Dont forget the vast amounts of static these machines generate.

I used to run a paper converting machine many many years ago and the sparks 
from the static generated by the paper unrolling, cutting and re-rolling was 
enough to jump 3 or 4 inches.

I still have nightmares to this day about walking up to the machine and 
getting zapped by a couple of hundred thousand volts lol.

Dom
----- Original Message ----- 
From: "Russell McMahon" <apptech@paradise.net.nz>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Tuesday, September 26, 2006 4:57 PM
Subject: Re: [EE]: High Speed Thickness Measurement


>> How would you do this? I can imagine using the sheet as the
>> dielectric
>> between 2 plates. Would a tiny change in thickness create enough
>> variance of
>> capacitance to measure accurately?
>
> If you can maintain a sensor at a small distance above the paper as it
> eg travels over a roller then the change in capacitance should be
> highly proportional to paper thickness. Dielectric constant of paper
> relative to air (1) governs how large a swing you'll get.
>
>
>
>        Russell
>
>
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