Halostar KLR51 1st Gen. - 41870FL M50 EXZ

During the early 1980s, a number of European lighting designers began experimenting with low voltage MR16 dichroic projection lamps for accent lighting of retail interiors. Previously the incandescent sealed beam PAR and blown reflector R lamps had dominated this market, but the new low voltage lamps introduced a powerful arsenal of features. Perhaps the most noteworthy are their compact dimensions, whiter light, a cool beam thanks to the dicroic coating, an attractive sparkling effect from the multi-facetted mirror. As if this wasn't enough, their high efficacy also permits the same lighting effect to be achieved from a single 50W low voltage lamp as from a 100W PAR38 reflector. The lamp featured on this page was Osram's first offering for low voltage accent & display lighting markets.

The design is clearly based on the company's standard products for photo-optic and projector applications. Even the reflector is of a type better suited to short focal distance lamps for slide projectors. In order to achieve the narrower beam angles (thus longer focal distance) required for spotlighting, the filament position in the reflector has been slightly de-focussed. Ordinarily this would result in some inhomogeneity of the beam with a dark spot at the centre, however the problem here has been solved by sandblasting the surface of the halogen capsule to present a more diffuse source. This does make the lamp rather inefficient though, and its beam intensity is somewhat lower than competitors products which employed a dedicated reflector for the required beam distribution. By 1988 Osram followed suit with a range of lamps having specially designed reflectors. These were launched under the Decostar name, which superseded these former Halostar KLR products.
Manufacturer: Osram GmbH
Lamp Power: 50 Watts  
Lamp Voltage: 12 Volts  
Lamp Current: 4.16 Amperes  
Cap Type: GX5.3 Round glass base
Bulb Type: MR-51 MR-16 in eighths/inch
Bulb Finish: Open Front Dichroic Mirror
Filament Type: C-6 Transverse single coil
Atmosphere: Krypton:Argon Bromine cycle
Luminous Flux: 950 lm (capsule flux)
Luminous Efficacy: 19.0 lm/W (capsule efficacy)
Peak Intensity: 2,800 candelas to half-peak intensity
Beam Distribution: 20.0 x 20.0° to half-peak intensity
Colour Temperature & CRI: CCT: 3000K CRI: Ra 100
Chromaticity Co-ordinates: CCx: 0.452 CCy: 0.409
Rated Lifetime: 2000 hours to 50% survival
Burning Position: Universal  
Overall Length: 44 mm 1¾ "
Light Centre Length: N/A
Factory: Eichstatt Germany
Date of Manufacture: January 1986 it0
Original / Present Value: GB £7.71 trade (1988) £14.90 (2007)
References: 1) Wotan Brochure "Halostar Lamps" - November 1984
2) Osram-GEC - UK Price List April 1988