Quick question

Discussion in 'General Electronics Chat' started by Redscarf, Sep 1, 2015.

  1. Redscarf

    Thread Starter New Member

    Jan 28, 2015
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    Hey guys, i was just wondering if I had a 8.45V power source that provides about 90mA what would you recommend as the best way to get the current up to at least 550mA? Thanks in advance!
     
  2. dl324

    Distinguished Member

    Mar 30, 2015
    3,242
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    Assuming you want 8.45V out, you need a different power source.
     
  3. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
    2,802
    832
    1) AC or DC? If the former, get a 6.1:1 transformer and you'll get about 1.4 V at approximately 550mA. If you need 8.45V, then you can't do it with just what you have,

    2) Get a more powerful power source.
     
  4. Redscarf

    Thread Starter New Member

    Jan 28, 2015
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    DC, but all right that's all I guess.
     
  5. Redscarf

    Thread Starter New Member

    Jan 28, 2015
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    Oh what if I use a transistor
     
  6. dl324

    Distinguished Member

    Mar 30, 2015
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    At 100% efficiency, power in = power out. Your power source, in round numbers, is 0.85W. At 500mA, you could get a volt or so...
     
  7. Redscarf

    Thread Starter New Member

    Jan 28, 2015
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    Oh I see
     
  8. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    You just need to know the math to understand what you can/can't get..

    Volts x Amps = Watts
    so
    8.5V x .09A = .765watts of power available


    Now Watts / Amps = Volts
    so
    .765w/.55a=1.4V

    So assuming 100% efficiency (and you won't get that in the real world) as stated above you could supply 550mA BUT that would only be at 1.4V

    This chart shows you all the ways to use volts/amps/resistance/wattage to figure out each other.
    http://www.ohmslawcalculator.com/ohms-law-wheel
     
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