How do I power a circut with battery and a DC adapter?

Discussion in 'General Electronics Chat' started by RemoWest, Feb 26, 2015.

  1. RemoWest

    Thread Starter Member

    Feb 9, 2015
    33
    0
    I have a project that I'd like to power with a 12 battery and a 12 Volt DC adapter. I would like the circuit to be powered by the "battery" when the DC adapter in not plugged into the "project. I'm using a DC Jack to connect the DC adapter to the project. The DC adapter is 12 Volts and 1 Amp, The battery is an a A23 also 12 Volts.

    I would need the circuit to primarily operate on the DC adapter. and switch to the battery when the DC power "jack" is removed. I don't want to use an external switch to cycle between power sources. I want that function to be automatic.

    Could one of you guys that know how to do this post up a schematic for me, I'd really appreciate that.:D

    I imagine this is Electronics engineering 101 to most of you guys, but I don't engineer electronics.:confused::(

    Thanks.
     
  2. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    get a jack with 3 connections, the third is a switched connection when the plug is inserted. like an earphone jack cuts off the speaker when the eearphone is plugged in.
     
  3. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    Or use a two diode or-gate to power the load. Chances are that the Wall-Wart DC power-supply has a higher voltage out than the battery, so while the Wall-Wart is plugged in, the load current comes only from it...

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    Last edited: Feb 26, 2015
  4. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,978
    744
    put a diode like 1N4001in series with the battery to the adapter supply, the battery will be disconnected when you connect the adapter.
     
  5. flat5

    Active Member

    Nov 13, 2008
    403
    17
    Dodgydave
    Perhaps MikeML's circuit is safer. If the adapter is just unplugged the battery will not feed into the adapter.
     
  6. RemoWest

    Thread Starter Member

    Feb 9, 2015
    33
    0
    Thanks for all the replies guys, awesome.:cool:

    As per alfacliff, wouldn't the 3 pin jack connector be the way to go, Since I'll be using it anyway? And since it allows the "switching" function basically... so the 12 V battery and 12 V Adapter can operate independently of each other, as I wanted. Also preventing any voltage back feeding in the circuit, and no diodes needed... Correct? :)
     
    Last edited: Feb 26, 2015
  7. flat5

    Active Member

    Nov 13, 2008
    403
    17
    yep. That's how the world does it :)
     
  8. RemoWest

    Thread Starter Member

    Feb 9, 2015
    33
    0
    Thanks again to all you guys!


    I'm still working on this circut. Other projects and some health issues holding me up ...
     
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