Real-time control over pedals is something that many players, myself included have always longed for and tinkered with. I used to own an EHX Hotfoot, when they came out in the late 70's.
They were nifty units that would let you turn a pot with your foot. The trouble was that they had so much torque that you could easily flip a smaller pedal over if it wasn't secured or heavy enough. As well, the adjustment to tighten the end of the flexible shaft around the pot shaft was so large that you were sort of constrained in what pedals you could use it with. You will note that the pot controlled in the video is on the
outside. EHX's primary planned use for the Hotfoot when it came out was really tinkering with the delay time on a Memory Man.
More recently, Tone in Progress came out with (and eventually shelved) their Third Hand controller, shown below. It was essentially a more compact version of the Hotfoot, with the cable mounted in a fashion that avoided the pedal-flipping and also permitted attachment in cramped quarters.
There are other even simpler means of playing the knobs with your feet, though without as much fine control. The Oknob and Vknob are examples of this.
Where the expression pedal is simply intended to provide a variable resistance to ground, one can simply use a photocell (LDR). When I learned that the Line 6 standard was simply a 0-10k resistance, I rummaged through my parts drawer, pulled out a photocell, affixed it to the surface of my guitar, between the bridge and volume pot, and covered/uncovered it with my pinky to "work" the Whammy pedal patch on my M5. In essence, I turned my pinky finger into a Morley pedal (which uses blockage of light to a photocell as their means of control.
Synth players have, for years, been using "breath controllers" to translate breath intensity into a control voltage. I have a little Yamaha CS-01 synth with a breath-controller input, like this one.
Finally, there are devices called
force-sensing resistors, that could be easily affixed to the top of a guitar, and used to control many pedals via their expression-pedal input; assuming the pedal uses a variable resistance to ground, as in the Line 6 standard. They come in a variety of shapes, sizes, and resistance values.
