Trouble identifying whether pots are linear/audio based on markings

Discussion in 'The Projects Forum' started by Videodrome, Apr 1, 2011.

  1. Videodrome

    Thread Starter Member

    Nov 12, 2009
    Hello folks,

    I need to replace a couple bent shafted pots and i'm having trouble telling whether they are audio or linear based off their package markings. The first pot is a surface mount pot with the printing 'M20KD' with '37..B' right below that. The next pot im having trouble with is a standard alpha style single gang 3 terminal with the printing 'M10KΩA'. both of these printings are confusing to me as i usually just deal with printings like 'B50Ω' or 'A2M', but am i correct in my assumption that the first one is B20K(linear) and the second one is A10K(audio)?
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    Got a meter? You can see the difference in the rate of resistance change using an ohmmeter.
  3. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    The second is most likely audio.

    Linear will have equal resistances in the top and bottom half. Audio will have unequal resistances in the top and bottom half.

    To test: Set the pot to it's mid way setting. Then read resistance from the wiper leg to each end.
  4. castley


    Jul 17, 2011
    If the pot reads half total value at the center position it is probably linear.If it is audio it will have a logarithmic taper. The value will change rapidly at one end and much more slowly at the other end.
  5. shortbus

    AAC Fanatic!

    Sep 30, 2009