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So, I looked into digital potentiometers recently, and realised that I could take an Arduino, send a control voltage out to an expression/volume pedal, read the return voltage from the sweeper, and use that plus toggle switches to control individual channels of the digital pot...

Long story short I'm gonna make a pedal that can use one volume/expression pedal to control 6 individual CVs/volumes. Even cooler is I could potentially expand into midi control of Control Voltages for other pedals, or even sequencer control of the same...

Hopefully by posting this I'll actually be forced to follow this through, unlike most of my other projects. I'll make sure to take pictures/videos and let everyone know how it goes

Awesome dude. Defo share some updates on your progress

Oooh sounds cool, I know someone has a kickstarter for a device that attaches to pots to control them like this, replaces the knobs I believe, but actual digital pots would be cooler

Yeah, i know what you're talking about This will be the same as connecting an expression pedal up to an expression input basically, except you can connect one expression pedal up to 4 pedal expression inputs instead! Should make my setup easier to control, and also more compact

Actually JB, I bet you using digital pots is how you had presets on your fuzz factory clone! If this goes well, I might consider doing rehousing+preset mods for analogue pedals...

You could do some cool things as well, like customisable tapers and auto-sensing

Just ordered 10 Stereo jack sockets from a chinese seller on ebay for about $6. I would have liked to use switchcraft sockets, but they're above $5 EACH :S

Next step is the 6-channel digital potentiometer. I'll be using an AD5206BN10 chip.
This chip includes 6 individual digital 10k pots, with 8-bit resolution (256 resistance steps). I think this should be enough, considering it's essentially 40 ohm steps. If i want to emulate logarithmic pots (for volume) It might not be enough though... We shall see.

Most other parts I already have (Arduino nano, single colour LEDs, Hammond 1590BB enclosure, various resistors) so once I order the digital pot chip I should be good to go

I might have to look into a larger enclosure though, i'm not sure if there'll be space for 9 jack sockets and power (4xTRS for expression pedals, 4xTS for In/Out for stereo volume, 1xTRS for expression pedal input) but we'll see, i'll mock up positions of components once I get the jacks.

Sick dude, keen to see how this goes!

I follow also with interest, have a related aduino controlled pedal on the bench, reading around warned against digi pots in audio circuits, preferring aduino controlling octocouplers. Ymmv I can't wait to hear you results. Is the nano the one with seperate programming board? That's the way I went, in the future (hah) I thought I'd go just the throughole chip on its own.

Interesting about the audio circuits and digital pots thing, i might have to look into that a bit more. Either way, if I only use it for expression inputs that's fine

The nano is still programmable through a mini-usb connector luckily. I am planning to solder directly to the through holes rather than using headers simply because the microprocessor board was so cheap anyway and I won't be planning to change anything once I've set it up.

Nice, if it does work out consider the pro mini for future projects. You have to buy a seperate USB board, but only once, the combined cost looks the same as the nano. Plus the pro mini can save space inside.

Alright, slight change of plans. For some reason I didn't think about the fact that the digital pot would be limited by the supplied voltage (meaning i'd have to bias the guitar signal and then you get noise from the voltage divide changing the bias point as you change the pedal position) so I'm looking into an opto-coupler setup based on this circuit:


And controlling the attenuation using pwm.

Does mean more money on ICs though