+5V Supply using 12V Wall Wart

Discussion in 'General Electronics Chat' started by miniengine, Sep 16, 2009.

  1. miniengine

    Thread Starter New Member

    Sep 6, 2009
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    Would a 12V 800mA wall wart suffice as a proper input to make a 5V Power Supply for Breadboard circuits needing less than 1 Amp current? Recommend a schematic please. Thank you
     
  2. nanovate

    Distinguished Member

    May 7, 2007
    665
    1
    Yes.
    The datasheets for a LM317 or LM7805 could be a starting point for a schematic. These would work without a heatsink to about 250 mA.
     
  3. elementalrage

    Active Member

    Jul 30, 2009
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  4. rjenkins

    AAC Fanatic!

    Nov 6, 2005
    1,015
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    A 9V one would be fine to run a 7805, the regulator would stay rather cooler.
     
  5. SgtWookie

    Expert

    Jul 17, 2007
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    You didn't say whether the output from the wall wart was AC or DC. That makes a difference in the design.
     
  6. elementalrage

    Active Member

    Jul 30, 2009
    59
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    Slightly off topic:

    Why is it that when I run a 78M05, for a PIC and 7 segment LED, there is no heat when reducing to 5v from 12v? Is the small amount of amperage I'm drawing the reason?
     
  7. miniengine

    Thread Starter New Member

    Sep 6, 2009
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    Output is DC.
     
  8. SgtWookie

    Expert

    Jul 17, 2007
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    Yes. It's best to start your own topic though; otherwise the thread can get confused very quickly.
     
  9. russ_hensel

    Well-Known Member

    Jan 11, 2009
    818
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    Yes. P = VI for DC
     
  10. SgtWookie

    Expert

    Jul 17, 2007
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    See the attached for how to connect a couple of regulators.
     
  11. miniengine

    Thread Starter New Member

    Sep 6, 2009
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    Thank you for your help. Ray
     
  12. SgtWookie

    Expert

    Jul 17, 2007
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    You're welcome, Ray.

    A note on the LM317 schematic - the terminal labeled as "COM" is actually the "ADJ" terminal.

    For more information on the LM317 regulator, go to National Semiconductor's site:
    http://www.national.com
    and download the datasheet for the LM117/LM317.
     
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