Abstract: A circuit for energizing either a first or second lamp and for energizing a motor to position the energized lamp is comprised of first and second switches for supplying current to one of the lamps. Current sensors are provided to monitor the flow of current through each of the lamps. When current is flowing through one lamp and its associated switch, a biasing network assures that the other switch remains open. Upon the failure of the energized lamp, the other lamp is energized, a motor is energized so that the other lamp may be moved to a desired position within the optical system, and a visible indication that the lamp has failed open is provided.

Abstract: A controller for controlling operation of a multi-filament lamp is provided that permits selection of the filament to be energized from a control box placed at a remote location from the lamp. Only two leads are required to electrically connect the control box to the lamp. The controller automatically switches energizing power from a burned out filament to an alternate filament. The controller can also include a source of alternate power for the controller in the event that primary power is lost. The controller can also include a lock out feature which prevents switching energizing power at the control box from an energized filament to a failed filament.1. Field of the InventionThe present invention relates to controllers for lamps and, in particular, a controller for a lamp having more than one light source that permits control of the lamp from a location remote from the lamp.2.