Re: Soil moisture sensors

["Robert L. Bass" <robertlbass@xxxxxxxxxxx>]

> I'm trying to use a Watermark soil moisture sensor in the my home
> automation
> project. I believe this sensor cannot be read as a standard resistive
> sensor
> using a DC voltage across the sensor, the voltage across the sensor must
> be
> A/C.

The Watermark sensor varies resistance inversely with soil moisture content.
It should work fine with a DC analog sensing circuit.

> Also, Irrometer who make the sensor don't seem to want to giveout details
> of
> the sensor's response curve, and temperature correction details.
> So,
>
> Does anyone have, or know where i can get an interface circuit schematic
> diagram for the Watermark sensor.
>
> Does anyone have, or know where i can get details of the response curve,
> and
> temperature compensation details.

There's a UC website which includes a downloadable spreadsheet you can use
to graph sensor readings.  The URL follows:
http://alfalfa.ucdavis.edu

Enjoy.

--

Regards,
Robert L Bass

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