Pots with a shorter travel? *noob alert*

[scumbag]

OK, so I have been messing around with my wah, and am also interested in making expression pedals for some of my other effects. What I have learned from the wah, is that moving the pedal from toe to heel down doesn't sweep the pot along the full length of it's available travel. I'd really like to have the d.time on my delay pedal foot controllable, but I'm not prepared to sacrifice half of the available range. ie. i want the pedal to make the pot turn all the way from zero to full. I could do this with some little gears, but that seems like a bit of a pain.

Does anyone make pots with the same range, over a shorter travel?

I hope I explained that well enough...

[petemoore]

  You can probably mimic the value and taper of the pot that is in there, sometimes the Resistance value and taper are marked on the back of the pot.
  All that the circuit 'sees' is resistance values, it doesn't care where the potshaft is positioned, getting full sweep of resistance the circuit needs to see to go slow/fast therefore is not only governed by how far the treadle pedal gear actually turns the potshaft, Get a big enough pot on there and the pedal wouldn't have to be moved far at all to go slow/fast...
  However, if the pot has three connections, upping the value alot could have some other consequence...
  It shouldn't be too hard to get a treadle pedal to go all the way fast/slow as you're getting now, but how even the response is across the treadle travel...I did a Small Stone using Wah Case, and it took some re-do's to get the pedal to range the sweep speeds...I wanted and got less ratio of change with near toe down [faster settings], sacrificing a bit of super slow for a nice usable taper, up to pretty fast [I didn't really want the super fast SS "Space Wobble" on this one].
  Maybe the exact taper of the pot that's in there is about what you want, if it's 100k or so a wah pot would probably be workable...what exact taper again.
  That's why I keep harping to the wall about a treadle case carcass with a mechanism for StanDard Pots and PotShafts....how cool would that be, whip your wah, Volume, Phase, whatever the heck size/value/taper/dual ganged pot you can find in there and control it with your foot !!!
   
  GEO, "Secret life of pots' is a great read.

[scumbag]

I'm just checking out Secret Life of Pots now - thanks for the suggestion, it looks like a really good page. 

So, I could concievably just use a larger value pot, since only a portion of the sweep will be used - right?

[Mark Hammer]

The last thing you want the foot treadle to do is *force* the pot to rotate all the way.  The pressure applied at the very ends of rotation could easily damage the pot.  Consequently, all rack and pinion systems for pot movement plan around moving the pot less than it's full travel.

Because of that, setting up a wah properly involves positioning the pot and the pinion on it carefully, and picking which notch on the rack you want to use as your "start position".  You can often improve the feel of your wah by simply losening that little plastic foldover thing inside that maintains proper tension in the gear system, and turning the pinion on the pot over one notch (re-tightening the tension system once done).  What you want to make sure and avoid, though is having the pot rotate right to the very end when you press down the foot treadle fully.

[Roobin]

Have a look at RG Keen's article on making a wah pedal. http://www.geofex.com/Article_Folders/wahrocker/wahrocker.pdf

He points out that if you use a larger pot, and swep in a shorter range, the circuit only sees the resistance at the heel or toe down position. I know that doesnt make sense, so here's (hopefully) a better diagram to explain it.

NORMAL WAH

POT         0 - - - - - - - - - - 500k (or whatever it is)
TRAVEL   Toe - - - - - - - - -Heel

So the whole travel of the pot is used, but you have to sweep a long distance


DIFFERENT WAY

POT         0 - - - - - - - - - - 1M
TRAVEL    Toe - - - Heel

Note that travel only goes halfway along, so the max possible resistance is 500k.

Tailor to suit.

Credit must go to RGKeen and Maarten de Huu.

[scumbag]

Have a look at RG Keen's article on making a wah pedal. http://www.geofex.com/Article_Folders/wahrocker/wahrocker.pdf

He points out that if you use a larger pot, and swep in a shorter range, the circuit only sees the resistance at the heel or toe down position. I know that doesnt make sense, so here's (hopefully) a better diagram to explain it.

DIFFERENT WAY

POT         0 - - - - - - - - - - 1M
TRAVEL    Toe - - - Heel

Note that travel only goes halfway along, so the max possible resistance is 500k.

Tailor to suit.

Credit must go to RGKeen and Maarten de Huu.

Yes! That's what I was trying to explain... ok, I'm glad to know that will work. I'm just trying to get a bigger sweep for the same amount of travel. Thanks guys.