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Will I fry my device?

Discussion in 'General Electronics Discussion' started by dutsnekcirf, Mar 21, 2011.

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  1. dutsnekcirf

    dutsnekcirf

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    Mar 21, 2011
    I have a device that I'd like to integrate into my car's electrical system. The device takes 12 vdc and 2 amps. Before really thinking this through I went to radioshak and picked up a generic cigarette lighter power adapter that outputs 12 vdc and 10 amps. I was planning to simply splice in the power connecter from my device into the cigarette lighter adapter and plug it in. Now I'm wondering if 10 amps is going to be too much for my device and fry it. What do you guys think?
     
  2. shrtrnd

    shrtrnd

    3,826
    527
    Jan 15, 2010
    Your device will draw only the amperage that it needs. The Radio Shack 10 amp reference, is to tell you that is the MAXIMUM current the CORD is designed to handle, NOT
    that you WILL draw 10 amps because you're using it.
    You'll be fine using the Radio Shack cord, just make SURE you've got the polarity right (positive and negative).
     
  3. dutsnekcirf

    dutsnekcirf

    2
    0
    Mar 21, 2011
    lol, that was the next question i was going to ask. Which one's usually positive? The cord has one that's all black and the other is black with a white stripe. I've searched for the answer online and I'm seeing conflicting oppinions. Thanks for your response Shrtrnd.
     
  4. shrtrnd

    shrtrnd

    3,826
    527
    Jan 15, 2010
    The outside shell of the cigarette lighter socket is the negative, it's grounded to the
    car chassis, which is electrical ground (negative) for the car.
    The metal button in the center of the end of the cigarette lighter socket, is the 12VDC (positive). On the cord you got from radio shack, the flat metal tabs on the side of the cigarette lighter plug, are the negative; they'll make contact with the outside shell of your cigarette lighter socket in the car. The metal button (usually spring-loaded), is the positive contact on your Radio Shack plug. It makes contact with the metal button
    in the bottom of the car's cigarette lighter socket.
    It's as easy as that.
     
  5. shrtrnd

    shrtrnd

    3,826
    527
    Jan 15, 2010
    Oh.
    You seem to be wondering which of the two wires on the Radio Shack cord, goes to which end of the cigarette lighter plug.
    I'm guessing you don't have an ohm-meter (multi-meter).
    If it's not designated on the plug or the cord (look at the assembly, and see if you can see
    a plus for positive marking on the plug where the wires come out, or actually stamped on the cord coming out of the plug:
    Then you need to think of a way to test the electrical continuity, (or you can call
    Radio Shack, and ask them which is which on the cord they sold you).
    Take any low voltage device, like a flashlight, or a battery operated transistor radio, or
    anything you won't get a shock from (high voltage). Take a length of any electrical wire,
    and touch one side of the battery contact, through each side of the Radio Shack cord (using the cord to make the completed electrical circuit, back to the battery operated device).
    All's you're trying to do, is identify which wire goes to which contact on the Radio Shack cord.
    The absolute easiest way, is to stop by Radio Shack with the cord. If the salesperson
    can't TELL you, he'll have a batterytester behind the counter, that he can use to make
    a complete circuit through the cord, to tell you which is positive and which is negative.
    It's a really simple test, you just need to run a very low voltage through the cord, to complete
    a circuit, so you know which wire is which.

    Good luck.
     
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