Automatic control of the moisture content of the soil
First Claim
1. A moisture sensing control for a valve in a conduit by which the soil in an area is watered, said control including a pair of contacts to be inserted in the soil, first and second circuits, and input leads, one lead including a voltage divider, said voltage divider comprising a resistor string and a capacitor, leads of substantial length connecting said contacts to said one input lead across the capacitor, said string including first and second adjustable resistors, the first establishing a dry threshold and providing an input for the first circuit and the second establishing a wet threshold and an input for the second circuit, each circuit including a Schmitt trigger and means operable in response to the threshold that circuit monitors to deliver shaped pulses to the associated trigger, and a third circuit including means operable to effect the opening and closing of said valve and means connected to each trigger to respond to the output thereof, that of the first circuit trigger to effect valve opening and that of the second circuit trigger to effect valve closing.
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Accused Products
Abstract
The moisture content of the soil in each of a number of areas is maintained between predetermined wet and dry thresholds by a control having circuits operative in response to detected thresholds through contacts inserted in the soil to effect the opening and closing of a valve in the conduit by which water is delivered to that area. Typically a number of conduits are connected directly or through junctions to a common water supply and where that supply is pump controlled, the control for each conduit includes circuitry that enables a switch in the pump motor circuit to be closed whenever the valve operated by that control is open.
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Citations
19 Claims
- 1. A moisture sensing control for a valve in a conduit by which the soil in an area is watered, said control including a pair of contacts to be inserted in the soil, first and second circuits, and input leads, one lead including a voltage divider, said voltage divider comprising a resistor string and a capacitor, leads of substantial length connecting said contacts to said one input lead across the capacitor, said string including first and second adjustable resistors, the first establishing a dry threshold and providing an input for the first circuit and the second establishing a wet threshold and an input for the second circuit, each circuit including a Schmitt trigger and means operable in response to the threshold that circuit monitors to deliver shaped pulses to the associated trigger, and a third circuit including means operable to effect the opening and closing of said valve and means connected to each trigger to respond to the output thereof, that of the first circuit trigger to effect valve opening and that of the second circuit trigger to effect valve closing.
- 12. Irrigation apparatus for an area, said apparatus including a water supply, a pump in control thereof and including a motor and a motor circuit, a conduit in communication with said area and with said supply, each conduit including a valve, and a control for said valve and said pump including a pair of contacts to be inserted in the soil, first and second circuits and input leads, one input lead including a resistor string and a capacitor, leads of substantial length connecting said contacts to said one input lead across said capacitor, said string including first and second adjustable resistors, the first establishing a dry threshold and providing an input for the first circuit and the second establishing a wet threshold and an input for the second circuit, each circuit including a Schmitt trigger and means operable in response to the monitored threshold to deliver shaped pulses thereto, a third circuit includes means operable to effect the opening and closing of said valve and means connected to each trigger to respond to the output thereof, and circuitry including a switch in said pump motor circuit and means connected to and controlled by the first circuit to effect the closing of said switch at the monitored threshold and means connected to said third circuit and controlled by the output of the second circuit trigger to effect the opening of said switch at the monitored threshold.
Specification