Lighting unit
 An energy efficient lighting unit is described designed for functional similarity to the incandescent light used in the home. The light unit utilizes a metal vapor arc lamp as the main source of light supplemented by a standby filamentary light source. The lighting unit includes means for converting 60 hertz ac to dc, and a dc energized operating network comprising an inverter operating at above audible frequencies (e.g. 30-40 KHz). The operating network produces a sequence for the arc lamp and the standby filamentary light source appropriate to each operating state of the arc lamp. 
General Electric Company
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H05B Y10S H05B H05B Y02B Y10S
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James E. Thomas A. William
Harris Brown Peil