This is an excerpt from S. Baldwin, H. Hamilton, M. Shorter and J.W. Suh, " The Smart Light," ECE 4512: Design I, Department of Electrical and Computer Engineering, Mississippi State University, Fall 2003:

This project seeks to create The Smart Light, a low-power streetlight sensor that will prevent false alarms from lighting bursts and car headlights and will regulate the power sent to the light bulb in reaction to the amount of external light. Perhaps the most ambitious aim of this project is to design this sensor to fit in a package the same shape as competitors: current sensors contain few parts, usually three to five, and therefore can easily fit into a package measuring two inches height and three inches diameter [2], whereas The Smart Light will contain up to eight substantial components that require adequate spacing between one another for heat dissipation. The main functional constraint of the project is that The Smart Light must wait ten seconds upon sensing a change in light intensity before deciding to activate or deactivate the light bulb. This time period was chosen since it is longer than the duration of a lightning burst and exceeds the amount of time headlight beams could shine directly on the sensor. During this ten-second period, The Smart Light will continuously monitor the incoming light to ascertain whether the fluctuation is constant or transitory. Another constraint defining the operation of the sensor is that it must operate the light bulb in reaction to the amount of external light: for example at dusk, the sensor will provide the light bulb a lower percentage of voltage than it will at midnight, thus conserving power in situations not requiring maximum power output of the light bulb. The most sweeping constraint of this project is that it must provide all of this functionality and reliability while only consuming one Watt of power, a quantity far below competitor specifications [3].