Elmer Wolff Jr


Oral History – Elmer Wolff Jr (Continued)


To act as an industry “pump priming” function for the expanded use of transistors, TI added some applications engineers to the Semiconductor team.  At first, this applications group consisted of two people – Jim Nygaard and Ed Millis (if my memory is correct).  TI had to develop the application, take it to a potential customer, and work with the customer’s engineers to explain the circuits and how to use the devices. 


In the early manufacturing stages, we did not have enough production controls to produce all the transistors with the same electrical characteristics, such as noise levels low enough to become the input device in a hearing aid amplifier.  As a result, we had to select devices from a manufactured batch that met a combination of gain and low noise sufficient to support the hearing aid business.  We used a color code to identify the performance level of specific devices.  Can you imagine using colored paint (yellow, green and red) to identify transistors that could be used to make a complete set for a hearing aid?  Well, that’s how we did it in the beginning, and we didn’t think it was such a bad idea at the time. 


All of the engineering types at TI back then built circuits, like amplifiers and oscillators, using these early transistors, and they kept these things in their desks and would do experiments on this stuff.  I suspect that Mark Shepherd knew all about this, and I think that some of these experiments ended up on Pat Haggerty’s desk.




Oral History – Elmer Wolff Jr (Continued)



This photo shows the chassis from a Sonotone Model 1111 hearing aid.  The circuit uses three TI type 203 germanium grown junction transistors – two have been removed from the chassis and are shown at the bottom of the photo.  Note the type number “203” with a date code of 401 (1954, week 1).  Note also the reverse side showing the TI State of Texas Outline trademark. The 203 transistor remaining in the chassis can be seen in the lower right, with the three leads mounted in a white base.  Note also the swatch of light blue paint on this transistor!  This is the technique described by Elmer Wolff that was used to indicate specific performance levels of these early transistors.  Elmer was the development engineer responsible for the manufacturing of these transistors.


Wolff Oral History, Page 5


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