Jerry Suran – The Story of the Unijunction Transistor 



Oral History – Jerry Suran (Continued)


Remember these germanium transistors in those days, the experimental ones that we were building in the laboratory, were put in a little vial, a tiny test tube filled with silicone oil to stabilize the surface.  Then it was sealed with a wax seal on the input where the wires came into the transistor.  The wax seal was just to stabilize the wires.   So, we were experimenting with devices that were built that way, and I guess a collector lead had broken off, and in a place we couldn’t see it. 


So, at this point, with the collector lead broken, then the two remaining ohmic contacts, along with the remaining emitter lead, start to look like a unijunction transistor.  Is that right?


That’s how we got the name, “double base diode”.  When you measure the dc characteristics of the input, when you tie the two bases together, it was just like a diode, but when you put a field across the two base contacts, this thing oscillated, and it was oscillating with the parasitic capacitance of our instrumentation on the input side. 


So, we were quickly then able to determine that we had a device that was very different from what we expected, and it was a serendipity effect because the collector contact had opened up quite unexpectedly – as far as I can recall, that was how the unijunction transistor was discovered.



Go To Suran Oral History, Page 4




Oral History – Jerry Suran (Continued)




This is a photo, reproduced from Electronics  (Feb 19, 1968), showing a sample of one of the  original double base diodes, made by Arnie Lesk in John Saby’s lab in 1953 and provided to Jerry Suran for device characterization and circuit development.  These early unijunction prototypes were quite fragile, with a cork base (painted red in this photo) and an inverted glass vial, filled with silicone oil, used to protect the germanium die.



COPYRIGHT © 2005 by Jack Ward.  All Rights Reserved.  http://www.transistormuseum.com/