On Tue, 16 Sep 2003, Russell McMahon wrote:

> This page describes SDC's (Symmetric Differential Capacitor) Sensors.
> These are a relatively recent development of the traditional use of
> capacitance to measure position changes.
> SDC sensors are stunningly intuitive (once you get the idea :-) ) and offer
> potentially very high resolution and accuracy at relatively low cost.
>
> SDC lends itself to amateur and low cost implementations (unlike some
> methods which are applicable only to advanced or high technology users.) A
> basic measurement system could be produced from scrap material and off the
> shelf parts for a few dollars.
>
>         http://physics.mercer.edu/petepag/sens.htm

FWIW, I know of prior art that most certainly nullifies the patent upon
which their technology is based... SRI was working on this stuff in the
early 90's.

Scott

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