by Joe Knight




Minneapolis-Honeywell was a major supplier of control systems for buildings, airplanes and such, and foresaw early-on the need for semiconductor devices they could use in these high-tech environments.  Consequently, they embarked sometime in early 1953 onto producing a high current power transistor that could work within their large mechanical and electrical control systems.  By late 1953 they had announced they were in production with their own 20 watt transistor for use in their aircraft fuel-gauge systems.  This product seemed way ahead of what anyone else was doing at the time.  However, no Honeywell commercial transistors were available at that time - these devices were only made for in-house product use.  (Note: All these transistors were manufactured by the Semiconductor Products Division of the Minneapolis-Honeywell Regulator Company, and are being referred to as “Honeywell” transistors.)


TOP ROW, L-TO-R:   The first two items are identical to those announced by Honeywell in late 1953 ('Electronics' article, December, 1953) as their first 20 watt (dissipation) power transistor.  As these both have stamped control numbers on them they are likely in-house usage types from 1953/1954.  The middle item is the first Honeywell transistor commercial product, the 2N57, available in early 1954.  It was advertised as a true 20 watt dissipation device and is the same diameter as the first item, it's likely predecessor.  (All types shown in this picture have the respective connections stamped into the top surface:  "B, C and E".)  By early 1955 Honeywell released a series of power transistors which did not have RETMA registrations but were variants on and the same size as the 2N57 and were called the H-1 thru the H-4.  The H-1 and H-2 (fourth item) were rated at 20 watts dissipation.  The H-3 and H-4 (far right item) were rated at 5 watts dissipation.  Lastly, an even higher power device called the "P-11" (not shown), rated at 60 watts dissipation, was released in 1954/1955 and looked like an even larger version of the first two 20 watt items with the flared bottom skirt.   All these Honeywell devices were Germanium PNP types and all have the typical threaded bolt on the bottom face for surface conduction of the excess thermal energy into a larger heat sink. This greatly affected their dissipation rating.


BOTTOM ROW, L-TO-R:   By early 1956, Honeywell announced another series of power transistors called the H-5, H-6 and H-7 (first three items above).  These had the new stepped outer housing with solder connecting pins as opposed to the wire leads of the top row items.  These were all alloyed junction PNP Germanium types.  In late 1957/early 1958 Honeywell released the equivalent RETMA types, the 2N538, the 2N539 (fourth item) and the 2N540, far right.  These were all rated at 10 watts dissipation by Honeywell who was getting seemingly more conservative with their output ratings.   (There seems to be no evidence of an H-8 or a H-9 device ever made.)

Go To Honeywell Early Power Transistors, Page 2

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Joe Knight Early Power Transistor History – HONEYWELL