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previous: R.G. Wah inductor source -- 8/25/1999 2:04 PM View Thread

Why-a-duck? Why-a-pot?

8/30/1999 4:33 PM
Mark HammerWhy-a-duck? Why-a-pot?
All this kerfuffle about pots and tapers is because when a pot is used as the control element, you're basically stuck with what the pot physically consists of - the conductive element and its value/taper are what they are and that's it (taper-altering resistors notwithstanding).  
Why not explore other non-pot alternatives?  
In the early 80's, there was a "pedal" called Patch of Shades, that used a force-sensing pad instead of a pot. Wierd-looking thing - sort of like a stompbox with a vinyl welcome mat out front, but it worked well from what I understand.  
It would be a modest (but feasible) amount of work to rig up a quasi-force-sensing pot by having a "see-saw" pedal with minimal travel (say 1/2 inch in either direction), that varied two force-sensing pads (one in the front and one in the back) made up from conductive foam. Go forward, and the front pad goes lower resistance as you press harder, while the rear goes higher resistance. Move your foot back, and everything goes the opposite way. Treat the jumper between them as a "wiper" and you're in business.  
The tricky part, naturally, would be selecting the right amount of conductive foam to provide the appropriate resistance.  
The operating/design constraints are that conductive foam gets, well, "crunchy" after a while (but a comfortably long while), and that there may be a wee bit of lag in registering "pot" changes, relative to a true pot.  
The good side is that you can custom tailor this type of pot to whatever value and taper you want (including multiple "ganged-pots" of discrepant values and tapers), and that when it wears/crunches out all you have to do is cut yourself another piece of foam (assuming you can still get it 10 years from now).

CJ Landry I want to say I have seen a pedal t... -- 8/30/1999 4:46 PM