Bernard N. Slade


Oral History – Bob Slade


Experimenting with a TA165



Although existing TA165 transistors were constructed over five decades ago, and represent the earliest type of transistor technology (point contact), it is possible to coax demonstrable transistor action from some of these “workhorses”.   The circuit above is a classic, and will oscillate only with a point contact device  - this is because point contact transistors exhibit a unique property known as “negative resistance”.  It is this feature that allowed the first transistors to be better suited as oscillators, not linear amplifiers.  With the capacitor “C” selected at .1 to .25 MF, the circuit will produce an audio tone. Not all TA165s are still functional, as the epoxy case material has likely allowed moisture penetration and resultant degradation of the internal germanium junctions.  You’ll find a recent 10 second sample of audio produced by an active TA165, connected as above, in this mp3 file:


TA165 Audio Sample


The fact that a remaining 55 year-old TA165 could produce this audio sample is a real tribute to the pioneering work done at RCA in the early 1950s by Bob and his team in the Semiconductor Advanced Development Group – quite an accomplishment for RCA’s first transistor engineer.





These Audio Links are Excerpts

from a 2005 Interview with

Bob Slade.



Starting at RCA’s Tube Division on the Same Day as the Public Announcement of the Invention of the Transistor 

Bob Slade Audio Clip #1




Tools and Processes Needed to Build the First RCA Point Contact Developmental Transistors

Bob Slade Audio Clip #2




Types of Research to Better Understand Point Contact Transistors

Bob Slade Audio Clip #3




Early Alloy Junction

 Germanium Power Transistors

Bob Slade Audio Clip #4




Recollections by a Young Engineer about the Early Transistor Program at RCA

Bob Slade Audio Clip #5







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