Controlling guitar effects pedals with Arduino

Hello everyone. I am looking for broad suggestions about controlling guitar pedal parameters with Arduino. I am considering purchasing pedal kits, but hacking existing pedals is also an option.

What I want to do is to be able to change the various parameters, generally controlled by pots, from the Arduino. PWM? Optocouplers? Where to start!?!

Potentiometers can be wired in two very different ways.

If only 2 terminals on the pot is used, the pot is a variable resistor. There are serveral ways to substitute them. One woyld be a digital potentiometer. An IC that (usually) is controlled with some kind of serial data. Google digital potentiometers.

Another option would be a combination of a LED and a LDR (light dependent resistor. You wrap the pair up and control the LDR's resistance by varying the voltage going the LED, with for instance a PWM output.

If all 3 terminals are used the potentiometer is basically a variable voltage divider, these are more difficult to control.

Thank you very much MikMo, I will look into both of these options - I never would have thought of that LED/LDR combo, that is a great idea! Also had never heard of a digital potentiometer. Great stuff, thanks again!