[sdiy] sin/cos pot

[Ullrich Peter]

Hi!

Muxing 6 pots would be an easy task. As you don’t move pots very fast simple single channel multiplexing
would be enough, so for 6 pots with 2 pot channels per pot a 4067 16 channel analog mux would be suitable.
For breadboard prototyping you can buy this chip mounted on a little PCB for about 2€
https://www.wish.com/c/58c635b50b362f70debbcbf1

If you have a dual channel synchronous sampling ADC then you could take two 4051 analog muxes.
Prototyping PCB:
https://www.banggood.com/CJMCU-4051-74HC4051-8-Channel-Analog-Multiplexer-Module-p-1091944.html?rmmds=search

Ciao
Peter

Von: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] Im Auftrag von Bruno Afonso
Gesendet: Montag, 10. Juli 2017 20:28
An: Liam D <helloliamdaly at gmail.com>; Rick Jansen <rick.jansen at xs4all.nl>
Cc: synth-diy at synth-diy.org
Betreff: Re: [sdiy] sin/cos pot


How do these feel? Like previous generation elektron encoders? Could we easily mux 6 pots into one ADC? I've never done it. I have a teensy 3.6 based prototype to send out dmx where I currently have 6 encoders. But I'd love to upgrade this to elektron like encoders/endless pots.. :) this is exactly why a while ago I asked about it. Others were interested as well.

On Mon, Jul 10, 2017, 13:47 Liam D <helloliamdaly at gmail.com<mailto:helloliamdaly at gmail.com>> wrote:
Thanks! I remember coming across this style of pot a while back when tinkering with an alesis ion. That synth used about 30 of these plus a few regular pots all muxed down to 8 ADC channels. The service manual is on the web if anyones interested in the schematic. I always thought these would be cool parts to design with but I could never find a supplier for them.

cheers,

Liam

On Jul 10, 2017, at 9:50 AM, Rick Jansen <rick.jansen at xs4all.nl<mailto:rick.jansen at xs4all.nl>> wrote:

Very useful! Thanks for this, I had never seen it before.

rick

On 10 Jul 2017, at 13:12, Ullrich Peter <Peter.Ullrich at kapsch.net<mailto:Peter.Ullrich at kapsch.net>> wrote:
Hi!

Maybe the Bourns ACE Encoder could fit here: absolute encoder, 128 states per revolution, no hard steps
https://www.bourns.com/pdfs/ace.pdf

about 5pounds
http://uk.farnell.com/bourns/eaw0j-b24-ae0128l/encoder-rotary-128pos-8-bit/dp/9358234

Youtube:
https://www.youtube.com/watch?v=MrPW8QGmlrM

https://www.youtube.com/watch?v=44-XMo730wI


Ciao
Peter

http://www.ullrich.at.tt<http://www.ullrich.at.tt/>       (My homepage)
http://synpro.heimat.eu/datadial.htm   (Synth addon)
http://rc100-usb.at.tt/    (Roland sampler tool)



Von: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] Im Auftrag von paula at synth.net<mailto:paula at synth.net>
Gesendet: Montag, 10. Juli 2017 12:51
An: Julian Schmidt <elfenjunge at gmx.net<mailto:elfenjunge at gmx.net>>
Cc: synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>
Betreff: Re: [sdiy] sin/cos pot


Issues I see with a sin/cos pot;

Use of 2 x ADC channels (more expensive than logic inputs)

Slightly more complex software for reading/processing the sin/cos outputs.

Advantge; you get an absolute position.



if you want more resolution from a regular grey code rotary encoder. you can use double edge triggering.

So instead of just picking the rising edge on one channel, use both edges, this will give you 48PPQN with a 24PPQN encoder.

I guess, though not tested, you could go a step further and use edge detection on both channels and both edges on both channels giving you 96PPQN from a 24PPQN encoder, though I would expect switch bounce to cause more of a problem at this resolution.

Downside; no absolute position.



Paula












On 2017-07-10 11:31, Julian Schmidt wrote:
I also found them at www.adimpex.it<http://www.adimpex.it/> for 1.15€/pcs. but they have a minimum order amount of 200€ :-/
still looking for a better sample source.
Am 10.07.2017 um 12:09 schrieb Michael Zacherl:

On 9.Jul 2017, at 12:42 , Julian Schmidt <elfenjunge at gmx.net><mailto:elfenjunge at gmx.net> wrote:



Anybody has an idea what the part number for the continuous alpha pots is?

I just asked the other day for an encoder alternative with higher resolution, they would be great!

Maybe I'd have to ask my distributor in taiwan about them.

Thanks for sharing, didn't know such a pot exists.

How would you tell the direction of the movement?



BTW, $15 ... hm ... needs quantities I'd guess ...

https://www.aliexpress.com/item/1pcs-ALPHA-RV112FF-40B3N-22F-0B10K-Encoder-360-degree-turn-gain-potentiometer/32751858615.html



Thanks, Michael.







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