Parasitic power supply for traffic control systems

Abstract

A parasitic power supply provides for drawing power for an auxiliary device from a set of sequentially driven loads. A typical source of power is a traffic signal wherein the power may be sequentially applied to red, green and yellow lamps. The design provides isolation between loads so no two loads will be powered through any single-point failure of the power supply. The device may further contain control elements such as time delays to make the system compatible with requirements of safety devices used in traffic control systems to sense burned-out bulbs, and to sense conflicts between lighting patterns that are supposed to be mutually exclusive. The device may be configured as a separate component, or it may be integrated into a traffic signal head or into any selected device intended for connecting to a traffic signal head. The invention is particularly suitable for standard systems operating nominally at 115 VAC, though other AC voltages, and direct-current supplies, can also be used.

Dependencies are inferred from the claim text.