A Transistor Museum Interview with Ray Andrejasich

Recollections of Early Transistor Radio Technology

at Zenith Radio Corporation



Shown above is a mid 1970s Zenith “Circle of Sound” clock radio.  This device uses 21 plastic silicon transistors, a single clock integrated circuit and large red LEDs.  Ray worked on the design of this radio, and it was one of the last projects he worked on for Zenith.  Here are his comments: “I designed the first ‘Electronic Clock’ for our line of transistor clock radios that were using mechanical clocks.  I chose LEDs over vacuum fluorescent displays because of product life.  The clock IC was a 40 pin package from National Semiconductor.  It had separate output pins for each display segment.


Working in the midwest winter at the time, I found myself destroying our prototype clock modules by  handling them!  That's when I was first introduced to Electrostatic Discharge (ESD). 


The LED segments, the ‘Snooze’ input and the clock-settting controls were all direct wired to pins on the IC.  Won't go into details of how we protected these inputs, but we had technicians (volunteer) standing on an insulated platform, one hand placed on the top of a Van de Graaf generator and the other hand throwing bolts of ESD!


Shortly after we had our clock properly protected, the winter Consumer Electronics show came to one of the Chicago hotels.  Manufactures had individual suites for displaying their new products for distributors to place orders. Imagine the plush carpeting and low humidity heat in the suites!


I went to the show wearing my best pair of leather-soled dress shoes. When visiting the manufacturer's suites, I made sure to shuffle around before examining the displays of electronic clocks.  The casualty rate was quite high!  The positive side of my actions was that the vendors with problems had an opportunity to go back to the drawing boards before shipping product from overseas.”


Go To Andrejasich Oral History, Page 8

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