Tuesday, March 31, 2020

UI/front panel design - living post

Here I'll post stuff about the UI that comes up during my research.

Endless potentiometers:


Also known as 360 degree pots - carbon potentiometers without an end stop. Alpha has one that has two carbon paths, making it possible to sense position and direction, and the paths have no jump in resistance at the end but rather increase then decrease. Can be used if we want more steps than an encoder can offer.

Lifetime for both pots and encoders from Alpha is 15000 turns.

One example is Alpha RV112FF

https://hackaday.io/project/171841-driveralgorithm-for-360-deg-endless-potentiometer
https://forum.arduino.cc/index.php?topic=531613.0


IDEA: For filter, use a "finger dial" like the data wheel on the Native Instruments KORE 2, with an option to do a fine grained sweep by pressing "shift" (this could really be an option for all pots, with a common shift somewhere).

Encoders: 



24 pulse/24 detent https://www.reichelt.com/de/en/alps-stec12e-rotary-pulse-encoder-24-24-vert-w-pb-stec12e08-p73923.html

Alternatives (like without detents):
https://tech.alpsalpine.com/prod/e/html/encoder/incremental/ec12e/ec12e_list.html

Each detent may give up to 4 increments when using a non-detent encoder. More info on this and on how to read multiple encoders using interrupts (and port expanders) here:

http://makeatronics.blogspot.com/2013/02/efficiently-reading-quadrature-with.html

https://www.eevblog.com/forum/beginners/rotary-encoder-pulses-and-detents-and-interrupts-vs-polling/

https://arduino.stackexchange.com/questions/52909/reading-several-rotary-encoders


LED ring:


Must decide if all or only one led is lit. Measure current used.

Can use a 7-segment display chip like the MAX7221


Light pipe solutions:
Laser cut a black ring with holes the size of the led. Put a diffused (engraved acrylic or milky white acrylic) and colored acrylic on top - will give clearly separated leds.

CNC a ring with holes, but slant the edges so they meet at the surface, will give minimum separation. May be a problem that viewing angle of the led does not spread the light enough.

Experiment with diffuser at top/bottom for increased spread

3D-print similar ring with slanted edges? Laser cut the bottom hole?

Make light pipes with separation, laser cut as a profile and mounted upright, will make it possible to have slanted edges in one dimmension,. with good internal reflection (?)

My initial tests of light pipes: https://atosynth.blogspot.com/2020/04/led-dial-light-pipes.html

A cool project with RGB ledring: https://muffwiggler.com/forum/viewtopic.php?t=217920

Knobs

White moog/boss style knobs:
https://lovemyswitches.com/knobs/?utm_source=share&utm_medium=ios_app
https://lovemyswitches.com/colored-boss-style-knob-knurled-shaft-11-x-20mm/
https://lovemyswitches.com/colored-boss-style-knob-1-4-smooth-shaft-11-x-20mm/
https://lovemyswitches.com/1360-tall-boy-knob-12-x-16mm/
Also has lots of other sizes but not white

Cheaper kn-13560 knobs: https://www.aliexpress.com/item/32430188458.html

https://www.conrad.com/p/alps-dk13-164a645-rotary-knob-for-encoder-with-plastic-shaft-rotary-button-700619

Switches

--> 6450 Marquardt
Cherry MX Low Profile

Other ideas:


Make the front panel detachable and use an RJ-45 to connect it to the synth, making it desktop friendly.

Morph functionality. Set A, set B (either patch or variation of patch). Big dial for morphing. Envelope based morph.

CNC'd mod wheels with acrylic inside?

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