1/23/2026 - Ideas + First Schematic

This project has been on my mind a while, and since blueprint got extended AGAIN, I might as well!

The Idea

If you've ever heard of Deej, this is a similar idea. In fact, I have a Deej-powered board sitting on my desk right now. Basically, it's just a bunch of potentiometers you can configure to change the volume of any applications on your computer, individually. It is very crude right now, and is unfortunately buggy and sometimes hard to use. My idea is to replace it with a spiritual successor, that is configurable in a similar way, but made more robust and extend the functionality of it.

My Deej has 5 linear potentiometers (that are actually logarithmic, but shush), and that's about it. I want to go more advanced and make a PCB for it to keep the components well in place (my current one is literally held together with tape. not kidding), and drastically simplify the wiring required (I am scared to open my current deej as it is more than a rat's nest in there). Anyway, this will also allow me to add some complexity.

To start, I'm ditching the sliders in favor of rotary encoders, with switches. This will make the design more compact and sleek, as well as adding an option to completely mute with the switch. Previously, when the sliders are fully down, they bug out and most of the time don't silence it all the way, so this will be a good improvement.

I've always been a sound techie, and I am very familiar with a couple different sound mixing boards. I want to make it a tad more similar to those, so I decided to add 20 different LEDs to show volume levels and live sound levels coming from the computer. These will be lined up in columns next to each rotary encoder to show what sound is coming from that application, as well as one more above the encoder to show the current volume of that app. On the master encoder (controls entire computer volume), there will be two columns that show L and R outputs. Trust me, it'll look good.

The microcontroller I've decided to go with for this project is a RP2040-Zero. This thing is smaller than 1x1in, and has 20 GPIOs for me to use. Basically everything I need, nothing I don't. I plan on using circuitpython just to simplify the firmware side to focus more heavily on the software that runs on the computer.

Schematic

Here it is!

Obviously subject to change. There are 3 different "channels" of LEDs, just to simplify the firmware more.

BOM

Very unofficial right now, but here's my Aliexpress cart:

You may notice I'm splurging for some really nice aluminum knurled encoder caps, they will make this feel like a real product instead of a hobby project. (not that that's a bad thing)

Anyway, see you when the routing is done!

1/24/2026 - Routing, Change of Plans

While I was routing, I noticed that it didn't look particularly good with only 4 encoders, as the PCB isn't wide enough to accommodate them and the LEDs. So I added another encoder!

I have also rearranged the LEDs so that each encoder gets 3 to show the current volume level. Unfortunately, just looking at other software examples, I couldn't find a good way to just get the current peak volume from an app. This is a corner I'm willing to cut, but the master encoder still has it's peak level LEDs.

This was actually my second time around routing the PCB. The first one was a complete mess and I never want to look at that again.

I decided to put the ground fill on the top layer, as that's where the LEDs are, so they can benefit from it too. Otherwise I would stick it on the back layer and call it a day. I likely will end up rerouting this again, as the pinout locations kinda blow.

Anyway, next step is CAD! (actually not that excited but here we are)

2/15/2026 - CAD, Firmware, BOM, review!

The CAD is done! I had a little bit of struggles with this one but it turned out really well!

I took all the experience I gained from my other 2.5 projects and did the best I could. It was a little jank but it turned out just fine.

The hardest part is getting the tilt angle I wanted; there wasn't a clean way to do it in Fusion and I outsourced some help (that didn't really help)

After a while I just made another sketch on the side to make a different extrusion to fill the space.

The firmware is very basic right now, it does everything it technically needs to to function, which is take the rotary encoder information and send it along the serial port and vice versa to receive data.

The BOM is relatively simple; just 4 items, totaling under $25.

With that, it should be ready for review!