Abstract A pair of probes are placed in soil, the watering of which is to be controlled, the electrical resistance between the probes being a function of the moisture content of the soil. The probes are connected in the feedback circuit of an electronic oscillator, the magnitude of oscillation of the oscillator being a function of the resistance between the probes and thus the soil moisture content. The output of the oscillator is fed to a comparator circuit where it is compared with a reference voltage representing a predetermined moisture level. A control signal is generated in the comparator circuit whenever the soil moisture content is below the predetermined level during the periodic checkup, this control signal operating a warning signalling circuit. After a predetermined time has elapsed, during which a warning signal is generated, a watering control circuit is actuated which effects the watering of the soil for a predetermined period of time. In cases when manual operation is desirable or if automatic controll fails provision has been made for manually controlled operation.
Electronically controlled watering comprising: a pair of probes placed in the soil, the electrical resistance between said probes being a function of the moisture content of the soil, an electronic oscillator, said probes being connected in the feedback circuit of said oscillator whereby the magnitude of the voltage output of said oscillator is proportional to the soil moisture content, means for generating a reference voltage representing a predetermined moisture content, means for comparing said reference voltage with the voltage output of said oscillator and generating a control signal whenever the moisture content of the soil falls below the moisture content represented by the reference voltage, and means responsive to said control signal for controlling the watering of the soil.
Claim 2
Dependent Claim
119 words
Electronically controlled watering comprising: a pair of probes placed in the soil, the electrical resistance between said probes being a function of the moisture content of the soil, an electronic oscillator, said probes being connected in the feedback circuit of said oscillator whereby the magnitude of the voltage output of said oscillator is proportional to the soil moisture content, means for generating a reference voltage representing a predetermined moisture content, means for comparing said reference voltage with the voltage output of said oscillator and generating a control signal whenever the moisture content of the soil falls below the moisture content represented by the reference voltage, and means responsive to said control signal for controlling the watering of the soil.
Claim 3
Dependent Claim
44 words
The system of claim 1 and further including a signalling circuit responsive to said control signal for generating a watering warning signal during a predetermined time period, said means for controlling the watering of the soil being operative after said time period has elapsed.
Claim 4
Dependent Claim
45 words
The system of claim 1 wherein said means for controlling the watering of the soil includes a watering control circuit and relay means responsive to the control circuit for effecting the watering action, said control circuit actuating said relay means during a predetermined time period.
Claim 5
Dependent Claim
30 words
The system of claim 1 and further including means for sensing the presence of rain on said soil and preventing the watering of the soil whenever a rain condition exists.
Claim 6
Dependent Claim
49 words
The system of claim 3 and further including means for sensing day to night and night to day change in the ambient light level and inhibiting the operation of said watering control circuit at all times except during a period of time after such a change has been sensed.