Single Ended Halogen Capsule - A1/215 FCR
The earliest tungsten halogen were made in the form of a linear quartz tube, pinched closed at both ends around an axial filament. While this arrangement was perfectly suitable for large area floodlights, they lacked the point-like nature of conventional lamps. Additionally, their production required the fabrication of two glass-to-metal seals, which were rather difficult and expensive to form at this time.

In 1961 the work of J.A. Moore at the Hirst Research Labss of GEC at Wembley was published, in which H.G. Jenkins presented the company's invention of the Single Ended Low Voltage halogen lamp. By pinching both tails of the filament into a single seal the contruction was simplified, and the introduction of a low voltage filament made the lamp remarkably compact. The world's first lamp made according to this design was the type A1/215 (FCR) shown here. It is a 12V 100W capsule having a flat mandrel filament, intended for slide projection applications. The GEC promoted this new innovation to the UK projector manufacturers such as Aldis, but astonishingly they showed little interest. The company therefore focussed on the retrofits market supplying adaptors such as the type illustrated here, which allowed them to replace various incandescent types such as the A1/186 and its pre-focussed version, the A1/193.

Curiously the European manufacturers showed much more interest in halogen lamps, and here Thorn Lighting had stronger contacts. It ably exploited the GEC's single ended concept and was first with a halogen lamp for 8mm cine projection, produced for Eumig. GEC meanwhile went on to achieve a position of leadership in other markets, such as the use of these capsules in airfield and automotive lighting.
Manufacturer: The General Electric Company of England, PLC
Lamp Power: 100 Watts  
Lamp Voltage: 12 Volts  
Lamp Current: 8.33 Amperes  
Cap Type: GY6.35 Molybdenum pins
Bulb Type: T-10.5 T-3.5in eighths/inch
Bulb Finish: Clear Quartz
Filament Type: FC-6 3.5 x 2.5mm
Atmosphere: Iodine in Ar
Luminous Flux: 3000 lm  
Luminous Efficacy: 30.0 lm/W  
Peak Intensity: N/A  
Beam Distribution: N/A  
Colour Temperature & CRI: CCT: 3300K CRI: Ra 100
Chromaticity Co-ordinates: CCx: 0.452 CCy: 0.409
Rated Lifetime: 50 hours to 50% survival
Burning Position: Universal  
Max. Overall Length: 44 mm 1 3/4"
Light Centre Length: 30 mm 1 3/16"
Factory: Wembley United Kingdom
Date of Manufacture: July 1966 Date Code XG
Original / Present Value: Unknown
References: 1) Osram-GEC Lamp Catalogue, UK, 1975, p.50
2) The Tungsten Halogen Lamp Decade, R. Burgin & E.F. Edwards, Lighting Research & Technology V.2 No.2 pp.95-107, February 1970
3) Private Communication, Ray Burgin, March 2008