1981 Philips 7786R (1 kW)

Introduced in 1970, the Philips 7786R tungsten halogen lamp was specifically designed to meet the demanding lighting requirements of movie sets and television studios. Its 3200 K light color temperature made it ideal for a use with tungsten-balanced color films and electronic cameras, ensuring a consistent image quality throughout its lifespan. The lamp features a compact coiled coil tungsten filament measuring just 70 mm in length and operating at 1 kW. It is filled with a carefully balanced atmosphere of nitrogen, krypton, and an active mixture of dibromomethane and iodine, which maintains a constant light output at a high filament temperature. The latter results in an impressive luminous efficacy of 27 lm/W.

Remarkably, the 7786R shares the same configuration and dimensions as those of standard 500 W tungsten-halogen lamps, measuring 117.6 mm in length and 11 mm in diameter, and fitted with R7s end caps. Despite its compact size, this source delivers 27,000 lumens - 2.7 times more than a 500 W lamp’s 9,900 lumens - allowing smaller and more efficient luminaires. To ensure proper safety, fuses integrated into the lamp's moly foil end seals (see the additional cavities) prevent current surges and internal arcing in the event of filament rupture at end of life. Such precaution is necessary as this failure mode is very likely to happen with such compact filament operating at high temperature.

The lamp was manufactured in Belgium during a period when Philips’s Turnhout factory specialized in halogen lamp production. Initially, the 7786R had a service life of 200 hours, but subsequent improvements extended this to 300 hours while the lumen output was increased from 25,000 to 27,000 lumens. Because of its use of iodine and krypton, which is prone to cause segregation in the gas mix, the tolerance on the lamp’s horizontal operation is limited to ±4° only. Such limitation was deemed acceptable in regard of the benefits in terms of light color and output brought by the lamp’s fill chemistry, which made this particular source a groundbreaking choice for professional studio lighting compared to standard lighting solutions employing filter gels.