rocker up and down pedal matching pot values

Discussion in 'General Electronics Chat' started by relicmarks, Oct 23, 2009.

  1. relicmarks

    Thread Starter Active Member

    Oct 13, 2006
    355
    0
    The LFO speed/rate pot value is 100K

    The rocker pedal that goes up and down using your foot only rocks the 100k pot from 20K to 80K , its chopping off the lower part and upper part of the SWING/range

    How can i get the full swing/range of zero ohms to 100K?

    The rocker pedal is fixed to only swing at 270 degree's so its limiting the 100K pot inside the rocker pedal so i can't get really slow LFO speed/rate or really fast speed/rates, only inbetween in the middle of the 100K pot its varying.

    The rocker pedal doesn't start off at Zero ohms , it starts the 100k pot at about 10 degree's so the starting point is like 10K or 20K

    The rocker pedal is like someone's hands only swinging the volume knob from 3 to 7 not 0 to 10 , so you don't get the full range of the 100K linear pot

    I'm having the same problem with a LFO circuit speed/rate pot is 1 meg ohm linear , the rocker pedal is only swinging the knob from 3 to 7 not from 0 to 10 so its not letting me get my LFO's slow speed or rate speeds at all only in the middle

    i have one rocker pedal with a 100K linear pot for LFO circuit#1
    i have one rocker pedal with a 1 meg linear pot for LFO circuit#2

    What can i do to fix this problem please?
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Most pots swing about 270 degrees, unless they are multi-turn pots.
    If your pedal is only swinging it from 3 to 7 o'clock, that's only about 150 degrees of travel.

    There are some special-purpose pots (like for automotive throttle position sensors) that have a 90° swing from min to max.

    It might be possible to change the linkage from your pedal to the pot to allow further travel. However, without any photos of what it looks like, it's hard to say if that's even possible.
     
  3. relicmarks

    Thread Starter Active Member

    Oct 13, 2006
    355
    0
    http://www.m-audio.com/products/en_us/EXP.html

    you use your foot to push it up and down , which only moves it 150 degree rotation so its limiting the 100K or 1 meg pot value inside the pedal

    This is my problem is there is no way of changing the pedal to rock up and down more than 150 degree its very limited so its chopping off the lower and higher resistance track values

    I even tried putting in a 250K pot or 500K pot and trying to experiment with taper values resistors across the outside terminals to make it 100K in parallel total

    Taking a 250K pot and putting a resistor across the outside terminals to make it 100K in parallel , but the pot just was not varying much resistance

    I tried taking resistors and putting them from one outside terminal to the wiper to try to get it to swing to the lower speed and higher speed

    Taking a 100k pot and putting a resistor from one of the outside terminal to the wiper so the 100k pot was like at position zero or 1 , put the resistance value still stayed at the 150 degrees, it overides any parallel resistors or something

    If the 100K pot starting point is say at 10K and not a 1 ohms , how can i ever get is below 10K?
     
  4. relicmarks

    Thread Starter Active Member

    Oct 13, 2006
    355
    0
    How can i turn a 10K linear pot into a pseudo 100K pot?

    How can i turn a 10K linear pot into a pseudo 1 meg pot?

    Here is the schematic
    http://www.vguitarforums.com/smf/in...2f311ff0&action=dlattach;topic=33.0;attach=44

    Is this a passive adder circuit? its a 10K pot in series with a 50K rheostat to the shield

    The 50K rheostat does not add resistance , i don't know really what it does to the range/swing of the travel
     
  5. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Why don't you just get a Roland EV-5 pedal? You won't have these kinds of problems

    The circuit that you posted is simply a passive adder. I'm not sure if VR1 or VR2 is the one controlled by the pedal. I really don't want to take apart my EV-5 to find out.
     
  6. relicmarks

    Thread Starter Active Member

    Oct 13, 2006
    355
    0
    The roland EV-5 is the same thing as the M-audio expression pedal same schematic

    Because the EV-5 or M-audio doesn't work right with 100K or 1 meg ohm circuits

    THe EV-5 only works with 10K circuits

    THe 10k pot varys the rocker pedal , the 50K is the taper pot on the side of the pedal
     
  7. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    OK, so you replaced the original M-audio pedal pot with a different pot, correct?
     
  8. relicmarks

    Thread Starter Active Member

    Oct 13, 2006
    355
    0
    yes , the orginal pot was 10K

    I put in a 100K linear pot to "match" the LFO speed/rate pot which is 100K pot linear

    Because the 10K linear pot only changed the LFO speed not very much

    When i put in the 100K linear pot it only swings the range very narrow because of the pedals travel is only 150 degree

    270 degrees - 150 degrees = 120 degrees i'm loosing

    60 degrees/rotations of the 100K pot on the lower/bottom half and 60 degrees/rotations on the upper half

    I even tried using a 100K Audio taper , it made no difference because the Lower and upper half is still Chopped off by the pedals travel

    I even tried using the 10K linear pot and putting a 100K in series like the passive adder , the 10K linear pot still didn't work right

    I have the 100K pot which is MAtched to the LFO circuit for the speed pot
    but my problem is

    How can i get Zero to 100K in a 150 degree/rotation?

    What would the passive adder values be? and how should i hook it up?
     
  9. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You need to find a 100k pot that requires less than 150° travel over it's full range of resistance.

    Either that, or you will have to design and build a pedal that can swing a pot through 270° travel.
     
  10. relicmarks

    Thread Starter Active Member

    Oct 13, 2006
    355
    0
    So there is no way to do a passive adder circuit? or using taper resistors or something?

    i would need a passive adder on the upper half and a passive subtractor on the lower half to make it get the whole range it seems

    a 100k pot that requires less than 150° travel over it's full range of resistance.

    Is this custom? or you think i can find these?

    I seem different taper pots linear,audio,reversed, etc

    If i put in a 250K pot or a 500K pot to replace the 100K, then maybe i would just need a passive subtract circuit to trim down the 250K to a 100K value

    Or if i put in a 50K linear pot ( variable ) and another FIXED 50K pot in series that would a passive adder circuit = 100K , but its only varying the 50K linear pot of the rocker pedal
     
Loading...