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SCIENTIST who invented the dimmer switch

• Joel Spira, physicist. Born: 1 March, 1927, in New York. Died: 8 April, in Coopersburg, Pennsylvania, aged 88.

Joel Spira, who changed the ambience of homes around the world and encouraged romantic seductions of all types when he invented the first lighting dimmer for domestic use, has died in Coopersburg, Pennsylvania. He was 88.

Spira was a physicist working for a military contractor in the late 1950s when, puttering in a spare room of his Manhattan apartment, he invented a way to reduce the light output of an incandescent bulb. The device spurred the creation of Lutron Electronics, a lighting-control company he started in Emmaus, Pennsylvania, in 1961 with his wife, Ruth; it was granted its first patent for a solid-state dimmer in 1962.

Relocated to Coopersburg, in 1970, Lutron became a leader in the lighting control business. It employs more than 1,000 people and distributes myriad products, including dimmers, automated window treatments (shades that go up and down according to sunlight, for example), fan controls and home- and building-control systems. Devices to control the intensity of a light source existed before Spira’s innovation, but they were unsuitable for home use. Large and unwieldy, they consumed great amounts of energy and gave off a lot of heat, so they were restricted to certain commercial functions, like regulating the stage lights in theatres.

Spira’s idea was to replace a rheostat, which controlled the current flow in an industrial dimmer by absorbing electrical energy on its way to a light source, with a thyristor, a type of transistor that interrupted the flow of power to the light.

The change made the dimmers cooler and small enough to fit in a home wall box. They also used less electricity. A prime selling point for dimmers and other lighting-control products has been that they save energy. Lutron’s original marketing strategy was considerably sexier, however. Its first commercial product was called the Capri, a dimmer switch operated by a lighted dial implanted in an 18-inch-high wall panel, and its store displays featured a drawing of a shapely woman in a sleeveless pink evening gown. Subsequent sales pitches capitalised on the idea of low lights and privacy. In one ad, a well-dressed couple hold hands and exchange longing glances beneath a chandelier.

“Dial romance,” the copy reads, “with a light dimmer Dim’n’Glo.”

Joel Spira served in the Navy as a radar designer at the end of the Second World War and graduated from Purdue with a degree in physics.

In addition to the Capri, Spira and Lutron created a dimmer switch controlled by a sliding tab (he called it the Nova) as well as the first infrared remote control dimmer, the first whole-home lighting-control system and a system of motorised window shades marketed as Serena.

Spira married Ruth Rodale in Emmaus in 1954. She survives him, as do their three daughters, a sister and three grandsons.

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