Soil moisture control system and method
First Claim
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1. A soil moisture control system comprising:
- an alternating current source for supplying alternating current;
a switch and a magnetic coil serially connected to said alternating current source, said magnetic coil being for connection to an irrigation water valve so as to control the opening and closing of the water valve;
a soil moisture sensor having first and second spaced electrically conductive graphite rods forming probes for sensing the moisture in soil between said probes, first and second resilient metal springs wrapped around the cut into said first and second graphite rod probes, respectively, said first and second metal springs being connected to said alternating current source so that alternating current passes between said probes when said sensor is immersed in moist soil, said sensor being connected to control said switch; and
including a gate circuit connected to said switch for controlling said switch and said soil moisture sensor being connected to said gate circuit so that said switch changes states when said sensor detects a predetermined amount of moisture in the soil between said probes so that said soil moisture control system inhibits delivery of irrigation water to the soil when soil moisture is adequate.
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Abstract
Soil moisture control system senses subsoil moisture by AC conductivity and turns on irrigation valve when the sensor indicates the need for additional moisture. An adjustment is connected to the sensor to adjust the level at which adequate soil moisture is signaled.
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Citations
12 Claims
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1. A soil moisture control system comprising:
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an alternating current source for supplying alternating current; a switch and a magnetic coil serially connected to said alternating current source, said magnetic coil being for connection to an irrigation water valve so as to control the opening and closing of the water valve; a soil moisture sensor having first and second spaced electrically conductive graphite rods forming probes for sensing the moisture in soil between said probes, first and second resilient metal springs wrapped around the cut into said first and second graphite rod probes, respectively, said first and second metal springs being connected to said alternating current source so that alternating current passes between said probes when said sensor is immersed in moist soil, said sensor being connected to control said switch; and including a gate circuit connected to said switch for controlling said switch and said soil moisture sensor being connected to said gate circuit so that said switch changes states when said sensor detects a predetermined amount of moisture in the soil between said probes so that said soil moisture control system inhibits delivery of irrigation water to the soil when soil moisture is adequate. - View Dependent Claims (2, 3, 4)
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5. A soil moisture control system comprising:
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an alternating current source for supplying alternating current; a switch and a magnetic relay coil connected to actuate relay contacts which control the flow of power to the solenoid of a water control valve so as to control the opening and closing of said water valve; a soil moisture sensor having first and second spaced electrically conductive graphite rods forming probes for sensing the moisture in soil between said probes, first and second resilient metal springs wrapped around and cut into said first and second graphite rods probes, respectively, said first and second metal springs being connected to said alternating current source so that alternating current passes between said probes when said sensor is immersed in moist soil, said sensor being connected to control said switch; and a gate circuit connected to said switch for controlling said switch, said gate circuit comprising a triac having one of its main terminals connected through a variable resistor to said first probe and having its gate connected to said second probe and having its main terminals connected to actuate said switch so that said switch changes states when said sensor detects a predetermined amount of moisture in the soil between said probes so that said soil moisture control system inhibits delivery of irrigation water to the soil when soil moisture is adequate. - View Dependent Claims (6, 7, 8, 9)
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10. The method of control of irrigation water comprising the steps of:
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preparing a ground moisture sensor having first and second spaced carbon rod probes and making electrical contact with the carbon rod probes by wrapping a separate metallic spring around each of the probes so as to cut into the carbon rod probes; inserting sensor having the first and second spaced probes into soil in which moisture is to be sensed; applying alternating current across said spaced carbon probes through the contact springs; measuring current so that when the current between the probes changes across a critical value a signal is emitted; and controlling a sprinkler valve in response to the emitted signal. - View Dependent Claims (11, 12)
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Specification