Csaba, measuring wood moisture is not a simple problem.
Depends if you need to measure volume or surface. It's different things,
because the moisture and the resistivity on long wood fiber or
perpendicular to wood fibre will gave you major different results.
Also, you can't do it right in DC because of electrolysis effect.
A simple approach is to study the input stage of a conductometer. You need
something like this and you may find schematics of Radelkis
conductometers in Hungary.
You need to built a kHz range curent generator and to measure potential
between two ( or four ) electrodes with an electrometer ( very high
impedance volmeter ) Usual range is 10 Mohm to 1000 Mohm and depends also
on wood type, but as I remember the interesting range is 50Mohm to 300
Mohm.

Succes, Vasile


On Thu, 6 Sep 2001, Also-Antal Csaba wrote:

> Hi guys
>
> I have a problem. I would like to measure resistance in Gohm-Mohm range.
> Big accuracy is not necessary because this will be used in a wood-drier.
> How can I start?
>
> udv
> Csaba
>
> --
> http://www.piclist.com hint: The PICList is archived three different
> ways.  See http://www.piclist.com/#archives for details.
>
>

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.