madbeanpedals::forum

Projects => How Do I? Beginner's Paradise. => Topic started by: Bluestrat on February 14, 2012, 08:15:50 PM

Title: How do I replace a resistor with a pot?
Post by: Bluestrat on February 14, 2012, 08:15:50 PM
I want to replace a 470r resistor in a wah with a pot. What size pot should I use and how should it be wired?
Thanks!
Title: Re: How do I replace a resistor with a pot?
Post by: jkokura on February 14, 2012, 08:22:28 PM
Do you want internal or external control?

For internal control, you'll want to find a trim pot. 500 ohms. Connect one pad for the resistor to the middle leg, and then the other pad to either one of the outside legs. Doesn't matter which.

For external control, get a 16mm Alpha B500R pot, and wire one pad for the resistor to the middle lug (lug 2). Then wire the other pad to lug 3, the right side lug if the lugs are towards you and the shaft is pointing up.

Jacob
Title: Re: How do I replace a resistor with a pot?
Post by: Bluestrat on February 14, 2012, 08:36:55 PM

For external control, get a 16mm Alpha B500R pot, and wire one pad for the resistor to the middle lug (lug 2). Then wire the other pad to lug 3, the right side lug if the lugs are towards you and the shaft is pointing up.

Jacob

Thanks for the quick response. It's an external control. I want to be able to go both below and above the 470R value to adjust the gain on a transistor. Will the B500R allow for that or would I need a B1K?
Title: Re: How do I replace a resistor with a pot?
Post by: madbean on February 14, 2012, 08:52:22 PM
In that case use a 1k. Run a wire to lug3, solder a small resistor like 22R between lug3 and 2 and run a wire from lug1 back to the board. You'll get all the range you need +/- 470R and the extra resistor acts as a "stopper" when you have the pot all the way down.
Title: Re: How do I replace a resistor with a pot?
Post by: Bluestrat on February 14, 2012, 09:00:50 PM
Great! That's what I needed. ;D Thanks!!