My First Transistor Radio- A Disruptive Techno-Social Experience


A recent trip to a high school science fair brings back memories of my own efforts to master science as a child working in my basement. There was very little in the way of adult guidance but we learned how to build things from library books and we had no real restraints on utilizing toxic chemicals, ionizing radiation, or dangerously high voltages. My friends would collect items at large and convene on Saturdays to conduct experiments. At the age of ten, I had learned to wield a soldering gun and could connect a circuit using only a schematic diagram.


My most memorable project was a single transistor radio. I used what at the time was one of the first affordable transistors available to the public- the Raytheon CK722, introduced in 1953. What made this project so memorable was the effect that it had on many of the adults that I engaged to “try it out”.

The world worked on vacuum tubes at that time and radios were bulky and power hungry devices that gave off heat and made various extracurricular noises ranging from power line hum to whistling and squealing. Television had just become affordable and those living in fringe areas often saw a picture only dimly through what looked like a snowstorm but was actually the random noise that covers a weak broadcast signal.


My circuit was simple and had no special technical merit. It consisted in today's vernacular of a diode detection stage followed by a single transistor amplifier. The audio signal was output to high impedance headphones and was powered by a single penlight battery. When installed in a small clear plastic box, it did not look like an electronic device. There were only six parts! What it did, however, was amazing. Hooking an alligator clip to a radiator or a window blind made the earphones come alive with a seeming universe of broadcast stations.


The radio performed at a comfortable volume and demanded no appreciable power consumption. My grandfather, an electrical contractor who had serviced radios of the 1920-1940 era, was dumbfounded and spent considerable time studying the circuit. To him that little transistor was a total conundrum and challenged everything he knew about vacuum tube technology. He knew, of course, about crystal sets[1], but they did not provide the performance of the six-component wonder. He did later master the transistor but he often commented to others that my radio had been a disruptive moment for him.


Other adults with less knowledge of radio receivers simply wanted one and after several more years they were able to buy sophisticated transistor radios that were available on a scale of variety and low cost that was unanticipated by the manufacturers of the now obsolescent vacuum tube radios.

My later education included both technologies, and I sometimes worked with the vacuum tubes that lingered in the stereo systems and TV sets through the 1970's. In the 1980's I met the vacuum tube again unexpectedly. I was with a team restoring a 1950's era USAF aircraft at Aberdeen Proving Ground here in MD. As we powered up the electrical system for the first time, everyone was on the interphone system to monitor all compartments of the aircraft for signs of possible short circuits. After the master switch was activated, silence reigned on the intercom for about 30 seconds after which the test leader shouted that something was wrong. I suggested that he wait. Several seconds later, the sounds of a bank of vacuum tubes warming up to their task was heard in everyone's headset. I was one of the few participants who recognized those sounds as validation, that after 20 years of neglect, the tubes and their electrical circuits were ready to serve another tour. And they did.

Today, the unit transistor is almost gone. It has faded and the integrated circuit and its new surface mount derivatives rule supreme. Someone in the oscilloscope repair business said in a brochure published last year that if your device was made after 1997, it could not be serviced economically. What he seems to be saying to me is that there is no longer a market for the skills involved in reading an electrical wiring diagram or using a soldering iron.


[1] An authentic crystal set used an actual fragment of galena crystal as a detector. A small bronze wire called a cat's whisker was used to probe for sensitive spots on the crystal's surface that would activate its function as a radio frequency detector. The opportunity to experience the thrill and satisfaction of manually operating a crystal radio is sadly absent from most of today's school science experiments. See the real thing! )