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TRANSISTOR
MUSEUM™ Historic Transistor Photo
Gallery |
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HISTORIC
NOTES The
first transistors developed at Bell Labs were point contact devices, and the
case style for these early transistors (known as the Type A transistor) was a
metal cartridge [1]. The metal cartridge style evolved and
continued to be used for Bell Labs and Western Electric point contact
transistor development through the mid 1950s. An additional case style for point contact transistors was
developed at Bell Labs in the early 1950s – the case was fabricated as a
small plastic bead, with the point contact junctions completely encapsulated
in the plastic (see photo above).
This transistor type, known as bead type point contact, was the basis
for several production devices at Western Electric, including the 2N23. Both case styles (cartridge and bead)
were used only until the mid 1950s, when an industry standard Jetec style
case was developed [4]. Within a few years, the point contact
transistor technology had been superceded by junction transistor technology,
and point contact production ceased (except for a few replacement units
manufactured by Western Electric as a late as the mid 1960s). |
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Copyright © 2004 by Jack Ward. All Rights Reserved. http://www.transistormuseum.com/ PAGE 1 |
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