I am on a quest to make my analog line mixer (4 audio input channels with pots, 1 output channel to amplifier) remotely controllable. So I want to control the pots via Arduino.
I was about to order motorized faders. So Arduino could control the motor and the faders replace the pots elektrically. But it needs to work in stereo. These faders have usually one resistor channel for servo feedback (read the position of the fader through AD input) and sometimes a second channel for doing the potentiometer function. Sure I can use both for the audio L+R channels, but then I am missing the position feedback. Unless someone knows a way to both use it for feedback as well as for audio. But my hardware level is too limited to come up with such a design (I dont think it is possible).
I also considered doubling the amount faders (with double channels). That will do the trick for sure but gets me 10 motors (10x H-Bridge), 10x touch input (2 GPIOs) and 10x AD input only for this. It is getting way to big and expensive that way. There must be a more simple solution, right?
So maybe someone knows a way to make a digitally controllable equivalent of a potentiometer? Aren't there I2C/SPI IC's that make a resistor value based on digital input or something? or maybe someone know a way to read a resistor value while at the same time using it for audio level control.
Original intention was to re-purpose an existing line mixer by replacing pots. I am also willing to make my own mixer design. My skill level is expert on software and basic on digital electronics and limited on analoq elektronics. I'm able to understand and design PCB's from existing schematics.
let me also pits my project. Controlling audio inputs digitally has great advantages! I am hooking it up to my home automation system. So I can automate input levels of different audio channels based on request scenes. Also lot's of fancy tricks can be thought of when using motorized faders just as an input for Arduino. For example assign different functions to one fader: balance, volume, channel and even controlling light levels of other home automation lights. So endless possibilities. If only I knew how to control audio levels via an Arduino....