What Can a 12v AC Power Supply Be Used For?

Discussion in 'Power Electronics' started by Zohar, Nov 16, 2016.

  1. Zohar

    Thread Starter Member

    Nov 19, 2015
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    1
    Hi

    I had a 2.0 set of Computer Speakers, that decided to die recently.
    The AC Adapter is still working perfect tho.
    It is a heavy (transformer based) Power Supply.

    Its sticker says 12v 3A, and for years I was sure it is DC output..
    But today when I measured it with with a Multimeter,
    when the multimeter was on DC mode, the display showed 0v..
    I thought it might be dead too, but then I decided to try to measure its output on AC mode,
    and surprise, it says 14.4v..

    So it is AC output apparently.
    (the sticker on it does not mention AC or DC)

    What can I do with it?

    (and why did the speakers come with a 12v AC and not 12v DC Power Supply?)


    Thank you
     
    Last edited: Nov 16, 2016
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    The Speaker has the rectifier in it.
    Basically the speaker needs 12VAC at around 3Amps to function.
     
  3. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    You can use the 12VAC adapter to produce around 16V DC at 1.8A DC.
     
  4. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    ...with proper supporting circuitry.

    Or you can use it to power a load that requires <3A at 12
    VAC :rolleyes:
     
  5. Zohar

    Thread Starter Member

    Nov 19, 2015
    67
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    Do the 12v amplifier modules that are sold on eBay, expect 12v DC or 12v AC?
     
  6. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    If the spec say so.
     
  7. crutschow

    Expert

    Mar 14, 2008
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    Unless it says otherwise, it's likely DC.
     
  8. Zohar

    Thread Starter Member

    Nov 19, 2015
    67
    1
    Thank you.

    OK, seems that there will not be any use soon for this AC Output power supply..
    (yet I might still keep it.. who knows If one day it might be needed)
     
  9. MaxHeadRoom

    Expert

    Jul 18, 2013
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    I picked one of the miniature stereo amps, IIRC it was around $5.00.
    They all tend to state the voltage range and current, all DC as far as I have seen.
    Max.
     
  10. Zohar

    Thread Starter Member

    Nov 19, 2015
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    Thank you Max

    If anyone can recall a situation in which he needed an AC output power supply, please write..
     
  11. crutschow

    Expert

    Mar 14, 2008
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    You can always convert it to DC by adding a bridge rectifier, a filter capacitor, and a voltage regulator such as an LM317 (adjustable) or an LM7812 (fixed 12V).
     
  12. Zohar

    Thread Starter Member

    Nov 19, 2015
    67
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    You have a point :)
    Thank you for that idea
     
  13. #12

    Expert

    Nov 30, 2010
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    I have at least 50 wall warts. They have many different voltages, AC and DC. Most of the time, I use them to hold down cardboard boxes and 2 pound coffee cans. When anybody needs one, I give it to them. This has saved speaker sets, telephone chargers, battery chargers, laptop computers, and several other things from going to the trash can.
     
  14. Zohar

    Thread Starter Member

    Nov 19, 2015
    67
    1
    Yeah I save Power Supplies too, but until ow they've all been DC Output..

    OK then I will save it, after all it's 3A, not some low ampere one..
     
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