1906 · Silicon Crystal Detector · Work 803 of 1,871
A crystal detector of 1906 on a wooden table in a coastal radio station in New England, a polished brass stand eight centimetres high, at its base a small copper-plated brass cup holding a matt silvery-grey lump of silicon, above it on a brass ball joint a slender brass sleeve carrying a fine springy wire point that rests on the lump, beside it a large coil of bare copper wire on a wooden frame, a headset with a leather band, a hand in a dark blue wool sleeve adjusting the ball joint, a window onto grey water, light from the right.
What it was used for
Greenleaf Whittier Pickard tested thousands of mineral samples for rectification between 1902 and 1906; silicon crystals from Westinghouse gave some of the best results, according to the Computer History Museum. His patent 836,531 was filed on 20 August 1906 and granted on 20 November 1906. With two partners he founded the Wireless Specialty Apparatus Company, which sold such detectors.
What was new
The crystal contact rectified without a power source - simple receivers worked on no external energy. Pickard was neither the first nor the only one: Bose had filed a point-contact rectifier using galena in 1901 (US 755,840, granted 29 March 1904), Dunwoody's carborundum patent 837,616 followed 2 weeks after Pickard's on 4 December 1906, and Torikata received Japanese patent 15345 in 1908. The barb: the sensitive spot had to be found again by hand, and by the mid-1920s valves displaced the crystal in most applications - until the same point contact returned for microwave radar in the Second World War.
What the sources leave open: The Computer History Museum speaks of "thousands" of samples and gives no exact count; a figure of 30,000 in circulation could not be verified. Statements on the company's buyers and market share appeared only on a page that describes itself as an AI summary; they are therefore not used.