Keyboard Encoder

[patchell]

    Something to consider.  I suspect it would be a wash though, cost wise.
Ferrite rods are not cheap either.  The one I purchased today cost me a couple
of bucks.  It might be worth it from a mechanical point of view though.

Dave Halliday wrote:

> How about using a linear hall effect encoder - more $$$ up front but a lot
> less time involved in making them.
>
> Got the idea from:
> http://www.seanet.com/~tpaddock/mag2cv.html
>
> Here is the manufacturers page:
> http://www.allegromicro.com/selguide/hed1.htm
>
> they are listed as costing from $1.50 to about $3.00 depending on linearity,
> temperature range and sensitivity.  They are generous with samples - when I
> requested some, I get a bag of six units plus lots of data sheets.
>
> As I said, there would be more $$$ up front but a significant drop in
> construction hassles and time.
>
> Dave
>
> -----Original Message-----
> From: patchell [mailto:patchell at silcom.com]
> Sent: Monday, October 02, 2000 3:08 PM
> To: synth-diy at node12b53.a2000.nl
> Subject: Keyboard Encoder
>
>     I am working on a keyboard encoder I had an idea for a long time
> ago, but never tried. (this will go into the Paia 8700 keyboard I am
> rebuilding).
>
>     It consists of a 5/16 in OD styrene tube, about 1.5 inches long.
> The I.D. is 1/4".  On this tube, I wrapped two coils, about .75" long on
> each have of the tube.  Inside the tube, I run a 1/4" Dia ferrite rod
> that can move back and forth.
>
>     I apply a fairly high frequency signal to one coil, and look at the
> output from the other coil.  As you move the ferrite rod into the tube,
> the signal on the output increases as some function of the position.
> (Not exactly linear, but that is not really important, I think).
>
>     Anyway, now that the idea at least shows promise, I will have to see
> what I can do to make it come to life.  There are a few mechanical
> problems that need to be solved (I am not much of a mechanical
> engineer).  Plus, I am not sure exactly how to apply this to a keyboard,
> but, I am sure I will come up with something.
>
>     **This was the perversion of the 8700 I was refering to in a
> previous post.**
>
> --
>  -Jim
> ------------------------------------------------
> * Visit:http://www.silcom.com/~patchell/
> *-----------------------------------------------
> *If you didn't buy a home in Santa Barbara,
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--
 -Jim
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* Visit:http://www.silcom.com/~patchell/
*-----------------------------------------------
*If you didn't buy a home in Santa Barbara,
* You didn't pay enough!
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