anaQuad120 was mentioned in a previous log entry, here: https://hackaday.io/project/9984/log/33419-anaquad120 wherein a couple hall-effect transistors from a BLDC-motor can be used as an encoder. In the previous log, I used those from a 5.25in floppy drive. But there's a better source, and these could be easily used as a dial for most purposes...

OK, so this is the spindle-motor from a DVD-drive. You can clearly see the hall-effecttransistors. Awesome. This guy wants to rest in something like 36 positions per revolution, but isn't nearly as "snappy" as the floppy-drive's spindle-motor. I haven't rigged it up yet,it just occurred to me, and it's a bit difficult to follow the traces under the motor. But, definitely doable, and its size/shape is highly-conducive to being used as a dial such as a volume-control or something.

So, again, anaQuad120 allows for treating a system like this much like a quadrature-encoder. Most quadrature-encoders meant as dials are only 16 "detents" per revolution and cost around $3 apiece, so here's a source for 36-position encoders :)

There exist hall-effect sensors that output a digital signal... so it's possible that's the case, here, in which case anaQuad isn't necessary... regular quadrature-decoding would probably work (despite they're most-likely 120deg out of phase, rather'n 90deg). But, judging by the fact these sensors are 4-pin rather'n 3-pin, they're probably analog-output... and anaQuad would work happily with that, and likely increase the resolution from 36 positions per revolution to (was it 12x?) a few hundred (if somehow that's useful...).

Another thought, especially on the higher-resolution, this shaft could be attached to a motor's... And then you've got a few hundred positions per revolution.