Abstract: The present invention provides a Control Module 15 for controlling a dual filament bulb, in particular aircraft reading lamps, so as to detect the failure of one filament and energize the other filament. The Control Module 15 also has provisions for detection of bulbs that have only one or no operable filament(s) by activating an indicator (Light Emitting Diode) or connection to a test switch that will command the Module to activate bulbs that have two operable filaments only. The Control Module 15 consists of a solid state circuit made up of triacs, resistors, capacitor, diodes and fuse all packaged in a small printed circuit board. Interface between the Module and dual filament bulb, indicator or test switch is easily accomplished by a small connector on the Control Module 15.

Abstract: A digital phase sequence detector which operates completely independent of signal amplitude values to provide an output signal having a logic level indicative of which of two phasors being compared is leading. The detector develops first and second feedback signals which determine the stable state of the circuit. This feedback arrangement enables the detector to be constructed of standard integrated circuits devoid of flip-flops or other memory elements requiring a clock. The level of the output signal of the detector persists for as long as the relationship being indicated persists, eliminating the need for pulse stretchers, timers, or the like.