> any jack can have a knob plugged into it to set it to a fixed value.

I'm kind of surprised he didn't start with a knob with a tiny accelerometer, mcu and battery in it to produce some sort of output signal into a stock plug depending on how the knob is oriented with respect to gravity.

Putting electronics inside the plug is nearly a mitxela trademark. https://mitxela.com/projects/flash_synth

I was wondering this - I'd buy this if I could just plug it into my existing sockets. I'm pretty sure you could get 50-100 hrs with a battery, but I wonder if you could have something that you wind-up like a mechanical watch.

Profit margins on eurorack are pretty damn low. And you need a lot of knobs and jacks and plugs. Even a hall effect sensor may be out of the sweet spot for cost.

Probably because pulling on cords can twist them. That’s what I thought when this occurred to me.