Importance

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Abstract

A succession of emergency-phone stations distributed along the length of a communications cable laid alongside a highway is powered from a remote central station. The phone stations are provided with lamps to form a blinking-lamp signalling system warning of upcoming traffic hazards. Each phone station's blinking system includes a code-evaluator circuit stage which interprets code signals transmitted along the power-supply circuit of the communications cable, the code signals identifying which stations are to have their lamps blink and in accordance with which blinking schedules. Each station is provided with a bistable activation stage which responds to the first occurrence of a transmitted-voltage boost by disconnecting from power the code-evaluator circuit stage of all flashing stations, and all circuitry of all non-flashing stations, but which reconnects to power upon the second occurrence of such voltage boost. The voltage boost is performed after the transmission of the code signals as blinking action actually commences, and is performed a second time when blinking action is terminated. The bistable activation stage at each station is permanently connected to power but draws virtually zero power except when a protracted interval of blinking action is initialed and terminated.

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First Claim