Simple battery backup circuit

Discussion in 'The Projects Forum' started by Michel_e_r, May 30, 2008.

  1. Michel_e_r

    Thread Starter Member

    May 30, 2008
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    I'd like to design a simple circuit which is usually connected through an adapter and when it is not, it uses a common 12V battery or of the sort. How can I do this? I've thought of using relay and somehow make that work, but seems it will take more than that =P. Any ideas? Much thanks.
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    1,728
    Your request is really quite vague.

    What is your required voltage and current for sustaining the circuit?
    DC or AC? AC gets quite a bit more complicated.
     
  3. Michel_e_r

    Thread Starter Member

    May 30, 2008
    10
    0
    12 volts and AC circuit =/

    So, all I have is a power source adapter which is connected to the wall and when it is unplugged I need a battery to serve as backup to supply the voltage to the the rest of the circuit.
     
  4. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    So, 12VAC at what current? :confused:

    OK, so if it's a "wall wart" that's supplying the juice, it may not be AC, it could be DC.

    Still do not have much to go on here. :confused:
     
  5. Wendy

    Moderator

    Mar 24, 2008
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    If you are using DC (say a wall wart and a battery) then simple diodes will do the trick. Just make sure the wall wart has at least a couple of tenths more voltage than the battery, and the switching is automatic.
     
  6. Michel_e_r

    Thread Starter Member

    May 30, 2008
    10
    0
    Thank you SgtWookie and Bill_Marsden for putting up with my vagueness..English is not my strong language ;). I didn't know what a wall wart was but it sure is what I have. I read through other thread of using diodes and I'm sure that is what I need but I just started with electronic and not sure as to how to put it all. Is there a circuit available I can use as reference perhaps?


    Much thanks

    P.S This whole thing is to connect lights..so around 100mA-200mA. Very similar to this persons project..except he had schematic for which i do not have and is what I need.

    http://forum.allaboutcircuits.com/showthread.php?t=3106
     
    Last edited: May 30, 2008
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