Behrooz Bakhshaei
Engineers at Anadale Dr, Laguna Beach, CA

5148826, Sep 22, 1992

Sep 3, 1991

7/753782

Behrooz Bakhshaei - Laguna Hills CA

A01G 2516

137 80

There is provided a system for monitoring moisture level in soil and controlling application of water to the soil. The system includes a moisture level sensor which generates a small voltage through the Volta effect. This voltage is amplified and is then used to trigger a switch typically connected to a standard watering timer. The sensor signal may be compared to a present voltage level through a comparator, and in this way the amount of moisture in the soil which will determine the "on" condition can be selected. The preferred sensor in the present invention is a bimetallic element, the soil functioning as an electrolyte in contact with the bimetallic element such that a Volta effect electromotive force is produced in the bimetallic element. A temperature sensor is also included, and functions in parallel to the moisture sensor such that both moisture level and temperature level must be within a present range in order for the comparator to pass an output signal on to the switch. Multiple sensors may be used in a configuration that allows each sensor or pair of sensors to control one set of watering devices so that various preconditions may be set for different zones of soil to be watered.