Ballast circuit for lamps with low voltage gas discharge tubes

Abstract

A ballast circuit arrangement for providing a predetermined desired A.C. voltage to enhance the operation of the gas discharge tube serving as the main light source in a lighting unit of the type which also comprises an incandescent filament serving as a resistive element and a supplementary light source is disclosed. The circuit arrangement operates directly from an applied 220 volt, 50 Hz or 120 volt, 60 Hz alternating current (A.C.) voltage source. The circuit arrangement comprises a capacitor connected serially with both the incandescent filament and the gas discharge tube. If desired, the incandescent filament may be replaced with a resistive element. The value of the capacitor is selected so as to reduce the applied 220 volt, 50 Hz or 120 volt, 60 Hz A.C. source to a desired range for operating the circuit in a manner to develop a desired reduced voltage for operation of the gas discharge tube. The reduced operating voltage correspondingly reduces the restrike voltage that may be necessary to operate the gas discharge tube during restrike conditions. The reduced operating voltage of the gas discharge tube readily allows for the development of the restrike voltage directly available from the typical 220 volts, 50 Hz or 120 volts, 60 Hz A.C. source. The circuit arrangement further provides for an automatic restrike voltage under reduced voltage A.C. source conditions.