Variable power supply using 9V batteries

Discussion in 'The Projects Forum' started by uceeam3, Mar 4, 2013.

  1. uceeam3

    Thread Starter New Member

    Mar 4, 2013
    2
    0
    Hi

    I am trying to build a variable power supply between 0-35v using 9V batteries. I tried to make this using a potential divider but i need to keep the current as low as possible. So am not sure about it. please help, thanks.
     
  2. ScottWang

    Moderator

    Aug 23, 2012
    4,853
    767
    You may try this way:
    9V batteries → MC34063 StepUp(Raising Voltage) → potentiometer → MOSFET → Vout

    Google MC34063.
     
    Last edited: Mar 4, 2013
  3. uceeam3

    Thread Starter New Member

    Mar 4, 2013
    2
    0
    All I need is a simple power supply preferably using just resistors to apply a bias to a piece of equipment that i am using for a short period of time
     
  4. blah2222

    Well-Known Member

    May 3, 2010
    554
    33
    In order to keep the voltage constant with different loads, you are going to need some sort of active device.

    Have a look at this IC and the circuits in the datasheet.
     
  5. ifixit

    Distinguished Member

    Nov 20, 2008
    638
    108
    This should work as long as the load current is much less than 3.5 mA.
     
  6. ScottWang

    Moderator

    Aug 23, 2012
    4,853
    767
    I'm not sure how much current you need, the basic circuit already done, you can adjust the values of resistors to suit your need.

    The Sw1 is designed for when the batteries is decreasing, then you can switch Sw1 on to increse the voltage.

    R4 is the false Load.

    [​IMG]
     
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