1953 · Surface-Barrier Transistor · Work 821 of 1,871
A tiny transistor of 1953 under a magnifier lamp on a black hard rubber plate at a test bench in a valve factory in Pennsylvania, a bullet-shaped metal case one centimetre long and three millimetres thick, its rounded tip bright silver, its body wrapped in a plain smooth band of yellowish-brown paper, a dark base at its flat end with three thin bent silver wires, beside it a flat tray with a bed of cotton wool holding a dozen identical cases, tweezers in a hand in a white cotton glove, a black Bakelite microscope, grey daylight through a window with glazing bars.
What it was used for
Philco introduced the surface-barrier transistor at the end of 1953; the company paper Philco News of January 1954 reports the presentation at the Franklin Institute and names as the target application a portable military VHF receiver running on 2 flashlight cells and as small as a pack of cigarettes. It was made by electrolytically etching and then electroplating the electrodes, not by alloying. Philco's application note of November 1955 lists low-level video amplification, high- and medium-frequency amplifiers, oscillators and frequency converters, and holds the type especially suited where large numbers of high-speed devices are involved, as in computers. The arithmetic unit of the Philco TRANSAC was built in 1955 from about 1,700 transistors in under 300 cubic inches and needed less than 8 watts.
What was new
The difference is in the company's own words of January 1954: the device works at frequencies 10 to 100 times as high as obtainable with the older alloy junction transistors. The 1955 application note gives the SB-100 an alpha cutoff of 45 mc, amplifier bandwidths variable from 2 to 12 mc, and rise and fall times under one-tenth microsecond for a flip-flop circuit; in general the type operates at 4.5 volts or less. The process was not held alone: a patent by Arthur A. Varela, filed 11 May 1954 and issued 15 July 1958, takes the etching process described in the December 1953 Proceedings of the IRE as the state of the art and objects that the etching times are exceptionally critical. Units that failed the requirements of other SB types were, as the Transistor Museum surmises, sold to hobbyists as the A01; the 1957 Lafayette Radio catalogue lists the A01 for $1.90, the lowest price of all SB types sold.
What the sources leave open: The series of papers in the December 1953 Proceedings of the IRE could not be located; all Philco figures come from the company's own publications. Unit numbers, revenue and temperature limits are not documented. John Wallmark, often named as a participant, appears in no source opened; Philco News names Leslie J. Woods, William E. Bradley and William H. Forster.