Ambient light monitoring system

Abstract

This invention includes a sensor, a time delay trigger circuit, and a power source. The sensor monitors an ambient light level and produces a sensed signal related to the ambient light level. The time delay trigger circuit is in electrical communication with the sensor for determining whether the ambient light level remains reduced below a predetermined level for a specified time. The time delay trigger circuit includes a counter/timer circuit, a comparator circuit, a timing gate circuit, and an output driver. The counter/timer circuit receives the sensed signal from the sensor and initiates a count sequence when the ambient light level is below a predetermined level. The counter/timer circuit provides a count value output representing elapsed time. The comparator circuit includes a plurality of switches used to set the specified time delay. The comparator circuit compares the count value output from the counter/timer circuit with the switches. The comparator circuit provides an output indicative of the comparisons. The timing gate circuit receives the output from the comparator circuit. The timing gate circuit is in communication with the counter/timer circuit to stop the count sequence when the comparator circuit output indicates that the count value output from the counter/timer circuit equals values set by the plurality of switches. The count value output is a binary coded decimal (BCD) output. The output driver includes an output triggering circuit for receiving the output from the comparator circuit, for holding the trigger state and for providing a drive signal. An output interface of the output driver includes at least one electrical system output for receiving the drive signal. The electrical system output is connectable to a desired electrical system.