Control for lawn sprinkler

Claim 2

A control system for a lawn sprinkler including a base which delivers a desired amount of water to a lawn area comprising: a. a water sensing device including a nonconductive tank secured to the base of the sprinkler for collecting water from the sprinkler and from atmospheric precipitation; b. electrical means for sensing the water level in the tank, said means including at least two terminals which pass current through the water only when the collected water has reached a predetermined height in the tank and wets both terminals; c. an amplifier having input and output circuits, the input circuit connected to said tank terminals and arranged to provide a current in its output circuit only when the input circuit is bridged by water; d. a relay having its winding connected to the output circuit of said amplifier and a pair of normally closed contacts which are opened when the relay is activated; and e. a solenoid water valve for turning the sprinkler water on and off, comprising a valve connected in a water supply hose which sends water to the sprinkler and a solenoid winding connected to said relay contacts in series with an electrical power supply.

Claim 3

A sensing device according to claim 1 wherein said tank is provided with three terminals, a first pair of terminals for activating the relay and latching it in its actuated condition to turn off the water and a second pair of terminals for unlatching the relay to turn on the water after the water level has dropped to a predetermined level.

Claim 4

A sensing device according to claim 2 wherein said relay includes a pair of normally open latching contacts which are closed when the relay is actuated, said contacts connected in series between one of the three tank terminals and a portion of the amplifier.

Claim 5

A control system for a lawn sprinkler which delivers a desired amount of water to a lawn comprising: a. a water sensing device including an absorbent material which is nonconductive when dry but conductive when wet, said sensing device comprising a Y-shaped insulator having two upper prongs and a pointed base shaft positioned adjacent to the sprinkler and adapted to receive water from the sprinkler when the water is turned on, said absorbent material connected between the upper prongs of the insulator; b. electrical means for sensing the conductivity of said material, said means including two electrodes connected to said material in spaced relation; c. an amplifier having input and output circuits, the input circuit connected to said electrodes and arranged to provide a current in its input circuit only when the resistance between the electrodes falls below a predetermined value; D. a relay having its winding connected to the output circuit of said amplifier and a pair of normally closed contacts which are opened when the relay is actuated; and e. a solenoid water valve for turning the sprinkler water on and off, comprising a valve connected in a water supply hose which sends water to the sprinkler and a solenoid winding connected to said relay contacts in series with an electrical power supply.

Claim 6

A control system for a lawn sprinkler which delivers a desired amount of water to a lawn comprising: a. a water sensing device including an absorbent material which is nonconductive when dry but conductive when wet, said sensing device comprising a Y-shaped insulator having two upper prongs and a pointed base shaft positioned adjacent to the sprinkler and adapted to receive water from the sprinkler when the water is turned on, said absorbent material connected between the upper prongs of the insulator; b. electrical means for sensing the conductivity of said material, said means including two electrodes connected to said material in spaced relation; c. an amplifier having input and output circuits, the input circuit connected to said electrodes and arranged to provide a current in its input circuit only when the resistance between the electrodes falls below a predetermined value; D. a relay having its winding connected to the output circuit of said amplifier and a pair of normally closed contacts which are opened when the relay is actuated; and e. a solenoid water valve for turning the sprinkler water on and off, comprising a valve connected in a water supply hose which sends water to the sprinkler and a solenoid winding connected to said relay contacts in series with an electrical power supply.