a tiles wall. i guess i could put an additional thin insulation layer to cover the whole back. what type of insulation would you recommend. having applied 15 volts at 4 amps did not heat the wire at all
     
  4. BobK

    BobK

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    Jan 5, 2010
    That is 60W, which should produce quite a bit of heat (ever touch a 60W light bulb that is on?)

    When you say "applying 15 Volts at 4 Amps" do you mean connecting the output of a power supply rated at 15V 4A, or do you mean you have actually measured the voltage and current at 15V and 4 Amps?

    Bob
     
  5. Ricardo da Silva

    Ricardo da Silva

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    Aug 2, 2014
    Yes I have connected a power supply rated at DC 15V 4A
     
  6. BobK

    BobK

    7,385
    1,562
    Jan 5, 2010
    Okay. That does not mean that your heater is pulling 4A. You need to put an ammeter in series with the power supply to determine how much current is actually being used. For all we know, there is an open circuit somewhere and there is no current being drawn, or there is a short and the power supply's protection is cutting it off.

    Bob
     
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