A SURVEY OF EARLY POWER TRANSISTORS

by Joe Knight

GE 1950s SILICON POWER TRANSISTORS

By the mid-1950's the General Electric Company had for over 40 years been a power-house of vacuum tube development and production. GE, along with RCA, AT&T and Westinghouse, controlled most of the patent rights to the world of thermionic emissions as we knew it then. GE would become no less a leader in semiconductor development, having launched their own transistor research program soon after Bell Labs announced the invention of the transistor in 1948. Their wide product development and market penetration in semiconductors was second to none by the late 1950's.  After the war GE had been one of the first companies to produce germanium rectifiers and so were well prepared to take this next step in solid-state electronics when the transistor came along.

 

Their early lead in rectifier production would provide them with a sizable market share of that product field for many years to come.  Additionally, in 1958 they found great success with their new Silicon Controlled Rectifier (SCR) devices (see the Oral History Chapter on GE's F.W. Gutzwiller). The one product area where the competition seemed to have left GE in the dust was in Power Transistors.  GE had not attempted any commercial in-roads into the growing Germanium TO-3 (or other) type of high power output products, seemingly leaving the competition to fight it out, intentionally or not.  By 1957, higher output Silicon Power Transistors were beginning to surface from such companies as T.I. and Transitron.  Perhaps feeling the time was finally right, GE ventured forth with the development of their own Silicon Power Transistors.     

 

 

Go To GE Early Power Transistors, Page 2

 

 

This new technology was first shown in an early 1956 GE advertising flyer (see scan at left) promoting the greater power dissipation characteristics of "Silicon Power Transistors" over the larger Germanium types.  While supposedly capable of operating at up to 85 degrees C (185 F) with a moderate 8 watts of dissipation, this was not a very realistic parameter for designers to work with, as other components in the circuit likely would have expired by then. The first image of this new GE output device shows a rather unique round flat basing design, using three straight connecting pins (not the usual two pins then currently used for power transistors) and a threaded stud heat-sink attachment, not too unlike some of the early W.E. power transistors of 1955/56. It should also be noted the wide variety of other silicon devices that GE was also developing at that time. The bottom row "Silicon Double Base Diode" would go on to become the GE "Unijunction" product line.  Plus, their line of silicon rectifiers was really taking shape by 1956.  

 

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Joe Knight Early Power Transistor History – GENERAL ELECTRIC