Re: Soil Humidity Sensors

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Article #10952

#10952

From: Juerg Stettbacher
Date: Thu, 01 Oct 1992 10:16

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Gabriel Gonzalez (ggonzale@mtecv2.mty.itesm.mx) wrote:
: Hello there!
: 
: I'm working in an automatic watering system for this campus, and I need
: to know how can I measure the humidity level of the soil. I need to get
: an electrical signal representing this parameter. I've searched in
: catalogs (like Omegas's) and found nothing. I've thought about measuring
: the earths resistance, but found no easy way of doing it. It doesn't
: have to be a very accurate measurement, but I need a good (read it
: stable) signal to work with.


Hi Gabriel

Measuring the earths resistance would be the easyest and cheapest way
to estimate the humidity. You will get higher accuracy using a current
source but also just a FET with some temperature compensation (stick
the gate and a constant voltage pin into the ground, separated by
about 10 cm) will give you a 'good` signal.
But remember: resistance is not humidity!

juerg at ethz switzerland

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Path: arc1-ca.pugleaf.net!sparky!uunet!news.univie.ac.at!chx400!bernina!isibee7!stettbac
From: stettbac@isibee7 (Juerg Stettbacher)
Subject: Re: Soil Humidity Sensors
Message-ID: <1992Oct1.101617.6801@bernina.ethz.ch>
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Date: Thu, 1 Oct 1992 10:16:17 GMT
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