1953 · Hobbyist Junction Transistor · Work 822 of 1,871
A small transistor of 1953 on a hobby table in a house in an American suburb in the afternoon, a young hand in a checked cotton sleeve holding with tweezers a plain smooth unmarked block of matt black resin six millimetres wide and nineteen millimetres high with rounded upper corners and three straight parallel silver wires, above a piece of brown pressboard with screwed-on solder tags, beside it a coil of wire wound on a cardboard tube, a small variable capacitor with aluminium plates, a black Bakelite headset, a soldering iron in a wire stand, daylight through a window with a curtain.
What it was used for
Raytheon offered the CK722 germanium junction transistor expressly to experimenters. The advertisement in Radio-Electronics of February 1953 says the germanium junction transistors CK721 and CK722 can now be obtained for the reader's own experimental and developmental use, and claims that for the first time in history such transistors are commercially available. Per IEEE Spectrum they were available through RadioShack stores from March 1953. The CK722 museum lists hobby projects including radios, oscillators, electronic voltmeters, photoelectric alarms and hearing aids; the Transistor Museum records that the type was used not only by hobbyists but also in commercial radios of the 1950s. The price was $7.60 in February 1953, $1.00 in 1956, and, for surplus units, 10 for $1.00 in the early 1960s.
What was new
What was new about the CK722 was not its technology but its origin. The CK722 museum calls it the first low-cost junction transistor available to the general public, and the Transistor Museum the first $1.00 transistor, in 1956. Technically it was the same device as the CK718 hearing-aid transistor, only out of specification: Industrial Alchemy writes that units from Raytheon's early production which did not meet the advertised specifications were sold under a new number as low-performance devices specifically for the hobby market. The Transistor Museum notes that the blue and silver cases in fact contain a complete small hearing-aid transistor. The worthless part of the output thus became the best-selling part; per IEEE Spectrum, Norman Krim saw an opportunity instead of discarding thousands of them.
What the sources leave open: Two accounts by the same author in IEEE Spectrum differ on the type chain: in 2003, rejected CK718s were relabelled CK721 or CK722; in 2011, the batches were labelled CK721 and then released as CK722. The quantities also conflict: Spectrum gives tens of thousands between 1953 and the mid-1960s, the CK722 museum hundreds of thousands. Ratings appear only in the table of the advertisement; per RF Cafe, collector voltage maxed out at around 8 volts.