[sdiy] Two parameter mechanical controller thoughts....

[Pete Hartman]

On Sun, Jun 9, 2019 at 6:22 PM <rsdio at audiobanshee.com> wrote:

> Have you ever used a set of digital calipers? They have a pattern that is
> read optically, so the system knows where the slider is positioned at any
> time. 0-calibration is usually necessary on the affordable ones. I believe
> that the pattern is basically the same as the quadrature in a rotary
> encoder, except that it’s straight - not circular. I’m not sure how easy it
> would be to build something like this, but if possible then it would be a
> lot less problematic than something with long rubber bands.
>


Google gets me lots of hits for "linear optical encoder" that involves
transmissive sensors, i.e. it's clear with stripes and you have an LED on
one side and a sensor on the other.

Not having as much luck yet finding anything where both the light source
and the sensor are on the same side, but still digging through various
links.  This really seems like a good way to go, aside from the whole
question of absolute positioning -- when I power on, where is it at?  It
can be saved in non-volatile space but I honestly don't trust that very
far, in terms of long term tracking.
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