[sdiy] suggestions for foot control

[Gene Stopp]

Yah I was about to chime in about the radio tuner method (also used in some Wurlitzer organ volume pedals). Hammond B3's used multi-plate variable capacitors (tough to do in a pedal, and tough to do with op-amp voltage levels) and Hammond BV's used a ladder of spring contacts with a resistor ladder, with a phenolic wedge that went in and out with the pedal. Some church organs used a wooden drum with a diagonal wire on the outside, and a bunch of j-wire-like-things from a resistor ladder laying on the drum. The world's first zipper noise! Also in pedals I have seen a cam on the pot shaft with a long slot in it, and a lever from the pedal with a peg on it that slides in the cam's slot. Most of these mechanical pot tricks don't move the pot thru its full rotation, so there's always some loss in the resistive divider. One problem with the rack-and-pinion method is how to keep the rack from poking thru the bottom of the pedal in the full forward position.

The advantage to using a mechanical solution is that it's totally passive.

- Gene



-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of harry bissell
Sent: Friday, June 16, 2006 12:55 PM
To: Spencer Johnson
Cc: synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] suggestions for foot control


Ernie Ball made a volume pedal that that used a cord (like the dial cord in
an old analog radio tuner) wrapped around the pot shaft.

It really worked well,,, the only thing that would break would be the 
string.
I copied the idea and added a couple of pulleys to change the rotation
plane to control the speed of an MXR Phase 90... too cool

H^) harry


Spencer Johnson wrote:
>> The MoogerFooger foot controls are just a foot pedal controlled pot.
>> They come with a 1/4" TRS jack going to the three terminals on the pot.
>> I think the pot is a 50K.
>>
>
> as far as this pot goes, whats its action of control? i mean, how does
> it transfer linear motion to rotation motion? just a set of gears?
>
>