TRANSISTOR MUSEUM™

Historic Transistor Photo Gallery   

 

Transistor Size (3/16”H X 1/8”OD)

Standard T0-18 Case

Date Code 7639 (1976 Week 39)

 

3 1/2” X 4 3/4” Military Packaging

FSCM 04713 P/N 2N705JAN 

 

MOTOROLA 2N705

 

TYPE

Germanium PNP Diffused Base Mesa

 

USAGE

High Speed Switching

 

DATE INTRODUCED

Late 1950s

 

CASE STYLES

Silver Metal

 

 AVAILABILITY

Common (High Volume Production)

HISTORIC NOTES

The first transistors were constructed from germanium and this technology dominated the 1950s.  These early germanium devices were subject to a variety of performance limitations, including temperature sensitivity and minimal switching frequency.  Nonetheless, continued improvements to germanium technology allowed the commercialization of relatively robust, high frequency transistors by the end of the decade.  The 2N705, developed by Motorola, represented one the best of these high performance germanium types, and was very successful commercially.  Harry Knowles was the R&D manager at the Motorola Semiconductor Products Division in the late 1950s and was the primary contributor the development of the 2N705 – this work is detailed in patent 3108209, filed in 1959.  At this time, most germanium transistors were either alloy or grown junction and the diffused base, mesa technique used for the 2N705 produced a dramatic improvement in high frequency performance.  This technique was based on work originally done at Bell Labs in the mid 1950s (see the Diffused Base Prototype).  The 2N705 sold in the millions of units and was used heavily by the military.

 

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