An Interview with F.W. “Bill” Gutzwiller

 The Early History of the Silicon Controlled Rectifier


Oral History – Bill Gutzwiller (Continued)


After you had become involved with the germanium power rectifier program, what events led to the development of the silicon controlled rectifier?

Quite quickly I found myself the application engineer for all of Clyde’s rectifier products in addition to the 5 amp germanium rectifier.  I was called on to give lectures on rectifier products and their uses in marketing seminars for customers and in training sessions for the field sales force.  I soon was out-of-town at least once a week and I was driving the Thruway to Syracuse, Schenectady, or Rochester almost every day.  Among the field sales people and their customers, I was being increasingly looked at as “Mr. GE Rectifier”.  This amused my father back in Milwaukee, since he was looked at as “Mr. Allis-Chalmers Rectifier” because of his expertise in the application of mercury-arc rectifiers.  Germanium and the even newer silicon diodes were promising to soon relegate mercury-arc to the scrap pile because of lower costs, higher efficiency, and longer life.  Even Allis-Chalmers was buying our new products.


Because of my earlier work on industrial control systems at Schindler, Cutler-Hammer, and Harnischfeger, I was continually looking to our physicists and engineers for some way for the developing semiconductor technology to produce what to me would be the “holy grail”: a controllable rectifier. 




Oral History – Bill Gutzwiller (Continued)


This would be a rectifier that would not only convert A-C power to D-C power, but would also control the amount of power from zero to maximum steplessly and efficiently.  This would be the solid-state equivalent of the gas thyratron, the motor-generator set, and the grid-controlled mercury-arc rectifier tube.  Besides replacing all these devices, a “Silicon Controlled Rectifier”, as I coined the term, would open up untold new areas of applications in industrial, military, and consumer markets. 


I talked up the “SCR” to the point where our advanced engineering people started looking for ways to achieve such a power device.  When scientists at Bell Laboratories published a paper on a PNPN signal diode device*, Gordon Hall and other physicists in Clyde recognized that it exhibited characteristics that might achieve what I was pushing them for.  Gordon and his technicians started playing with various semiconductor processes.  In short order they produced a power version of the PNPN diode, but with a third lead to control the point in each A-C cycle when the device would switch on.  It was the exact functional equivalent of the gas thyratron tube except without its big glass envelop and its glowing red filaments and attendant power losses. 


Go To Gutzwiller Oral History, Page 6


* Reference seminal Bell Labs paper by Moll, Tanenbaum, Goldey and Holonyak, “p-n-p-n Transistor Switches”, Proc. IRE, Vol. 44, September, 1956.


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