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This lamp is an engineering sample of the GE Halarc Miser Maxi-Light, specially produced with a clear glass bulb and transparent plastic base to reveal its internal construction. It was a few decades ahead of its time, marking the first ever attempt to bring the efficacy of metal halide into home lighting. Its development was fuelled by the work of GE's Elmer Fridrich on low wattage metal halide, and the energy crisis of 1973. GE managers saw an opportunity to engineer his ideas into a retail lamp that would halve energy usage.
At the heart of the lamp is a 32-watt sodium-scandium arc tube. To attain a warm colour light of 3200K for domestic use, it is operated on DC with the anode uppermost so as to draw sodium ions up into the arc stream. A quartz shroud helps to minimise sodium loss and keep colour stable during life. An incandescent filament is also included in the outer bulb. This provides instant light, even after a hot-restart while the arc tube is cooling, and helps miniaturise the electronic ballast by reducing the size of magnetic parts. The assembly is mounted on an 8-pin glass wafer stem, and sealed into a soft glass bulb with argon-nitrogen fill, plus a diffuse coating to mix the light from the filament and arc.
By the time GE completed development the energy crisis was over, and the competing Philips' SL lamp with compact fluorescent technology just beat it to the market. That overcame many of the drawbacks of compact metal halide technology, namely no colour instabilities, a pronounced flicker, restriction to vertical base down use, and the very high sale price. Despite millions of dollars of investment, GE's lamp was not popular and was withdrawn by 1984. It's arc tube however lives on in the Halarc 32 watt lamp. |