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Capacitance-based moisture sensor and controller

  • US 20060144437A1
  • Filed: 12/29/2004
  • Published: 07/06/2006
  • Est. Priority Date: 12/29/2004
  • Status: Abandoned Application
First Claim
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1. A moisture sensor device comprising:

  • a probe forming a capacitor and adapted to be positioned within soil;

    a controller coupled to the probe, the controller comprising;

    a variable frequency oscillator, the frequency of the variable frequency oscillator varies as a function of a capacitance of the probe, the capacitance varies as a function of a moisture content of the soil;

    a reference oscillator; and

    a circuit for comparing the frequency of the variable frequency oscillator to a frequency of the reference oscillator; and

    a switch coupled to the circuit and adapted to be coupled to a power output line of an irrigation controller and a power actuation line coupled to a valve.

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