Roland EV-5: I'd like to try

[wsnluca]

Hi, I'm Luca from Italy.
I'd like to try to build a Roland EV-5 expression pedal for my old Roland GP-8 guitar effects rack.
I found a schematic and I read I need 2 variable resistors 10K linear and 50K linear: is it right?

Which kind of variable resistor do I have to buy in particular? Can you suggest me any of these VR on Digikey.com website, please?

Any other tips or advices, please?

Thanks a lot!
Bye,
Luca

[wsnluca]

Anyone? 

[lvs]

Hi Luca - the 50K potentiometer sets the minimum expression amount and can be left out if you don't need that (see bottom diagram).

[wsnluca]

Thank you!
Which kind of pot do you suggest to buy?
I see there are many packages, many Watts and so on...
It would be really useful if I could see how this pedal is made: any pictures of inside? 

Thanks again! 

[lvs]

Sorry, I can't show a picture of innards because I don't have one. Maybe someone else will chime in.

The 50K can be a regular kind of pot like used in stompboxes.

The 10K is driven by a mechanism that rotates the shaft while the pedal is moved. For instance working like a wah-pot - have a look at the SmallBear site in the wah parts section. The pot should be able to do a lot of rotations without becoming noisy, or worn out inside the bushing too soon.

But I'm not speaking from hands on experience about this. I was planning to give it a try, and then noticed there are some cheap ones (some 25 Euro) around. The VP26U for example sold by MPM, Quiklok, Mutec and possibly a few other brands. Shouldn't be hard to find in Italy BTW. But don't let that extinguish your ambition to DIY one .

[Paul Perry (Frostwave)]

Any wattage will be OK.
The pot in the EV-5 is linear, NOT log (log is the kind used in audio volume controls).
Make sure you get a pot that you can replace when it wears out.