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Moisture/Humidity Detector question

Discussion in 'General Electronics' started by SS, Sep 17, 2003.

  1. SS

    SS Guest


    I need to switch on sprinkler system based on moisture, can some one please
    tell which is a good sensor and where to get them from - also they should
    not be very expensive.


  2. Mark Jones

    Mark Jones Guest

    If you're watering something like a lawn, then you'd want a sensor that
    measures the soil moisture. Measuring air humidity vs. soil moisture is two
    totally different things. Most soil-moisture monitoring devices employ a
    simple process of passing a tiny electrical current through two electrodes
    stuck into the ground. When the soil is wet, electricty can flow through the
    soil much easier than when it is dry. If a sensitive meter is connected to
    these probes, then it will "read out" the conductivity, and hence the level
    of moisture content.... sounds like a rewarding project.

    Also keep in mind, it's best to water at night, when there is less wind,
    more humidity, and no sun to burn off all that precious water. Of course
    then you must implement a way to avoid over-watering... I've actually seen
    mold growing on grass because of that. But anyways, do a google search
    ( for "conductivity tester schematic" or "soil monitor
    schematic," etcetera and you'll soon find mounds of similar projects.

  3. Tim Williams

    Tim Williams Guest

    On the shadowed (north) side of our house, you can take a walk through
    it and churn up a bunch of fine white dust. Yup, mildew...

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