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AC Power Adapter Use

Discussion in 'General Electronics Discussion' started by jayfin, Mar 14, 2012.

  1. jayfin

    jayfin

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    Mar 14, 2012
    Can I use a 1 Amp AC power adapter on a device that calls for .5 amps without doing damage to the circuitry? This adapter is for use with an LED sign.
     
  2. duke37

    duke37

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    Jan 9, 2011
    Tip - put a zero in front of the decimal point, then it will not be lost.

    The adapter must have the right voltage and if DC, the right polarity.
    Get these things right and it should be OK.
     
  3. KMoffett

    KMoffett

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    Jan 21, 2009
    If the voltage of the adapter matches the voltage of the device, the device will draw only as much current as it needs. The 1 Amp on the adapter is the maximum current that it can safely provide. However...if the adapter is not the "regulated" type, the voltage will be about 1.4 times higher than the specified output voltage with a light load or no load. With those types you want the current rating of the adapter to be close to the current requirement of the device.

    Ken
     
  4. jayfin

    jayfin

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    Mar 14, 2012
    Thanks for the info

    I have very little knowledge about electrical or electronic stuff. Didn't even think about using a zero before the decimal point. I will give more info that is available
    LED Sign Information = 100-240VAC 50-60Hz 0.5A Class 2 ITE - 18VDC
    Radio Shack AC Adapter = input 120V AC 60Hz Output 12 VDC 1000mA Class 2
    With this added information, what are your thoughts about using this adapter?
     
  5. BobK

    BobK

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    Jan 5, 2010
    No good. You need an adapator that puts out 18V and at least 0.5A.

    Bob
     
  6. duke37

    duke37

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    Jan 9, 2011
    But, does the LED sign have its own mains to 18V supply?
     
  7. jayfin

    jayfin

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    Mar 14, 2012
    I guess I will have to locate and adapter that meets specs

    I do not know what you mean about mains. The only opening is a male fitting and the adapter has a female fitting. I don't know the size of the fitting. Might be either 2.1mm or 2.5mm. I do know that the Radio Shack adapter will turn on the sign but that doesn't mean that it won't cause harm to the system.
     
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    The lower input voltage may mean the sign is not as bright as it normally is, or that it is more prone to other issues (e.g. brownouts).

    As long as it seems to work OK, there is a very high probability (say 95%) that it's not going to harm either the device or the power supply.
     
  9. jayfin

    jayfin

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    Mar 14, 2012
    Another question about AC Adapter

    I have located online an AC power adapter that meets all of the requirements and I will most likely purchase it since it is very inexpensive and shipping and handling cost are minimal. What I would like to do unless it is not advisable is to cut the wire and splice in the wire with a different end fitting. Almost all of the fittings are straight but the one that I have on my old Radio Shack adapter is a right angle fitting which will work much better when mounting the sign on the wall. Do you see any problems in doing this?
     
  10. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Just make sure that you get the polarity right and that you insulate everything so that you don't short anything out.
     
  11. KMoffett

    KMoffett

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    Jan 21, 2009
    I think we would need a lot more information to help you.

    Input AC voltage?
    Input connection type?
    Output voltage: voltage?...AC or DC?...regulated or unregulated?
    Output current?...or current needed by the load device
    Output connector?

    Ken
     
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