[sdiy] Question how to improve rotary encoder feel

Sat Jun 10 00:53:30 CEST 2017

I've never had a problem with the older Tek 2K, 3K and 4K scopes. Really
liked those, new ones aren't as good.

Had 5 HP/Agilent 33220 signal generators and on all of them the rotary
encoders went bad. It's a common problem with that product line.

But one thing to think about is that they also make encoders that have
numeric values, usually some form of hamming code that can be used for
absolute position.

Jay S.

-----Original Message-----
From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Ben
Bradley
Sent: Friday, June 09, 2017 3:10 PM
To: synth-diy mailing list
Subject: Re: [sdiy] Question how to improve rotary encoder feel

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

On Fri, Jun 9, 2017 at 5:31 PM,  <paula at synth.net> wrote:
> Pete,
>
>  Yes, I love the use of neopixels for the rings, just awesome.
>
> Paula
>
>
>
> On 2017-06-09 23:25, Pete Hartman wrote:
>
> I assume you've seen the Euclidean Circles module?
>
> Pete
>
> On Fri, Jun 9, 2017 at 4:22 PM, <paula at synth.net> wrote:
>>
>> Just remembered these puppies ;
>>
>> http://mayhewlabs.com/products/rotary-encoder-led-ring
>>
>>
>>
>> Shame they're discontinued.
>>
>> Paula
>>
>>
>>
>>
>>
>> On 2017-06-09 15:53, Elain Klopke wrote:
>>
>> I know this is still expensive, but very interesting.... select up to
>> 16-bit resolution...
>>
>>
>>
https://www.digikey.com/product-detail/en/AMT102-V/102-1307-ND/827015?WT.mc_
id=IQ_7595_G_pla827015&wt.srch=1&wt.medium=cpc&WT.srch=1&gclid=CjwKEAjwjunJB
RDzl6iCpoKS4G0SJACJAx-Vl4p0hPzBSpwzSQG49Jod93fHxdtBAS0jDJDcRSuR8RoCIE3w_wcB
>>
>> On Fri, Jun 9, 2017 at 8:21 AM, Tom Farrand <mbedtom at gmail.com> wrote:
>>>
>>> At least some of the encoders on ham equipment are optical encoders.  I
>>> repaired one within the last year.  (The knob has the requisite
fingertip
>>> indentation.)  Being optical in nature, control can be almost anything
you'd
>>> want.  I would guess that the resolution was maybe 120 PPR or better.
The
>>> specific unit was a Yaesu FRG-100 general coverage receiver and the
optical
>>> encoder was the main tuning dial.  If these could be obtained
inexpensively,
>>> they would be wonderful for synth control.  It has been a while since I
>>> looked but think that even these "cheapie" encoders are still in the $30
-
>>> $40 range (or more).
>>>
>>> Tom Farrand
>>>
>>>
>>> On Fri, Jun 9, 2017 at 7:49 AM, Steve <sleepy_dog at gmx.de> wrote:
>>>>
>>>>
>>>> Tom Wiltshire wrote:
>>>> > I did many experiments trying proportional control of a parameter
>>>> > using the velocity of the encoder. It was a disaster, in short.
Mostly much
>>>> > too sensitive, or much too slow. In the end, I finished up with a
system
>>>> > like you suggest, > where you can push the encoder for fine control.
>>>>
>>>> That reminded me of something else with built-in "switching" between
>>>> coarse and fine control:
>>>> Those encoder knobs on many HAM radio transceivers to tune, with a dent
>>>> near the outer radius, where you can rest your fingertip and use the
thing
>>>> as a crank with very quick rotations, or grab the whole thing for fine
>>>> control.
>>>> Needs more space of course, for those things are bigger than the
average
>>>> knob on a synth module. And the encoder has more wear if the solution
is
>>>> "turn it more!", if it's a mechanical one. And I'd guess things finger
tip
>>>> cranking doesn't feel nice with some encoders hard detent.
>>>> Something like this:
>>>>
>>>>
https://www.adafruit.com/product/2055https://www.adafruit.com/product/2055
>>>>
>>>>
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>>>
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