DC Polarity Question

Discussion in 'The Projects Forum' started by arfinator, Nov 22, 2010.

  1. arfinator

    Thread Starter New Member

    Nov 21, 2010
    1
    0
    Hey, guys!

    This is my first post here, thought I have looked around quite a bit. Everything on here has helped immensely!

    I have a AC/DC transformer that outputs both 12VDC and -12VDC relative to the ground. Can I use the -12VDC output without changing anything, or do I need to include something to change that to +12V?

    If so, how might I do that?

    Thank you so much, and I look forward to your response.

    Hess

    Please note that as of right now, this is an entirely theoretical project. I plan to have it looked over to ensure my safety and the safety of other users before it is put into practice. :)
     
  2. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    If it is a dual output power supply, you should have a black jack (-12V), green jack (ground), and Red jack (+12V), or colors similar to that. If you measure between the red and black jacks, a DMM will show 24V.

    Usually, -12V is only 1.5A, while +12V can be 1.5 to 40Amps (depending on if you are using an ATX computer supply or basic hobby type supply) The max current from -12V is the limitation on using the 24V supply.

    If not interested in "bridging" for 24V, then ensure both -12V and +12V are regulated, you can do this by measuring voltage without a load and writing it down, then hooking up a 12V light bulb, and the voltage should be within 0.1V of unloaded for a regulated supply.

    If this doesn't match what you are looking at, please post a photo.
     
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