Historic Transistor Photo Gallery

Photo Essay – Bell Labs M1752 





Photo Essay Commentary

According to the Transistor Data Sheets appendix of the lecture material for the Sept 17-21, 1951  Bell Telephone Labs Transistor Symposium at Murray Hill NJ, “A limited number of development models of the BTL M1752 have been made for preliminary study…”.  The figure shown above left is a section of the M1752 dimensional drawing from that data sheet.  By 1952, the M1752 developmental work had progressed sufficiently to allow production of the junction transistor by Western Electric in quantities needed by the military and for production phone equipment.  The “Fifth Quarterly Progress Report, 1 May 1952 to 31 July 1952, for Transistors” produced by BTL to document progress on transistor development provides an excellent model number chart (shown in the lower right photo).  Note the cross reference of three types of M1752s to 2N27, 2N28 and 2N29 model numbers, used for actual production.  Examples are shown in the top photo - 2N27 with color code, and stamped 2N28 and 2N29.  These metal cased units (all from the mid 1950s) are still functional.  



Copyright © 2004 by Jack Ward. All Rights Reserved.