Glow discharge lamp

Claim 1

A glow discharge lamp having an electronic circuit for regulating lamp output according to changing environmental conditions comprising: a light transmitting envelope containing mercury and a noble gas fill; an anode disposed in said envelope having a single lead-in wire; a cathode lamp filament located within said envelope having a pair of lead-in wires; a power lamp circuit electrically connected between said anode lead-in wire and said cathode for creating a lamp voltage; a filament power circuit electrically connected to said pair of cathode lamp filament lead-in wires for creating a filament voltage whereby said lamp voltage decreases with an increasing filament voltage; a sensing and control circuit including a lamp start up circuit for limiting control circuit current and voltage during startup, said sensing and control circuit being adapted for adjusting the filament voltage in accordance with changing environmental conditions for maintaining lamp voltage at a predetermined constant value from about 11 to about 16 volts; and said sensing and control circuit including means for detecting lamp voltage in excess of said predetermined value and means responsive to said detecting means for increasing said filament voltage for reducing said lamp voltage to said predetermined value.