PSU Circuit Help

Discussion in 'General Electronics Chat' started by oidium45, May 10, 2010.

  1. oidium45

    Thread Starter Active Member

    Apr 24, 2010
    130
    8
    Ok... After considering the good information that everyone was so kind to provide me, I have decided to try something else.

    How would I modify a circuit similar to the one below to produce 12-24v rather than 0-24v? It doesn't have to be exactly 12-24v. It is just a ball park figure.
    This is beyond my current knowledge of circuits.
     
  2. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    What kind of amperage are you looking for?
     
  3. oidium45

    Thread Starter Active Member

    Apr 24, 2010
    130
    8
    Whatever I can get out of the chip. It is rated for 1.5A so anywhere from 1A-1.5A is good.
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Set R2 to produce 12 volts. Measure its resistance and find a fixed resistor of that value. Place that resistor between R2 and ground. Now the regulator will vary between 12 volts and the maximum.
     
  5. tracecom

    AAC Fanatic!

    Apr 16, 2010
    3,871
    1,394
    R2 = R1 * ( (vout/1.25) -1 )
    R2 = 240 * ( (12/1.25) -1)
    R2 = 240 * 8.6
    R2 = 2064Ω
     
  6. oidium45

    Thread Starter Active Member

    Apr 24, 2010
    130
    8
    Thank you retched, beenthere, and tracecom! I appreciate the help. I think that I have asked a question in which I should have already known the answer.
     
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