Heating Element Experiment

Discussion in 'The Projects Forum' started by pradsy90, Nov 10, 2013.

  1. pradsy90

    Thread Starter New Member

    Nov 4, 2013
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    I took a 120v TO 12v dc adaptor which gives 500 mA.

    I cut the plug, split the wires (exposed copper) and connected them to two nails which have a heating element wire between them. The nails are 7 inches apart. The heating element wire was from a salvaged toaster. The wire won't heat up.

    Any idea why? Is the current not enough?

    Regards,
    Pradhip. S
     
  2. Metalmann

    Active Member

    Dec 8, 2012
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    Yeah, I would say not enough voltage or current. Or, both.

    Haven't tried that experiment yet.;)
     
  3. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Whats the resistance of the "heating element" you are using?
     
  4. killivolt

    Active Member

    Jan 10, 2010
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    It may seem like a short and just pull the supply down at 500ma. Your connection could be poor. Connect directly to the copper wire and eliminate the nails. If you could measure the heat before and after you maybe heating but, there just isn't enough amperage.
     
  5. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    To avoid overloading your power supply, you should limit the current to approximately one-half of its rated output. Thus, 500mA divided by 2 is 250mA. To allow 250mA to flow, given a 12V supply, your resistance element should be 48 ohms, which would yield 3 watts of heat. Granted, three watts is not a lot of heat, but if it's concentrated in a small piece of heating element, it could get hot enough to burn skin or to start a fire.

    Be careful!
     
  6. #12

    Expert

    Nov 30, 2010
    16,343
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    This is why $4 multimeters were invented. With no measurements about the actual resistance, temperature, current, voltage, or power, we have pretty much nothing to work with. Even decades of experience and a barrel of human compassion will only go so far.
     
    Metalmann likes this.
  7. Dr.killjoy

    Well-Known Member

    Apr 28, 2013
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    I would guess not enough current ...
    Doesn't a toaster run off AC voltage???
     
  8. #12

    Expert

    Nov 30, 2010
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    Yes, but irrelevant. It's just a resistor.
     
  9. killivolt

    Active Member

    Jan 10, 2010
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    The average toaster heating element is 70ohms. At 120vac and about 1.8amps once it reaches temp the resistance drops as the current follows approximately 1.5amps.
     
  10. GetDeviceInfo

    Senior Member

    Jun 7, 2009
    1,571
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    How Did you measure the temperature rise?
     
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