Transistor Museum Oral History George Ludwig Explorer I Satellite Transistors Page10

A Transistor Museum Interview

with Dr. George Ludwig

The First Transistors in Space - Personal Reflections by the Designer of the Cosmic Ray Instrumentation Package for the Explorer I Satellite

1958 Photo - Courtesy of JPL

Top view of pulse counting deck (scalers) used on Explorer III. Note use of the TI 2N335 series silicon transistors.

EARLY TI SILICON TRANSISTORS FOR EXPLORER I

The top scan shows the schematic for the scaler circuit designed by Dr. Ludwig for the Explorer I cosmic ray instrumentation. As described in this Oral History, TI type 2N335 silicon transistors were used. [1]. Samples of the 2N33X silicon grown junction transistors are shown above. Note the characteristic TI “Texas State Outline” stamped on top of the transistors (this can also be seen in the photo at middle left, which shows the actual scaler circuit board used in Explorer I). At bottom left are samples of the cardboard packaging used by TI in the 1950s. The date code on the 2N336 shown above is 815, which is 1958 week 15. (See [6] for a 1961 view of satellite electronics). This is the exact case style of the devices used in the Explorer I cosmic ray scaler. TI introduced the 2N33X line of silicon transistors in the mid 1950s, as an improved version of the original 900 series. The 2N33X product line sold in the millions of units (the military was a big customer) and was second-sourced by most major manufacturers, such as GE (middle unit in the photo above).

Go To Ludwig Oral History, Page 11

Texas Instruments commercial transistor packaging from the 1950s.

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