Expression pedal that works on the pot !!!

[AM]

Hi people,
I've seen this sometime ago and thought it was a good idea.
www.toneinprogress.com
http://guitars.musiciansfriend.com/product/Tone-in-Progress-Third-Hand-Expression-Pedal-?sku=150146

An expression pedal that works on the pot. That should come handy in certain situations. I have a wah/volume case sitting around with an old 25k pot that maybe could be used for a similar expression pedal. Does anybody know how I could make a pedal like this? I have some drawings of normal expression pedals and I would think it is probably based on the same principle. Any ideas?

[ppatchmods]

I'm not sure of the mechanics, but I think the cable is a brake cable from a car. Not sure of anything else.

[ayayay!]

It's a ridiculously simple idea, but the design took some thought I am sure.  I think Paul Gilbert uses one.  I don't know if it's a brake cable per se, but it's some kind of cable that is compressed enough to twist each end simultaneously when cut to short lengths like that.  The radius has a lot to do with it.  Making that arc is prime for turning, so if you have an effect with top mounted knobs (which is 9 out of 10 of them out there) you'll want your foot controller to have that cable on top as well. 

To me the trickiest part will be those end assemblies:  The "boot" if you will, with a set screw that snugs the shaft of the pots nicely and isn't off-center by too much, in combination of the cable feeling fluid when rotating. 

[earthtonesaudio]

I was thinking it was a speedometer cable, but who knows...

Any "rocker" foot pedal is a small engineering feat by itself.  It has to be small, rugged, precise, smooth, and comfortable.  But if you already have a wah shell you're partway there.

On top of that, doing what this pedal does would be even more difficult, but that doesn't mean it's not DIY-able.

First, decide how much travel you want for your foot
Then, decide how much you want to be able to turn the pot (100% or less, maybe some way to prevent damage due to over-turning)
Then figure out how to translate back and forth of the foot into rotation of the cable (gear ratios...)
Then figure out how to make that cable...

Good luck!

[AM]

Yeah the "brake cable" thing came to my mind too. It reminds me the cable of my bicycle's brakes.  Though I really doubt it works in a similar fashion...
As I said I have some wiring diagrams of different expression pedals but that cable thingy is something that I haven't figure out how it works yet

[sean k]

If we take for granted that they've been very clever dealing with a normal way of doing things then we would have a quite tricky and time consuming set of problems to overcome but we don't have to make our pedals with the pots orientated upwards so immediately what we want to acheive might become alot easier. If we mount pots on the side of the enclosure then they are in the same plane as the traditional rocker shaft in a wah. Then it makes it much simpler to create a shaft that possibly wouldn't even need the outer sheath and would only need fittings either end. Or you could just use the sheath or casing which might be easier to make fittings for.

[AM]

If we mount pots on the side of the enclosure then they are in the same plane as the traditional rocker shaft in a wah. Then it makes it much simpler to create a shaft that possibly wouldn't even need the outer sheath and would only need fittings either end. Or you could just use the sheath or casing which might be easier to make fittings for.

I agree with you. I was actually trying to figure out a way to do it without having to mount the jacks on the top and just use the holes on the sides of the wah enclosure. Similar to the way I would wire a normal expression pedal.

[aron]

EH did this years and years ago... Good idea

[vondran]

Here's an alternative approach <http://www.optionknob.com/>.  It may not satisfy your needs, but I'm figuring I may rig up something similar from what I can find at Home Depot.  I'm only looking at being able to occasionally adjust the effect level on a delay pedal, so an expression pedal is over kill.

[AM]

Here's an alternative approach <http://www.optionknob.com/>.  It may not satisfy your needs, but I'm figuring I may rig up something similar from what I can find at Home Depot.  I'm only looking at being able to occasionally adjust the effect level on a delay pedal, so an expression pedal is over kill.

Hey, thanks man! That might actually do it. I'm looking for nearly the same thing as you do  I occasionally want to tweak the delay time knob of my pedal while playing. I'll try to  rig up something like this too and see how it goes. If it works it might be an even better solution than the expression pedal since it wouldn't take any extra space on my pedalboard (which I always keep at minimum possible size).

[Paul Perry (Frostwave)]

Don't forget the dremel flexible drive..

[aron]

Of course I also use the MXR knobs that allow you to adjust the knob with your foot.

In the store link above. :-)

[AM]

Don't forget the dremel flexible drive..

Yeppppppp.......that's the thing Thanks Paul.

Of course I also use the MXR knobs that allow you to adjust the knob with your foot.

In the store link above. :-)

Aron, that was my first thought a long time ago. Unfortunately there is not enough space between the pot shafts to fit the MXR knob