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Dual polarity power supply for circuits

Discussion in 'Power Electronics' started by dayanj, Sep 29, 2010.

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  1. dayanj

    dayanj

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    0
    Sep 16, 2010
    I am looking for a dual polarity (+/-6V) power supply for use with simple circuits.

    I found these DC to DC converters which have +/- 12V outputs. Do you think I can use that +12 and -12V outputs connected to two potentiometers to regulate it to any voltage below 12?

    I have attached a sketch of what I plan to do? are there any potential barriers for using it like this?
    thanks

    DJ
     

    Attached Files:

  2. davenn

    davenn Moderator

    13,837
    1,952
    Sep 5, 2009
    hi there DJ

    a voltage divider like that would be ok for low currents any signif current and the resistors are gonna get real hot.
    you would be better off using +5V and a -5V voltage regulators off each of the + and -
    rails. (3 pin 7805 and 7905 Reg chips for example)
    You didnt state what your power supply's current capabilities need to be ? ie. what sort of current is the load going to draw from each supply rail ?

    Dave
     
  3. shrtrnd

    shrtrnd

    3,822
    519
    Jan 15, 2010
    Yeah, a little more info about what you're going to use it for, would help.
    If you need the 6VDC, you could bump up to the 7808/7908 (8Volt regulators), with a fixed resistor to drop the 8V to 6V. If you expect high currents, get the TO-3 power transistor package. And like davenn said, you gotta be aware of your current draw, for the right size dropping resistor.
    A high current dc/dc converter is going to run you some cash, and the voltage regulator idea from davenn would be a lot cheaper.
     
  4. dayanj

    dayanj

    15
    0
    Sep 16, 2010
    Thanks a lot for your replies!!
    My applications are phase locked loop with LM 565/ NE 565 in FM demodulation mode,
    and some simple op amp circuits like voltage multipliers etc.

    I found that voltage regulators, which seems a good option for me to use combining with +12 and -12 outputs of DC-DC converter. Thanks a lot again!!
     
    Last edited: Sep 29, 2010
  5. shrtrnd

    shrtrnd

    3,822
    519
    Jan 15, 2010
    Low current circuit, ....
    Your circuit should be pretty simple and inexpensive.
     
  6. dayanj

    dayanj

    15
    0
    Sep 16, 2010
    Thanks a lot

    DJ
     
    Last edited: Sep 29, 2010
  7. dayanj

    dayanj

    15
    0
    Sep 16, 2010
    btw, are there any dual polarity power supplies commercially available for this purpose?
    ideal one should have three outputs wit +,- and ground. and output can vary between +/- 5V to +/- 12V ?
     
  8. Militoy

    Militoy

    180
    0
    Aug 24, 2010
    If you don't need more than around 100mA on each output - you could use a dual adjustable LDO linear regulator like the LT3032. They're good for +/- 1.22V up to +/- 20V or so. They're not technically a "power supply" - as you'll have to feed in unregulated DC - like from a dual-complimentary rectifier.
     
  9. dayanj

    dayanj

    15
    0
    Sep 16, 2010
    Thank you! I think that is the best option for me for my range of applications!!
     
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