Flashing light indicator - has light sensitive devices to vary intensity according to surrounding light

摘要

The indicator is designed to mark emergency installations, danger points on roads etc. Energy is economically used by varying the intensity of the lighting according to changing light conditions of the surroundings. The maximum intensity is required at dusk when the flashing indicator is to be recognised at a distance. Light sensitive devices are switched off during daylight hours, reach maximum capacity at dusk, and then gradually decrease in strength as it becomes darker. In a first embodiment a photo-electric cell switches off the supply when daylight falls upon it. A second light sensitive device has a resistance that varies according to the effect of light so that current flow correspondingly changes. The length of the flash can also be modified.