Replacing potentiometers with digipots on a fuzz effect pedal

Other Hardware General Electronics
1

Hi all,
I have a fuzz guitar effect pedal kit to build. I would like to replace its knobs (potentiometers) with digital potentiometers and control them with Arduino using SPI. Arduino coding and SPI implementations are more or less clear for me, but the problem is to find right digital potentiometers or some other solution to replace the potentiometers.

See the original fuzz diagram here.

The potentiometers to be replaced are:

  • P1: C5K
  • P2: A500K
  • P3: A250K

5K digipots are manufactured widely and 250K digipots with SPI can be found few. However I'm not able to find 500K digipots with SPI on the market. Are there such digipots available somewhere? Is there some other work around to replace the 500K potentiometer?

Thanks!

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2

Just checked Mouser and RS. An alternative would be the use of i.e. H11F1M. These are linear optocouplers. Using the Arduino with PWM to control the optical side and using 2 in series. Would give you 255 positions after a lot of research though.

3

What if I put two 250K digipots in series?

4

What if I put two 250K digipots in series?

Then you'll have two center-taps with neither center-tap covering the whole range.... One 250K should be fine.