Dual Ganged Pot

Discussion in 'Electronics Resources' started by awwende, Mar 19, 2010.

  1. awwende

    Thread Starter Active Member

    Feb 17, 2009
    39
    0
    I'm having problems finding pots that i need. What I'm working on is a power supply with variable voltage from 0-20V at 3A max. I'm using a lm317 with a bypass transistor to allow for more current.

    The LM317 uses a 5k trim pot to control Vout. I was going to use two 2.5k or a 5k and 1k in series to give me coarse and fine adjustment of my voltage. but I've seen a fair amount of power supplies that two knobs on top of each other, but i can't seem to find them anywhere.

    does anyone know where i get get a couple?
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    For the odd values, you may need to get a custom made pot. Concentric shafts will give the fine/coarse controls (although the trimmer will always be superior for absolute adjustment). Here is a link you can explore - http://www.potentiometers.com/
     
  3. rjenkins

    AAC Fanatic!

    Nov 6, 2005
    1,015
    69
    Another alternative is to use a 10 turn pot with a turns counting dial. That will give you very fine control and a scale for quick setting.
     
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