Simple Expression Pedal Shematic

  • Thread starter Thread starter marshall409
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marshall409

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So I'm stuck right now with using a Digitech RP-50 which has inspired me to blacklist Digitech from my future purchases. but oh well, it will have to do. what could make it better is taking advantage of the expression pedal capabilities of it. The digitech website says

"Expression Pedal
The rear panel of the RP50 includes an input for an expression pedal. Any passive volume pedal can be used as an expression pedal with the RP50. Connect from the output of a passive volume pedal to the Expression Pedal Input on the RP50. The expression pedal controls the RP50’s Volume,Wah, or Whammy™ parameters. If Wah and Whammy are disabled, the expression pedal functions as a volume pedal. If the Wah or Whammy™ effects are enabled, the expression pedal control these effects."

So I decided i wanted to try the whammy and wah effects to see if they are decent at all. but i realized that a passive volume/expression pedal must pretty much be just a pot controlled by the pedal rocking. So how hard could that be to build right? well, i googled, and googled and googled and found the attatched image. success! but wait, i looked at the radio shack website. what kind of pot am i looking for? Linear? audio? Tapered? Volume? Gah! any help? I am wondering what kind of pot i need and a suggestion on the ohm rating. i read somwhere that commercial wahs/volumes/ use about 100k. does this sound right? and lastly, is it as simple as it sounds or am i completely missing something? thanks alot.

Adam
 

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i think you could start with any pot in the 100k to 500k range

experiment with tapers to see what works best
marshall409 said:
So how hard could that be to build right?
the problem is mechanical - how to make a pot turn round or a slider go back and forth, coupling it to a pedal going up and down and making it smooth and long lasting

your best bet might be to find an old volume or wah pedal and modify it if necessary

starting from scratch is considerably more difficult
 
thanks cannabis. I've read about the mechanical part and thats the part that interests me. those kind of challenges are the ones i enjoy most, i just wanted to veryify the electronic part before i went in to the trouble of building it. also, ive read about using wacky substitutes for the housing, such as a sewing machine pedal. that would be pretty cool to me.

Adam
 
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