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Anyone know of cheap ground moisture meters ??? — Parallax Forums

Anyone know of cheap ground moisture meters ???

ArchiverArchiver Posts: 46,084
edited 2001-05-30 11:42 in General Discussion
Hi All!

I am wanting to investgate the ability to measure the ground moisture
content in my garden remotely [noparse]:)[/noparse] ... ideally I can have a moisture sensor /
BS2 / RF unit / Solar panel that will send the data to the PC in the house.

The part I am unsure of is the moisture meter ... I want to bury them in the
ground all around my garden (maybe 20-30 of them) and then make a central
A/D - controller that will read them.

Does anyone have any good pointers to any cheap and dirty moisture meters
(if they are very expensive I will never get it past the budget committee
(wife))..... any links will help though even to expensive meters ....

Thanks!
John Ledford

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2001-05-30 01:57
    Gypsum blocks with leads embedded are used for this purpose. They vary inresistance with moisture. They are cheap, but I'm not sure where you get them. Call local University Ag research irrigation specialist?


    At 06:31 PM 5/29/01 -0500, you wrote:
    >Hi All!
    >

    >I am wanting to investgate the ability to measure the ground moisture
    >content in my garden remotely [noparse]:)[/noparse] ... ideally I can have a moisture sensor /
    >BS2 / RF unit / Solar panel that will send the data to the PC in the house.
    >

    >The part I am unsure of is the moisture meter ... I want to bury them in the
    >ground all around my garden (maybe 20-30 of them) and then make a central
    >A/D - controller that will read them.
    >

    >Does anyone have any good pointers to any cheap and dirty moisture meters
    >(if they are very expensive I will never get it past the budget committee
    >(wife))..... any links will help though even to expensive meters ....
    >

    >Thanks!
    >John Ledford
    >

    >

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    >

    >

    >

    >



    Roger Edberg
    roger@industrialartist.com
    http://www.industrialartist.com
    also:
    Technical Tree Service
  • ArchiverArchiver Posts: 46,084
    edited 2001-05-30 03:13
    I would suggest using an astable 555 oscillator with the gypsum probe
    being the RC resistance element. Having AC instead of DC across the
    moist metal probes will reduce corrosion.


    At 5:57 PM -0700 5/29/01, Roger Edberg, you wrote about Re:
    [noparse][[/noparse]basicstamps] Anyone know of cheap ground moisture:


    >Gypsum blocks with leads embedded are used for this purpose. They
    >vary inresistance with moisture. They are cheap, but I'm not sure
    >where you get them. Call local University Ag research irrigation
    >specialist?
    >
    >
    >At 06:31 PM 5/29/01 -0500, you wrote:
    > >Hi All!
    > >
    > >I am wanting to investgate the ability to measure the ground moisture

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    Chuck Britton Education is what is left when
    britton@n... you have forgotten everything
    North Carolina School of Science & Math you learned in school.
    (919) 286-3366 x224 Albert Einstein, 1936
  • ArchiverArchiver Posts: 46,084
    edited 2001-05-30 07:00
    >Hi All!
    >
    >I am wanting to investgate the ability to measure the ground moisture
    >content in my garden remotely [noparse]:)[/noparse] ... ideally I can have a moisture sensor /
    >BS2 / RF unit / Solar panel that will send the data to the PC in the house.
    >
    >The part I am unsure of is the moisture meter ... I want to bury them in the
    >ground all around my garden (maybe 20-30 of them) and then make a central
    >A/D - controller that will read them.
    >
    >Does anyone have any good pointers to any cheap and dirty moisture meters
    >(if they are very expensive I will never get it past the budget committee
    >(wife))..... any links will help though even to expensive meters ....
    >
    >Thanks!
    >John Ledford

    Hi John,

    Here are a couple of links for soil moisture measurement and science:
    http://www.sowacs.com/ ' sources, theory, wow
    http://www.pedosphere.com/contents.cfm ' extensive tutorials

    Here is a '555 circuit for AC isolated conductance measurements
    http://www.emesystems.com/OWL2face.htm#conductivity
    This is similar to the circuit in unit 5 of Earth Measurements.
    http://www.emesystems.com/EarthM/em5.pdf
    Gypsum blocks can be molded in a plastic film can around stainless
    steel screws held in the lid.

    Tensiometers are the way to go if you want to soften up the budget
    committee for the cheaper stuff...
    http://www.emesystems.com/OWL2face.htm#Irrometer

    -- regards,
    Thomas Tracy Allen Ph.D.
    electronically monitored ecosystems
    mailto:tracy@e...
    http://www.emesystems.com
  • ArchiverArchiver Posts: 46,084
    edited 2001-05-30 11:42
    About 10 years ago, we made sensors out of a couple of pieces of cooper rod
    about 1/8 in. diameter, and put them in pairs through a standard pipe
    fitting with some epoxy to hold them in. Either threading or flattening the
    top of each rod made it possible to connect them. A simple comparator
    circuit with a low-current DC supply (almost any voltage will work - but I
    seem to remember using 12V) gave good results. We put 12V on one rod, and
    measured the level on the other rod, which was about 1/8 inch away. The
    trick was determining at which point you wanted to be told the soil was dry.
    They were pretty reliable and consistent (and inexpensive).

    Chris

    >
    Original Message
    > From: John Ledford [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=oalG3v39-efstoEHTnGLDYX8N5fVJ7uK-jMXJjbVBmsKVVHMWNQ0f-UUB4CUJzps2Pg4MSBRFviSok-1R9cx]john@k...[/url
    > Sent: Tuesday, May 29, 2001 7:32 PM
    > To: Basic stamps
    > Subject: [noparse][[/noparse]basicstamps] Anyone know of cheap ground moisture
    > meters ???
    >
    >
    > Hi All!
    >
    > I am wanting to investgate the ability to measure the ground moisture
    > content in my garden remotely [noparse]:)[/noparse] ... ideally I can have a
    > moisture sensor /
    > BS2 / RF unit / Solar panel that will send the data to the
    > PC in the house.
    >
    > The part I am unsure of is the moisture meter ... I want to
    > bury them in the
    > ground all around my garden (maybe 20-30 of them) and then
    > make a central
    > A/D - controller that will read them.
    >
    > Does anyone have any good pointers to any cheap and dirty
    > moisture meters
    > (if they are very expensive I will never get it past the
    > budget committee
    > (wife))..... any links will help though even to expensive meters ....
    >
    > Thanks!
    > John Ledford
    >
    >
    > To UNSUBSCRIBE, just send mail to:
    > basicstamps-unsubscribe@yahoogroups.com
    > from the same email address that you subscribed with. Text
    > in the Subject and Body of the message will be ignored.
    >
    >
    > Your use of Yahoo! Groups is subject to
    > http://docs.yahoo.com/info/terms/
    >
    >
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