[sdiy] Ensoniq patent, was: distance meter for keyboard, was: Where to get special white keys?

[cheater cheater]

Amos,
I am slightly partial against using force for poly AT. It makes it
somewhat difficult to use. I think an additional distance of the key;s
throw which requires a bit more pressure (so that you can notice when
you starts) but still allows the key to actually travel would be much
better. This is why I'm mostly looking for a distance meter rather
than a pressure sensor.

I'm actually not sure of any classical instruments that use the key
*displacement* to add a level of expression. Do you guys know any?

Cheers
D.

On Mon, Mar 2, 2009 at 6:05 PM, Amos <controlvoltage at gmail.com> wrote:
> google "Quantum-Tunneling Composite"...
> a rather novel force-to-voltage transducing polymer.  Neat stuff by the
> looks, but I haven't played with it myself yet.
> http://www.cui.com/srchresults.asp?catky=560054&subcatky=227398
>
> Need to get some in soon... could be all sorts of nifty haptic interfaces
> via this stuff.
>
> -Amos
>
> On Mon, Mar 2, 2009 at 12:41 PM, cheater cheater <cheater00 at gmail.com>
> wrote:
>>
>> What is QTC, Amos?
>>
>> Also, as far as shutter schemes are concerned: those can skip. This
>> would be very detrimental to the key's performance, as it would
>> pretend the key is depressed less than it really is. This means that
>> the key actually being fully depressed would never register.
>> Intermittent fault.
>>
>> D.
>>
>> On Mon, Mar 2, 2009 at 5:39 PM, Amos <controlvoltage at gmail.com> wrote:
>> > there's the option of an infrared emitter and phototransistor pair, with
>> > a
>> > moving vane or shutter between them & attached to the key.  Something
>> > like
>> > this ought to be reasonably fog-resistant I would expect, and if it's
>> > hidden
>> > beneath the keybed should be resistant to ambient/sunlight issues.  I
>> > don't
>> > know if there are any typical temperature-related changes to linearity
>> > or
>> > operating point with IR phototransistors, but none of the circuits I've
>> > seen
>> > which use these devices seem to have any temperature compensation so I
>> > suspect it's not a significant factor.
>> >
>> > Somebody (or multiple persons) on this list was/were working on a
>> > QTC-based
>> > poly-AT scheme last year or so...
>> > any progress on that front?
>> >
>> > Cheers,
>> >
>> > Amos
>> >
>> > On Mon, Mar 2, 2009 at 11:53 AM, cheater cheater <cheater00 at gmail.com>
>> > wrote:
>> >>
>> >> You don't really need an additional contact.
>> >> Just tell the user not to touch the keyboard when calibrating... like
>> >> the SQ-80 does!
>> >> DON'T TOUCH KEYBOARD << SQ80 does it like this. I love it.
>> >> but it could be useful, indeed.
>> >> now the question is whether temperature can change the *linearity*.
>> >> That's more important, I think. That's also a reason why I had
>> >> thoughts about an optical sensor.
>> >> Optical mice use cheap optical sensors... you can have a mouse like
>> >> that for 5 dollars, can't you? And that's including all the other crap
>> >> they put in em :) You'd also need a focused laser beam... no idea how
>> >> much those could be.
>> >>
>> >> Optical sensors don't work that well in smoky rooms though... so no
>> >> jarre fog i guess? This definitely disqualifies optical technology for
>> >> some people ;)
>> >>
>> >> On Mon, Mar 2, 2009 at 2:42 PM, ChristianH <chris at chrismusic.de> wrote:
>> >> > On Mon, 02 Mar 2009 07:31:06 -0700 Ian Fritz <ijfritz at comcast.net>
>> >> > wrote:
>> >> >
>> >> >> At 11:52 PM 3/1/2009, Simon Brouwer wrote:
>> >> >>
>> >> >> >Have you looked at the spec sheet on that page? Although not
>> >> >> > particularly
>> >> >> >linear, these appear to be analog sensors.
>> >> >>
>> >> >> Ooops!  Right you are.  I got confused by the Futurlec description.
>> >> >>  These
>> >> >> might be worth looking into further.  One thing to be careful about
>> >> >> is
>> >> >> whether they have temperature compensation.
>> >> >>
>> >> >> Ian
>> >> >
>> >> >
>> >> > I don't know about temperature characteristics in this case, but a
>> >> > simple offset could be compensated by measuring the all-notes-off
>> >> > values.
>> >> >
>> >> > If there *is* an additional key contact, that is.
>> >> >
>> >> > Christian
>> >> >
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