[sdiy] Question how to improve rotary encoder feel

[Ben Bradley]

I'm trying to send this a second or third time, my last attempt made
it to the list but may have looked like an empty post.

I've thought about this for a while. The readily available/cheap
encoders give 12 to 24 pulses (or rest positions - they generally go
through the whole 4-transistion quadrature sequence for each position)
per rotation, so take many turns to set a value with reasonable (128
or 256 position) resolution. I noticed in the late 90s the HP and Tek
equipment had nice high-resolution optical encoders, butsuch encoders
were $30 range, and still are. They're good and "affordable" if you're
going to use one incremental encoder that is switched between all
functions:

https://www.digikey.com/product-detail/en/bourns-inc/ENS1J-B28-L00256L/ENS1J-B28-L00256L-ND/1089392

I've had the idea of using two analog hall-effect sensors mounted ad
right angles to detect the rotation of a magnet on the end of a shaft.
They'll give a sine-and-cosine output of shaft position that you can
run into the DAC of a microcontroller and use an arc-tangent function
to get the shaft angle. With a little multiplexing, a single
controller can read many shaft positions simultaneously (okay, fast
enough to appear simultaneous). I was hoping I was the first to come
up with the idea, but I saw it mentioned in the SDIY archives maybe
six years ago.

I've got a few DRV5053 from TI, they're cheap enough at a dollar each.
and about $0.50 for higher quantities. There are several models with
different suffixes indicating different magnetic sensitivities:
https://www.digikey.com/product-detail/en/texas-instruments/DRV5053RAQLPGMQ1/296-40066-1-ND/5177943
They're available in SMT but to use them this way you'd have to mount
one on each of two PCBs, and set the PCBs at a 90 degree angle to
sense the field.

I saw this video a few months ago, he says these are the only two
prototypes of this synth. I think this is a great interface, it's the
ultimate as far as any ideas I have. Each function has its own knob,
and the horizontal LED bar (that goes across the whole front panel)
shows the value of the control when you touch the control, and varies
as you turn the control. I wonder of each of those controls is one of
those expensive optical encoders:

https://www.youtube.com/watch?v=xiV7lzYuM8I