[sdiy] Using dual taper (4 pin) pots as encoders ?

[Benjamin Tremblay]

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Here is a photo of the syntaur part for a Novation circuit encoder. It is a 10k potentiometer.
Benjamin Tremblay

> On Jun 21, 2024, at 3:26 PM, brianw <brianw at audiobanshee.com> wrote:
> 
> Thanks Martin and Roman. It's always interesting to learn about unique parts - especially when actual part numbers are shared.
> 
> Brian
> 
>> On Jun 21, 2024, at 6:11 AM, Martin Klang wrote:
>> aka Endless potentiometer, with two outputs in phase quadrature. The Alpha RV112FF-40 is the only commercially available example that I know of.
>> 
>> Martin
>> 
>> -----Original message-----
>> From: Roman Sowa
>> Sent: Friday, June 21 2024, 2:53 pm
>> 
>> Quadrature potentiometer.
>> One taper is rotated 180 or 90 degrees versus the other one. This way at
>> any angle there's at least one wiper on its taper. Basicaly a way to
>> remove the dead spot, where wiper travels over empty fragment between
>> taper ends.
>> Measure 2 voltages, a bit of calculations and you have rotary encoder
>> with resolution as high as your ADC.
>> 
>> Roman
>> 
>> W dniu 2024-06-21 o 13:34, Benjamin Tremblay via Synth-diy pisze:
>>> Hi, another MCU question.
>>> I have noticed many synth manufacturers have used 10K 4-pin dual
>>> potentiometers as “encoders”. I’m assuming that these are feeding a
>>> multiplexed ADC.
>>> My question is, what is the secret sauce? Are both pot tracks wired
>>> differentially to reduce noise? Does this indeed go into an ADC or is
>>> this some clever way to approximate a rotary encoder but have the smooth
>>> motion of a pot?
>>> 
>>> If using a 4-pin potentiometer is a way of achieving a more stable and
>>> reliable mass-production of control knobs, I’m very interested.
>>> 
>>> Thanks,
>>> Ben
> 
> 
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