Hi, author here! Thanks for sharing this.
I'm in the process of making a introduction video for it but it's going to take a while.
In the meantime, I uploaded this short snippet for y'all to hopefully demonstrate how smooth and responsive the dials are: https://www.youtube.com/watch?v=PC_YKBjIinc
As much as I'd like more people to build it, I don't think it's a good match for your situation.
Both things that make the ottopot special (and thus a bit more involved and expensive) won't work with hardware synthesizers as far as I'm aware; 14bit CCs and MIDI feedback for updating the LEDs.
I think your best way forward would be to buy something like an Arduino starter kit with a handful of components and a breadboard and just start following some examples from arduino.cc — probably using USB MIDI at first because it doesn't require any additional components with modern microcontrollers. From there it's easy to go to DIN MIDI.
Overall I've found MIDI projects a very good entry into the world of electronics and microcontrollers because it's really simple and even the smallest projects can have immediate, motivating results.
Since the potentiometers are analog, they are advertising it as “theoretically infinite”.
I stumbled upon these endless pots by chance after looking at options to do something like this for years. I have experimented with optical mice sensors, thought about hall effect sensors and IMUs.
These pots do everything I wished for. Like I said in another comment, I think it's at a point where timing/MIDI bandwidth is factoring in more than the resolution.
And yeah, the reason why I never picked up a higher resolution encoder was just the price.
I was also thinking about the RP2040 for cost reasons, they are so damn cheap. But I'll go ahead with the Teensy and the PCB first before I'll try something like that.
> - do you have noise issues (as in a value oscillating by +/- 1 randomly)
I've implemented a dead zone logic for this: You have to move the pot a little bit before it “picks up” the movement. I think I've tuned this quite on the safe side and it still feels instant. I'm working on a video demonstration that will hopefully show it.
For testing, I was running some automation in Bitwig for an hour and did things like knocking on the table while it ran; if there was any CC message, it would take over the automation so after an hour I would have seen some green indicators to restore automation control.
> - do you see an issue in precision around your 0/max R positions? they are not exactly contiguous in the pot.
No, it feels very smooth. I had some issues with the logic for the points where the directions reversed, but after figuring that out, I can no longer tell where the 0/max positions are.
> - did you get a measurement of the angle equivalent for a change of 1 in your output value (equivalent of step angle in a step encoder)
No; it's analog and there's the deadzone logic so I don't think it is quite as simple as this, but since we're having 4096 values across 360 degrees it would be 0.09 degrees. I do believe that 12bit is actually a bit too much to be reasonable and it is probably more about the timing/bandwidth at this point, not resolution.
You are doing USBMIDI you can use
higher rate than normal serial midi, and you can have up to 16 parallel midi ports. Depending on how the tinyusb stack is configured on Teensy it may require tweaking it a little.
Author here, thanks! The issue with sliders is that either you'll have to use a “latch takeover mode” or use motorized sliders if the parameters change in the software. With these, the LEDs and internal values just update when something changes, so like a motor fader but much less involved and cheaper. I do agree that sliders better control but these dials with LED indicators feel like a better “general purpose” controller to me.
A couple of bits: 'course' -> 'coarse' and the reason you don't get the same feel from digital is simply because of the digitization itself, if the steps are large then there is always some movement that isn't enough for a whole step, rather than that it doesn't max out the full range.
Go with original replacement sliders from good mixer boards. They will usually be much much better and easier to select than any out of electronic vendor ones. They are really costly but the difference in behavior, feeling and reliability is worth the cost if you need precision.
I've had good success with Numark salvaged ones, but I'm sure there is better.
