Eurorack Knob Idea

Summary

Eurorack Knob Idea24 Apr 2025Progress: Complete Last year I designed a eurorack module, as a collaboration with Dave Cranmer. When I say designed it, I mean we got about 90% of the way there, then got distracted. With any luck, that module will get finished and released sometime soon. But it had me thinking about Eurorack and the weird compromises people often make to fit more and more modules into a tiny case. I know a thing or two about tiny synthesizers. But my creations are often whimsical and useless. When it comes to Eurorack, where people spend crazy amounts of money on their setups, it's weird to see people compromise on the main aspect that gives it an edge over simulating the whole thing in software. To clean up our Eurorack panels, perhaps we need a new knob idea? Watch the following video for a prototypical demo. VIDEO In essence, we're using a 3.5mm jack in front of a magnetic encoder chip, and a small magnet embedded in the plug turns it into a knob and patch cable hybrid. The magnetic encoder in question is an AS5600. These are not the cheapest parts but they do make prototyping very easy. It has two hall sensors in an XY configuration and a dollop of DSP to give us an angle and a magnitude. They're easily available on breakout boards and have an i2c interface. The board also comes with a specially polarised magnet with the field across the diameter instead of axially. We're not going to use that. Building the knob I started by taking a dremel cutting disk to the end of a TRS plug. This was just done by eye. Edge-on, it's not quite centred but it'll work fine. This cheap plug is in fact partially hollow, and is made from plated brass. Into this slot I glued a small neodymium magnet. It's 2mm diameter, 1mm thickness. I also bought some 2mm thickness magnets, but that would need a slightly wider slot, which would probably require a more precise cutting method. I used a medium viscosity cyanoacrylate glue. Once set, the excess can be scraped away with a ...