[sdiy] Keyboard Encoder Experiments...

[harrybissell at wowway.com]

It seems that you could make the housing, ot the actuator
rod threaded and use a mechanical means to create a null.

Probably you would not want a 'center-off' position so you
might be able to use some diode-deadband similar to what is done
on mod and pitch wheels, where the position voltage need not
be that accurate at null.

Harder (imho) would be to have all the keys (black and white) have
similar feel...

Navy jets are probably a little more 'mission critical' anyway :^)

H^) harry


On Mon, 11 Feb 2008 15:27:07 -0500, mike ruberto wrote
> Jim,
> 
> you may be opening a giant can of worms with the LVDTs. They are used
> as throttle position sensors in certain Navy jet fighters and are 
> very difficult to calibrate. Mostly this is due to the highly temperature
> dependent nature of the device. Often while calibrating these I would
> need to begin the procedure all over again simply because somebody
> walked past the test bench.
> 
> Oh and don't drop them on the floor!
> 
> M. A. Ruberto
> 
> On Feb 11, 2008 2:50 PM, Jim Patchell <patchell at cox.net> wrote:
> > http://www.noniandjim.com/Jim/KeyboardEncoder/KeyboardEncoder.html
> >
> > 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...
> >
> > One app...waterfall keyboard...you can have gates that trigger at a
> > specific position...
> >
> > Aftertouch per key...
> >
> > Etc...
> >
> > The one thing that stopped me was the high cost of position
> > encoders...even cheap ones would have be way too expensive.
> >
> > Then I discovered the LVDT.
> >
> > Commercial ones are also too expensive...but, they are easy to make...
> >
> > The above website shows the DIY one I slapped together last
> > night...seems to work fairly good...better than I expected.
> >
> > Materials : ~$1.00
> >
> > -Jim
> >
> >
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Harry Bissell & Nora Abdullah 4eva