[sdiy] Keyboard Encoder Experiments...

[Amos]

The touch surface on the Moog Voyager almost definitely uses the same
system as the multiple-touch keyboard.  This was also the basis of the
Big Briar Model 331 Touch Plate controller from 1983.


On Feb 13, 2008 5:51 AM, Steve Ridley <spr at spridley.freeserve.co.uk> wrote:
>
> > I have always wanted to have a keyboard where you could actually sense
> > the true position of each key...I don't actually know how useful this
> > might end up being...
>
> Bob Moog did a lot of work on this sort of thing during his "wilderness
> years" in the 1980s.
>
> http://emfinstitute.emf.org/exhibits/moogkeyboard.html
>
> There was an article about it in Computer Music Journal, vol 14 no.2.
>
> http://links.jstor.org/sici?sici=0148-9267(199022)14%3A2%3C52%3AEOTKIT%3E2.0.CO%3B2-8
>
> Each key's top surface had a layer of conductive material with a
> thin insulating layer over it.  An AC signal was applied to each
> corner of the conductive layer, and finger capacitance to ground
> caused a current to flow.  My comparing the currents at each
> corner, finger position on each key could be detected.  Normal
> key movement was detected by capacitive means and there was some
> sort of force sensing resistor arrangement for aftertouch.
>
> Moog did a capacitive pitch bender device for Synton - used in the
> Syrinx and the 3000 keyboard.  Schematics here:
>
> http://www.synthdiy.com/show/?id=906
>
> might give a clue the capacitive sensing in the multiply
> touch sensing keyboard (or might not).
>
> There is mention of an earlier version in the Proceedings Of
> The 1982 Internationa Computer Music Conference, San Fransisco
> CMA, 601-605, but goodness knows where you'll find a copy.
>
>
> There's also some reference to front to back force sensing here:
>
> http://www.bikexprt.com/music/refine.htm
>
> and an early side-to-side motion system in US Patent 1,914,831.
>
>
> Steve
>
>
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