Jerry Suran – The Story of the Unijunction Transistor 



Oral History – Jerry Suran (Continued)


Up till that point, silicon could operate at higher temperatures and so could operate at higher power levels.  We switched the unijunction over to silicon from germanium primarily to increase the power.    Of course, the military was very interested in getting these devices to operate at a higher ambient temperature.


Was the military interested in unijunction transistors?


 Yes, they were.  As a matter of fact, we used one in an Apollo simulator later on to generate a very linear sawtooth wave for a TV output.  Anyway, the types of applications were just exactly what you would use a thyratron for, in the vacuum tube days.  Anything that a relaxation oscillator could do, the unijunctuion could do.  Also, with the advent of digital electronics, we thought these could be used for clocks in computers.


Eventually, the silicon controlled rectifier put it out of business, because the SCR could operate at a much higher power level.  Initially, they were used together, with the unijunction used at low power levels for triggering.  This was a combination that interested the power companies a great deal, and that is one of the reasons, I think, that GE jumped on the unijunction transistor, and became the leading manufacturer of the device.  The unijunction was big seller in those days and it made a lot of money for GE.



Oral History – Jerry Suran (Continued)


How did the original name for this device, the double base diode, change to the name “unijunction transistor”?


That’s an interesting story. For a while, we called the unijunction transistor a double base diode because that’s the way it was discovered.  We thought we had a tetrode, but in fact we had a diode with two ohmic contacts, and so it was a “double base diode”.  That was descriptive term. But the diode terminology was a misnomer because it was a three terminal device, and not a two terminal device,  and it had gain – it was an active device and not a passive device like a diode. 


I think around 1956, I was on an IRE standards committee, or actually, on the IRE circuits committee – 410, the transistor circuits subcommittee.  And most of the people on that subcommittee objected to the terminology, and were trying to standardize terminology.  We all knew that this thing was a transistor, and not a diode.  So, with pressure from the IRE, I proposed that we call it a single junction transistor, which obviously then became a “unijunction transistor”, and it was a unijunction transistor but that was also descriptive as well as correct , because a transistor was a gain device and this thing had gain.  So I think with IRE standardization pressure, we switched the name to unijunction transistor, and there was no resistance within GE or any other company to make that switch.


Go To Suran Oral History, Page 7



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