A SURVEY OF EARLY POWER TRANSISTORS

by Joe A. Knight

PACIFIC SEMICONDUCTORS INC 1960s SILICON

POWER TRANSISTORS   

 

 

 

ABOVE, L-to-R:  The first item is the PSI  in-house numbered "PT900", first released in late 1960.  It was the first of the new 125-watt NPN Triple-Diffused Silicon Mesa Power Transistor series which were numbered from "PT900 to PT920".  These enclosures were over one inch in diameter.  The cut-open middle device shows the substantial size of the square junction-element (between the wire leads) that was necessary to achieving this large amount of power dissipation.  (This PSI series used the same style enclosure as the new Westinghouse 2N1015/1016 series 150-watt silicon alloy Power Transistors, which came out in 1958, also developed through an Air Force contract. See the chapter on Westinghouse Power Transistors.)  In 1961 PSI released variations of their new silicon output devices as JEDEC registered versions, listed as the "2N1899 (shown far right) -  2N1904" types.

 

Note:  In 1963 PSI stopped painting their devices black as did many other manufacturers just about that same time.  Heat dissipation showed no justifiable difference due to the extra cost of an external color application - not as newer designs became more and more efficient and as unit costs were driven ever lower.

 

 

 

 

 

Go To PSI Early Power Transistors, Page 3

 

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Joe A. Knight Early Power Transistor History – PACIFIC SEMICONDUCTORS INC  Page 2