EARLY TRANSISTOR AND DIODE HISTORY

AT BELL LABS

Art Uhlir Jr.

Oral History – (Continued)
NOTE: The BTL Type-A transistor (second from left) was provided by the Hosking Collection.
	These photos illustrate the various types of transistors available to Art Uhlir Jr. during his work at BTL in the early 1950s. The three rightmost units in the top photo are all plastic cased, which, according to Art, was a primary directive from Jack Morton, the manager of the Transistor Development Group. The two white plastic units on the right are germanium point contact devices (a 1N105 diode and a 2N23 transistor). This packaging style was known as “bead type”. The black plastic unit in the center of the top photo is an M1752 germanium grown junction transistor – this is an historic device from 1951/52 and represents the earliest type of junction transistor. The two metal cased units to the left in the top photo are germanium point contact transistors. The 2N67 is a production device made by Western Electric in 1956 and represents the “state of the art” in the short-lived point contact transistor technology. Next to the 2N67 in the top photo is a very early experimental “Type A” BTL point contact transistor – it is a pre-production device, hand labeled “AM1412”. The photos to the left are from the Sept/Oct 1954 WE magazine and illustrate some details of the assembly process required to build grown junction transistors. Art mentions in his Oral History that his first assignment was to perform life tests on point contact transistors (likely on units similar to the AM-1412) and then he moved on to characterizing the grown junction transistor “floating potential problem”. He used units mounted on headers (as shown to the left) which were not yet encapsulated in plastic or metal. ______________ Go To Uhlir Oral History, Page 6
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