[sdiy] Using dual taper (4 pin) pots as encoders ?
Mike Bryant
mbryant at futurehorizons.com
Fri Jun 21 17:32:32 CEST 2024
I notice the Alpha part only has 15000 cycles. Okay for an equaliser control but if people start madly spinning these round like they do the digital ones you'll soon get there.
________________________________
From: Synth-diy <synth-diy-bounces at synth-diy.org> on behalf of Benjamin Tremblay via Synth-diy <synth-diy at synth-diy.org>
Sent: 21 June 2024 15:58
To: Tom Wiltshire <tom at electricdruid.net>
Cc: Martin Klang via Synth-diy <synth-diy at synth-diy.org>
Subject: Re: [sdiy] Using dual taper (4 pin) pots as encoders ?
Yes Roman! That must be it.
It’s not what I would think of as a “stereo panpot” with six leads.
And how would I shop for one)
Benjamin Tremblay
On Jun 21, 2024, at 9:29 AM, Tom Wiltshire <tom at electricdruid.net> wrote:
I hope the mounting height matches some other useful hardware!
Trying to find pots that match the rotary switches, encoders, or buttons you have is very difficult.
Tom
On 21 Jun 2024, at 14:11, Martin Klang via Synth-diy <synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>> 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 via Synth-diy <synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>>
Sent: Friday, June 21 2024, 2:53 pm
To: Benjamin Tremblay <btremblay at me.com<mailto:btremblay at me.com>>; SDIY List <synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>>
Subject: Re: [sdiy] Using dual taper (4 pin) pots as encoders ?
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
>
>
> Benjamin Tremblay
> btremblay at me.com<mailto:btremblay at me.com>
> Carlisle, MA 01741
>
>
>
>
>
>
>
>
>
> ________________________________________________________
> This is the Synth-diy mailing list
> Submit email to: Synth-diy at synth-diy.org<mailto:Synth-diy at synth-diy.org>
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________________________________
From: Synth-diy <synth-diy-bounces at synth-diy.org> on behalf of Benjamin Tremblay via Synth-diy <synth-diy at synth-diy.org>
Sent: 21 June 2024 15:58
To: Tom Wiltshire <tom at electricdruid.net>
Cc: Martin Klang via Synth-diy <synth-diy at synth-diy.org>
Subject: Re: [sdiy] Using dual taper (4 pin) pots as encoders ?
Yes Roman! That must be it.
It’s not what I would think of as a “stereo panpot” with six leads.
And how would I shop for one)
Benjamin Tremblay
On Jun 21, 2024, at 9:29 AM, Tom Wiltshire <tom at electricdruid.net> wrote:
I hope the mounting height matches some other useful hardware!
Trying to find pots that match the rotary switches, encoders, or buttons you have is very difficult.
Tom
On 21 Jun 2024, at 14:11, Martin Klang via Synth-diy <synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>> 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 via Synth-diy <synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>>
Sent: Friday, June 21 2024, 2:53 pm
To: Benjamin Tremblay <btremblay at me.com<mailto:btremblay at me.com>>; SDIY List <synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>>
Subject: Re: [sdiy] Using dual taper (4 pin) pots as encoders ?
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
>
>
> Benjamin Tremblay
> btremblay at me.com<mailto:btremblay at me.com>
> Carlisle, MA 01741
>
>
>
>
>
>
>
>
>
> ________________________________________________________
> This is the Synth-diy mailing list
> Submit email to: Synth-diy at synth-diy.org<mailto:Synth-diy at synth-diy.org>
> View archive at: https://synth-diy.org/pipermail/synth-diy/
> Check your settings at: https://synth-diy.org/mailman/listinfo/synth-diy
> Selling or trading? Use marketplace at synth-diy.org<mailto:marketplace at synth-diy.org>
________________________________________________________
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