An Interview with Carl David Todd

Recollections from the First Days of Transistor Technology


Oral History Carl David Todd (Continued)


I was familiar with the 1N34 germanium diode in a ceramic case, and had dissected several of these and studied them with the microscope in the biology department at school.  I saw the similarity between the 1N34 and the transistor, and figured all I had to do was add another cat whisker, very close to the original anode.  Keep in mind that I had no micro-positioners or similar tools.  I needed a stiff wire with a very thin insulation coating.  Hey, I had seen that very thing when I broke open a 1U4 vacuum tube.  The filament was a fine wire coated with a very thin ceramic.


I tried just sliding the wire down along the other whisker, but what would hold it in place while I adjusted the supply voltages and made measurements?  Ah, yes, I had seen what had happened when a capacitor was charged up with a high voltage and suddenly discharged.  The wire would stick, being weakly spot welded by the spark.  I would just charge up the capacitor placed in shunt with the new whisker and cathode, and manually slide the ceramic along the anode whisker until it made contact and sparked.  It stuck!  I rigged up some basic test circuits and was able to see that it was working - poorly, but working!


My freshman year in college was supported by working 50 hours or more per week while taking a full load with as much overload as they would allow. My goal was to save up enough money to be able to go to Auburn, then known as Alabama Polytechnic Institute, and study Electrical Engineering.


Oral History Carl David Todd (Continued)


While at Auburn, I had the opportunity to get a job with the Auburn Research Foundation where I helped design, build, and test several computers for a top secret computer project with the Air Force. As I was wiring up all the filaments for a module, I could not help but think, "The future computers will use transistors, and they have no filaments to wire!"


I learned that Western Electric was selling some WE1698 point contact transistors to "developers" so I sent off a money order for six of them at about $30.00 each (as I remember.) They were somewhat reticent about selling their transistors to a student, but they finally relented. When they arrived, I quickly hooked them up to some special test circuits and learned that three of the six were DOA. In my experimentation, I learned just how cantankerous these devices could be. I wished for some of the new junction transistors which were more stable.


My wish was answered when Raytheon offered the CK722, so it was off to Columbus, Georgia, the closest parts distributor, where I purchased a few. Oh, these were so nice to use!





Go To Todd Oral History, Page 3





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