Transistor Museum Oral History Ralph Greenburg "The Early Years" Page 3

EARLY TRANSISTOR HISTORY AT MOTOROLA

“THE EARLY YEARS”

By Ralph Greenburg

In a way it was good that all of us in the lab had had only limited prior knowledge of transistors. We had no pre-conceived notions of their behavior and so we learned by doing. One time Paul Galvin stopped by and noticed some strange sketches one of the engineers had on his desk. These were drawings of a bunch of transistors connected together in all sorts of configurations, he had probably invented the Darlington connection before Darlington did. Paul asked him what was the purpose of all this and he replied he was trying to see if any of the connections would give better performance or higher input resistance or whatever. Paul congratulated him and said keep investigating all new aspects as that is good research. Wise words from a wise man.

By July 1954 we had pretty much exhausted the analysis of the XN-1 but we were advised that prototype sample of a new device was coming soon. A Phd, one William Taylor, had been hired and his expertise was large junction transistors that he had developed at the University of Nebraska. Seems that the auto radio group in Chicago badly wanted a power transistor for the out put of a radical different radio. They wanted to get rid of the unreliable vibrator power supplies and run everything of 12 volts since they knew the auto companies were going to switch from 6-volt batteries to 12 volts. They knew Tung-Sol and one vacuum tube company had developed a line of tubes that worked well at 12volts in all sockets except the power output stage. And if a practical power transistor could be developed they could switch production to a hybrid radio without the bothersome vibrator.

Myself and another engineer were appointed to check out the power transistors. Our first project was to find a low voltage high current power supply. Nobody seemed to sell them. The closest was 6-volt battery chargers. So we bought a charger and 4 6-volt car batteries. The batteries were hooked up in series and tapped at every 2vot cell. So know we could test the devices from 2-24 volts and up to several amps. We were soon supplied with some crude stud mounted devices with a dome shaped copper top that hat two flying leads coming out of the top connected to the base and emitter. And now the fun began as we had to learn about thermal resistance and heat sink methodology. One other thing the engineers in Chicago wanted the devices sorted by power gain not current gain. At first we would apply a low frequency signal into the base then measure the input current and voltage as well as the output voltage across a given load resistor. What was needed was a power gain tester and my boss assigned me the task. Circuit design is not my strength but with doing some research and with help from my boss I succeeded.

Go To Greenburg “The Early Years”, Page 4

A Transistor Museum™ History of Transistors Publication

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