Abstract: A method of estimating the occurrence of midnight on a given day comprises the steps of determining the average night length (NLAVE) by averaging the night lengths (NL) between a night starting time (NST) as determined by a photosensor and a night ending time (NET) determined by a photosensor for each of a plurality of days, and estimating midnight to occur at the time that is one half of the average night length (NLAVE) after the night starting time (NST) for the given day. This estimate of midnight to control the operation of lights or other equipment without the need for clocks or constant power.

Abstract: A method of estimating the occurrence of midnight on a given day comprises the steps of determining the average night length (NLAVE) by averaging the night lengths (NL) between a night starting time (NST) as determined by a photosensor and a night ending time (NET) determined by a photosensor for each of a plurality of days, and estimating midnight to occur at the time that is one half of the average night length (NLAVE) after the night starting time (NST) for the given day. This estimate of midnight to control the operation of lights or other equipment without the need for clocks or constant power.

Abstract: A quartz oscillator-driven time-measuring circuit normally and substantially continuously updates the time display of a clock. A control circuit independent of the time-measuring circuit receives the standard time interval pulse signal broadcast by WWV/WWVH which includes longer pulses signaling each minute and shorter pulses signaling the seconds between minutes. The control circuit includes mechanism activated by the longer minute pulses to set the clock display intermittently, i.e. once each minute. Between minutes, the time-measuring circuit updates the clock display.