Looking for a Soil Moisture Sensor (for Picaxe 18X datalogge

[Barry Cugley]

Hello

I have just built the datalogger Picaxe 18X datalogger (kit number AXE110).
It seems to be working as it should with the temperature and light sensors
that came with the kit.

Now I want to add a soil moisture sensor to the datalogger. The purpose of
the setup will be to determine if a patch of garden needs to be watered, so
accurate measurement of the soil moisture content should not be necessary. A
sensor which could tell the difference between "damp", "wet" and "dry" soil
would probably do fine. Even a sensor which could tell the difference
between "wet" and "dry" would be a start.

Does anyone know what can be used as a soil moisture meter with this kit?

Thanks for any assistance
Barry

 

[The Real Andy]

On Fri, 18 Jun 2004 16:43:00 +0800, "Barry Cugley"
<barryc@cygnus.uwa.edu.au> wrote:

Hello

I have just built the datalogger Picaxe 18X datalogger (kit number AXE110).
It seems to be working as it should with the temperature and light sensors
that came with the kit.

Now I want to add a soil moisture sensor to the datalogger. The purpose of
the setup will be to determine if a patch of garden needs to be watered, so
accurate measurement of the soil moisture content should not be necessary. A
sensor which could tell the difference between "damp", "wet" and "dry" soil
would probably do fine. Even a sensor which could tell the difference
between "wet" and "dry" would be a start.

Does anyone know what can be used as a soil moisture meter with this kit?

Thanks for any assistance
Barry

Two probes stuck in the ground. I recall seeing something like this in
jaycar or dse perhaps.

If you want to know the amount of water, your cheapest bet will be a
gypsum soil moisture sensor. You are going to want to build it
yourself, cause to buy one isn't going to be cheap.

Try google for more answers

 

[Mark Little]

"Barry Cugley" <barryc@cygnus.uwa.edu.au> wrote in message
news:cau9t5$ffp$1@enyo.uwa.edu.au...

Hello

I have just built the datalogger Picaxe 18X datalogger (kit number
AXE110).
It seems to be working as it should with the temperature and light sensors
that came with the kit.

Now I want to add a soil moisture sensor to the datalogger. The purpose of
the setup will be to determine if a patch of garden needs to be watered,
so
accurate measurement of the soil moisture content should not be necessary.
A
sensor which could tell the difference between "damp", "wet" and "dry"
soil
would probably do fine. Even a sensor which could tell the difference
between "wet" and "dry" would be a start.

Soil moisture can be measured in a relative sense with just two probes.
However, you should use AC to energise the probes as using DC will
eventually cause problems by electrolysis. You can use an astable
multivibrator using, say, a 555 look-alike or a couple of I/O pins on the
PIC if they are available and you want to do some programming.

Mark