[sdiy] Two parameter mechanical controller thoughts....

[Pete Hartman]

I've been kind of stuck on pulleys having their axes perpendicular to the
panel/pcb surface, but if they are parallel....  Ok.  That can replace the
soft pot without taking up a lot of space, and makes some aspects of this
simpler.  Still need a rail; those linear bearings at McMaster are spendy,
but I haven't looked to see if there are less quality solutions that are
"good enough" from elsewhere.  The idea of having 4 x 100mm controls on a
module is a minimum $160 just for the hardware, not counting encoders,
pulleys, etc. is kind of daunting for a DIY project.

Pete


On Fri, Jun 7, 2019 at 12:57 PM thresholdpeople <
thresholdpeople at protonmail.com> wrote:

> The Appendage is great.
>
> It's kind of a trade off in that the softpot takes up less space for sure,
> but then it needs all this other sort of support infrastructure to make the
> encoder right. Using a belt and pulley system would inherently provide the
> infrastructure, but it's bigger on the inside.
>
> Watching the Collidoscope video the lever riding on the softpot looks kind
> of wobbly. Using a mechanism of some sort like a linear bearing or belt and
> pulley etc would create a much more robust hands on instrument.
>
> Another thought is that the mechanism is similar to the Ondes Martenot
> ring. Perhaps if approached from that perspective you can have something
> that's less obviously an encoder/knob on the top, and something
> built/disguised more into the slider mechanism.
>
>
>
>
>
> ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
> On Friday, June 7, 2019 1:39 PM, Pete Hartman <pete.hartman at gmail.com>
> wrote:
>
> The Collidoscope itself is actually a lot simpler on the inside that it
> would appear from the videos.
>
> It uses a Teensy to convert the encoder output and softpot position (and
> any other sensors) to midi messages.
>
> It has MIDI from the keyboard and the Teensy going to a raspberry pi that
> displays the waveform on a large monitor.
>
> It uses a FocusRite interface to handle audio in and out duties for the Pi.
>
> The display monitor is mounted under the surface of the "table" with a
> divider down the middle.  The Pi does all the synthesis and display work.
>
> I was kind of liking the softpot idea, because I have one already set up
> as the controller for an Appendage (check electro-music.com for some of
> the details about the Appendage, it's a very feature-rich ribbon
> controller).
>
> One advantage it has is that the belt/pulley idea requires that you have
> additional space to the side of the carriage for mounting the belt/pulley
> behind the panel.  The softpot, if mounted appropriately doesn't have to
> add more than ~8mm to the width of the overall mechanism, and depending on
> the details, could conceivably add zero.  I'd expect mounting an encoder
> and belt and pulleys for the belt to take up more than that.
>
> Pete
>
>
>
>
> On Fri, Jun 7, 2019 at 12:27 PM Ben Bradley <ben.pi.bradley at gmail.com>
> wrote:
>
>> I remember the "Crazy Synthesizer Demo" from a few years ago, and just
>> looked at it again. From what I remembered, I thought it was just a
>> big touch-screen like an ipad, but I see it's a long slider with a
>> round knob.
>>
>> There's also the ribbon controller like on the Micromoog, and I recall
>> seeing one that's substantially longer. That's not what you want, but
>> it's another idea.
>>
>> I kind of like the belt/pulley idea. This could go to a
>> high-resolution rotary encoder, microcontroller and a high-resolution
>> DAC to generate a precise control voltage that feels "analog."
>>
>> On Fri, Jun 7, 2019 at 1:13 PM Quincas Moreira <quincas at gmail.com> wrote:
>> >
>> > I think I'd lose the softpot too, and use some kind of belt/pulley to
>> turn a rotary pot/encoder
>> >
>> > On Fri, Jun 7, 2019 at 9:58 AM thresholdpeople via Synth-diy <
>> synth-diy at synth-diy.org> wrote:
>> >>
>> >> The thing with CNC gantry systems like 3D printers is that most lower
>> end ones use stepper motors for both the drive and positioning, so running
>> them in reverse won't be possible to create a control voltage based on
>> position with out a whole lot of extra circuitry. However they may often
>> have parts like linear bearings, precision-ish shafts, and all sorts of
>> other hardware that could be re-purposed.
>> >>
>> >>
>> >>
>> >> Check out Author & Punisher - http://www.tristanshone.com/ - he makes
>> awesome controllers, and has one or two that are as you're describing,
>> Pete. He's pretty open about construction and functionality.
>> >>
>> >> ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
>> >> On Friday, June 7, 2019 9:55 AM, Pete Hartman <pete.hartman at gmail.com>
>> wrote:
>> >>
>> >>
>> >>
>> >> On Fri, Jun 7, 2019 at 7:07 AM bbob <fluxmonk at gmail.com> wrote:
>> >>>
>> >>> i'd go wireless - bluetooth or ble from whatever controls are on the
>> carriage, and a time-of-flight sensor to measure the carriage position.
>> there's probably a lot of hardware bits you could repurpose from folks
>> developing diy 3d printers for the carriage mechanics.
>> >>>>
>> >>>>
>> >>
>> >> I'm not sure wireless would be practical for within-the-module
>> communications in a Euro module or standalone controller meant to interface
>> with Euro.....
>> >>
>> >> 3D printer carriages would be a good source of inspiration though.
>> >>
>> >> The linear bearings at McMaster look really interesting, I'll have to
>> spend some time digging around in that stuff.
>> >>
>> >> Thanks
>> >>
>> >> Pete
>> >>
>> >>
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>> >
>> >
>> > --
>> > Quincas Moreira
>> > Synth Diy Guy
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