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Electric Adaptor choice

  1. May 14, 2015 #1
    At the back of my music keyboard's electric adaptor it says
    "INPUT: 230V, 50Hz 0.2A
    OUTPUT: 12V, 1.5A

    Suppose my adaptor busted and couldn't find the original replacement.
    Can I use a 9V instead? Will it work? Will it has to be 1.5A then?
    Power is=I^2 x R as well as I x V, does that mean as long as A value is 1.5A it justifies the formula and voltage is not important??
    Will my device burn if I used -say- 24V ?
    How flexible I can be?
     
  2. jcsd
  3. May 14, 2015 #2

    Drakkith

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    Your keyboard requires a 12 volt electrical power source, and nothing else will do. The adapter is there to turn mains electricity, 230 volts it seems, into 12 volt power. Using too little voltage will result in a failure of the keyboards electrical components, but probably won't burn your keyboard up (don't quote me on that). Too high of a voltage is likely to damage it. The amperage output is the rated max that can be safely drawn from the adapter. The keyboard doesn't always draw 1.5 amps, but it can draw up to 1.5 amps, so any adapter needs to be able to safely supply up to 1.5 amps of current at 12 volts. Also, if you do change adapters, keep in mind that the plug that connects the adapter to your device usually has a specific polarity configuration. If you don't use the right plug, then your keyboard can be damaged.
     
  4. May 14, 2015 #3

    CWatters

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    +1 to that.

    New adaptor has to be 12V but can be greater than 1.5A.

    In addition...Check the symbols on the adaptor to make sure its' 12V DC you need not 12V AC.
     
  5. May 14, 2015 #4
    In my experience a bit lower voltage almost always worked fine in many appliances wo/ motors (it shouldn't damage anything, at worst it won't work or malfunction, like any appliance whose battery is depleting), because usually they have a working range (ever the PSU rarely gives off the exact stated voltage, sometimes ever more) Higher voltage can damage or overheat components or short their lifespan, and reversing polarity almost always ends up in pop and smoke
     
  6. May 14, 2015 #5

    russ_watters

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    Just to expand, this also means any adapter rated for above 1.5 A should work too.
     
  7. May 14, 2015 #6

    russ_watters

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    While this is true, unfortunately it is impossible to know without testing.

    This is most noticeable and easiest to test for disposable batteries, where different chemistries have different peak voltages and the voltage of battery packs isn't a multiple of the rated voltages of the batteries in the pack. If you have a piece of electronics that fails on low bat and you test the voltage of the battery immediately after the failure, that should tell you the min required.
     
  8. May 14, 2015 #7
    Thank you.
     
  9. May 18, 2015 #8
    I'm not quite clear on one thing though, Why should an adapter with higher A be ok? doesn't that mean more current drawn and more dangerous??
     
  10. May 18, 2015 #9

    russ_watters

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    The adapter provides the voltage, but the load demands the amperage. So if you use a 2A adapter on a device that needs 1A, the device will draw 1A from the adapter.
     
  11. May 18, 2015 #10
    Russ Watters explained perfectly.
    2A on a power supply, for example, means "Maximum current allowed is 2A", NOT "It always provides 2A". It's different to voltage which never varies.
     
  12. May 18, 2015 #11
    Ok got it, thanks.
     
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