PWM power supplies

Discussion in 'General Electronics Chat' started by RodneyB, Mar 16, 2013.

  1. RodneyB

    Thread Starter Well-Known Member

    Apr 28, 2012
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    I have been looking at these power supplies and am begining to understand the theory behind PWM power supplies.

    I have then been searching the net to try and see how in small Cell phone chargers they dont use transformers.

    How do they get it from 220 Volt to the control voltage.
     
  2. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    Last edited: Mar 16, 2013
  3. crutschow

    Expert

    Mar 14, 2008
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    They use transformers but they can be much smaller since the switching frequency of their conversion process is much higher frequency than the line frequency, and the amount of transformer iron required is inversely proportional to frequency.
     
  4. RodneyB

    Thread Starter Well-Known Member

    Apr 28, 2012
    680
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    Thanks very much for the Help, I have cut open my cell phone charger and seen the E core type transformer.
     
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