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Simple 12v 3amp power supply

Discussion in 'Electronics Homework Help' started by Suny, Sep 20, 2016.

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  1. Suny

    Suny

    7
    1
    Sep 20, 2016
    I have a 12v 3 amp transformer.how can I supply 3 amp power?? Pls give a simplest circuit.
     
  2. duke37

    duke37

    5,364
    769
    Jan 9, 2011
    Just connect to the transformer output. You will get 12V AC at up to 3A, the maximum power will be 12*3 = 36W.
    What will be using the power?
     
  3. Suny

    Suny

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    Sep 20, 2016
    I need dc power for charge my 12v 9AH battery.
     
  4. duke37

    duke37

    5,364
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    Jan 9, 2011
    To change AC to DC you need a rectifier. The best solution is to use a bridge which can be made from four diodes or a bridge rectifier which is a square block with four connections, two for AC and positive a negative output. You may need a heat sink if running at the full 3A.

    To limit the current to a safe level, you could place a bulb in series. I have a tame mechanic friend who saves me headlight bulbs which have one broken filament. An ampere meter whould be advantageous as would a voltmeter. Car alternators are usually set to limit charge to 13.8 to 14V for lead/acid batteries.
     
  5. Suny

    Suny

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    Sep 20, 2016
    I also need a full charge mediam and low charge indicator. Would u help me?
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    You won't get 3A DC unless you use a switch mode regulator. With a linear regulator the max current without overloading the transformer is a little over 2A.
     
  7. davenn

    davenn Moderator

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    1,892
    Sep 5, 2009
    what sort of battery ? lead acid, sealed lead acid, something else ?

    different batteries require different charging methods
     
  8. Suny

    Suny

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    1
    Sep 20, 2016
    Lead acid battery
     
    davenn likes this.
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