Abstract: A timing circuit is provided comprising a light sensing component operable to generate a raw solar signal, a solar signal regulator comprising a voltage regulator and a low-pass filter, the solar signal regulator coupled to the raw solar signal and generating a regulated solar signal, a comparator coupled to the regulated solar signal and a reference value, the comparator configured to assert a solar output signal when the regulated solar signal exceeds the reference value, and a timing circuit coupled to the solar output signal and configured to assert a timer output signal a preset delay duration after the solar output signal is asserted, and to maintain the timer output signal for a preset output duration.

Abstract: A control switch for controlling the operation of an overhead irrigation system based upon the moisture level of the ground in an area to be irrigated. The control switch includes first and second moisture detection probes positioned at first and second underground locations in the area to be irrigated, which, upon detection that the soil is dry, place a positive conductive charge on the switch, thereby turning on the irrigation equipment. Upon detection that the soil is wet, the probes remove the conductive charge, thereby turning off the irrigation equipment. The control switch provides varying degrees of sensitivity to soil moisture, and varying time delays in turning the switch on when the soil is dry, and in turning the switch off when the soil is wet. A pulsing current protection circuit permits a positive DC signal taken from an AC triac to turn on the triac when both the AC and DC portions of the control switch share a common ground.