minimal Deej volume mixer

deej is an open-source hardware volume mixer for Windows and Linux PCs. It lets you use real-life sliders (like a DJ!) to seamlessly control the volumes of different apps (such as your music player, the game you're playing and your voice chat session) without having to stop what you're doing. The project can be found here.

I wanted to go for a more minimal design of the case as I want it to be as least distracting as possible when it's sitting on my desk. That's why I haven't added any kind of logos or little pictures next to the knobs. It also allows me to remap the knobs without having to print a new front plate. The leftmost knob is the one controlling the master volume and it is distinguished by color to indicate that.

The knobs are not made by me. They are from here and have been equipped with an indicator by adding a negative volume (see Assembly).

Bill of Materials

1x Arduino Nano Every (others are usable but this one fits the case best)

4x Potentiometer

I have used these (german shop). The resistance should be anywhere between 3k and 50k-ish. Refer to project page and arduino documentation. Important for assembly is that the poti has similar dimensions to the ones shown in the image. Especially the M10 threading, the 9mm length of the threading, the 8.8mm flattened part and the 6mm diameter of the axle are important.

4x M4x8 countersunk bolts and nuts each

The nuts are press-fitted into place. The allen key for tightening the bolts works well for pushing the nuts all the way in!

weights

I have used the nuts and washers of the potis plus two M8x60 bolts to glue into to the case to add some weight.

4x rubber feet

PLA is pretty slippery…

Wire

Printing

1. Print both case parts (Case and Front plate) once 
2. Print four knobs. You can get the stls for the knobs here. 
   • You then have to add a negative volume Box that is 1x20x1mm and move it to the right position: Flush with the build plate, one end sticking out of the knob, the other end (almost) dead-center with the knob.
   • You can freely choose the color of the knobs and either do it like me or try matching the knob color with the app color (Spotify = green, Discord = blue/purple, etc.)

Tools

• Allen Key 2,5mm
• Soldering Iron including electronics tols (wire stripper, wire cutter, tweezers, solder, etc.)
• Hot Glue Gun
• Small Saw and optionally Sandpaper to shorten the poti axle to required length

Assembly

1. Shorten the poti axles to 11mm (10mm is fine too but the knobs will be in contact with the front plate then)
2. bend the poti pins away from the axle so they fit into the case better
3. push the potis into the front plate. On my machine it was a pretty tight press-fit as the threading grips the layer lines pretty well. Optional: Apply hot glue to the potis to secure them. I didn't do that with mine and it works well.
4. Push the M4 nuts into the four slots
5. Solder the connections (I assume you know how to handle a soldering iron and if not, this is a nice project to dip your feet into the topic)
   • Make sure you have enough wire between the potis and the Arduino to be able to glue the Arduino into the case without the front plate obstructing the hot glue gun
   • Make sure that the wire will fit into the case. Soldering the wire in an angle that makes it stick out a lot will make it more difficult to insert your assembly into the case
   • I connected all the 5V and GND pins of the potis together and only had two wires to the Arduino then. Makes it a little less messy
6. Glue the arduino into place using the hot glue
7. Glue the weights into the case
8. Close the case and secure with four bolts
9. Add the rubber feet

I hope you enjoy my model as much as I do and I would love to see a make of it!