TRANSISTOR MUSEUM™ Historic Transistor Photo Gallery
Transistor Size (1/4”H X 5/16”L X 1/8”W) Date Code (Left Unit) 143 (1961 Week 43) Date Code (Right Unit) 634 (1956 Week 34) Shown at left is the 1957 model XR1, which was the first transistor radio made by Heathkit. This unit used six TI transistors: 2N238, 2N252, 2N253, 2N254, and two 2N185s.	Texas Instruments 2N172 TYPE Germanium NPN Grown Junction USAGE Converter Circuit in AM Radio DATE INTRODUCED Mid 1950s CASE STYLES Silver Metal AVAILABILITY Common (High Volume Production)
HISTORIC NOTES Although best known for introducing the first commercial silicon transistors (in 1954) and the first integrated circuits (in 1959), Texas Instruments initially entered the semiconductor market with germanium transistors, especially those designed for use in commercial AM radios.  TI’s first radio transistors were used in the famous Regency TR1, introduced in 1954 as the first all transistor radio.   Throughout the 1950s, TI was the primary supplier of these devices to many of the major transistor radio manufacturers, such as Emerson, Heathkit, Magnavox, Regency, and Zenith.  TI supplied a complete range of these transistors, suitable for all elements of radio circuitry.  For example, the 2N172 was intended for use in the converter circuitry of AM radios.  Shown above, in the top photo, are two examples of the 2N172.  The rightmost unit was used in a 1956 Emerson model 842 radio and the leftmost unit was likely sold by TI for radio repair purposes.  By the early 1960s, the type 2N172 was discontinued and replaced by the type 2N252; a 1961 TI price list shows the 2N252 available from distributors at $2.45 each.  Other TI germanium radio transistors included the 2N145 – 150 series, 2N185, 2N238, 2N252, 2N253, 2N254, 2N291, and 2N308 - 2N310.  TI manufactured germanium transistors well into the 1960s.
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