how do these foot controllers work?

[Chico]

Does anyone know how the Line 6 expression/volume pedals operate in the Floorboard that works with the original POD?

It looks as if Line 6 uses a hinged pedal that transitions some sort of plastic or film band up and down.  A light sensor/reflectometer perhaps?  Magnetic sensor?

I am working on a project where I would like to have a foot controlled expression signal.  I need to eventually convert the expression information into a digital signal, so the first obvious approach I thought of is to use an ADC, apply a voltage across a pot  in an old wah or volume pedal and sample the wiper.

I already have the ADC in line (its built into a AVR microcontroller that is the heart of the project), so that may be the route I go, but I wanted to explore as many alternatives as I can.

Any other ideas as to how to create reliable and predicatble  (foot operated) variable signal suitable for sampling?


Thanks in advance

[puretube]

most probably a LDR-LED combination
(yes, and some ADC)