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Goebel claimed his lamp contained a high resistance filament of carbon, platinum lead-in wires in an all-glass envelope, and a high vacuum produced with the Torricellian method using mercury. He tried several materials to produce the carbon filaments and discovered the advantages of bamboo.
The bulb was made by hand, using a carbon filament (of greater thickness and strength than the tungsten filaments used in most modern lightbulbs) along with brass and glass components of high quality. The low wattage (originally 60 watts, now approximately four) and high nitrogen atmosphere inside the bulb have also contributed to its longevity.
UN Regulation 37 covers motor vehicle filament lamps. These are categorized in three groups: those without general restriction that can be used in any application, those acceptable only for signalling lights (not for road illumination lamps), and those no longer allowable as light sources for new type approvals but still permitted for production as replacement parts.
In the 1980s, after watching a salvage operation, Bob Rosenzweig started the reproduction and selling of his faux-antique bulbs. [9] These vintage-style light bulb reproductions were sold mostly to collectors and prop houses, and continued until the turn of the 21st century when new regulations banned low-efficiency lighting in many countries.
Lodygin later sold the patent rights to GE. In 1902, Siemens developed a tantalum lamp filament that was more efficient than even graphitized carbon filaments since they could operate at higher temperature. Since tantalum metal has a lower resistivity than carbon, the tantalum lamp filament was quite long and required multiple internal supports.
The company dropped the campaign in 1945. GE's patents on the tungsten filament lamp expired in the late 1930s, and other forms of lighting were becoming more important than incandescent bulbs. [citation needed] GE stopped licensing the trademark to other manufacturers, although it continued to renew the trademark registration up to 1990.