A device for providing an orderly shut-down of a system of interconnected traffic lights upon loss of its primary electrical power is disclosed. A device for permitting consistent reapplication of power to a line conditioner having a ferroresonant transformer is also disclosed. Further, a battery charger for charging a battery system including a plurality of battery cells coupled in series is disclosed. Additionally, a device for determining proper operation of a power transistor by monitoring its saturation voltage and emitter current is also disclosed. Finally, a device for generating a first alternating signal in-phase with a separately generated second alternating signal is disclosed.
A signal processing apparatus is provided for processing first and second periodic analog signals having the same period and having a fixed phase relationship therebetween. The apparatus includes an A/D converter for converting respective amplitudes of the first and second periodic analog signals into first and second digital signals. The apparatus also includes a phase digitizer for generating a signal from the first periodic analog signal, the generated signal having a period that is shorter than the period of the first periodic analog signal, and a high speed signal processing portion for generating from the generated signal a periodicity and first phase information of the first periodic analog signal. The apparatus further includes a another signal processor for producing second phase information of the first periodic analog signal from the first and second digital signals, and for correcting the periodicity on the basis of the first phase information and the second phase information.
An LED traffic signal with a display indicating the remaining interval for the current display mode. A switching power supply provides cost of manufacturing and operational efficiencies. Interference with logic circuitry normally associated with switching power supplies is prevented by noise filtering circuitry and isolated ground planes on the printed circuit board.
