Nuts and Volts - September 2013

by Bryan Bergeron, Editor by Bryan Bergeron, Editor

DEVELOPING

Nostalgia and the Amnesia of Time

I make a habit of attending the MIT flea market, held in Cambridge once a month in the summer and fall. I always find what I’m looking for: feelings of nostalgia. There’s inevitably someone selling a HeathKit transmitter, a Simpson multimeter, an analog Tektronix o’scope, or some other equipment like the ones I either used to own or longed for. Now, I can afford to buy just about anything at the market, but I don’t have the time to devote to refurbishing something that went out of production a few decades ago.

Life was certainly simpler when a receiver contained just a pair of transistors or (like a CW transmitter) only a single tube. Electronics were certainly more rugged when everything was built on a steel or copper chassis, but not necessarily better. Take the flash bulbs in the accompanying photo, for example.

The bulb in the foreground — about the size of a refrigerator bulb — is all set for ignition. The one in the background is recently fired. Both are built like tanks. Prior to igniting the bulb with a 6V battery, I dropped it onto a hardwood floor from about three feet. It just bounced.

Trouble is, now I have to dispose of that bulb. Who knows what heavy metals are on the other side of the glass? Like those old receivers and transmitters built on a steel chassis, indestructible isn’t always a good design goal.

While I sometimes long for the simpler days when perhaps two dozen discrete components could be used to create just about anything, I also remind myself that there were real limits to what could be accomplished. A tube-type guitar amp was certainly easier to fix than a modern solid-state amp, but there were few — if any — onboard special effects. Plus, replacing the output tubes every three or four months was expensive.

I think that time has smoothed the rough edges of the older electronics technologies. Point-to-point wiring was fun, easy to trace, and allowed the components to cool by airflow. There was little that could be done for miniaturization, however. Some innovations are just cool because they provided a glimpse of things to come. Take the first Motorola walkie-talkies. These payphone-sized devices paved the evolutionary path to modern cell phones.

Nostalgia aside, is there any practical value in reexamining the electronics of yesteryear? Of course. There are lessons to be learned about layout, construction, For example, modern high-end tube amp manufacturers avoid ordinary audio-grade electrolytic capacitors in favor of sealed, computer-grade capacitors that have life expectancies of 100+ years. If you’ve ever refurbished a tube-type audio amp, you know that the electrolytic capacitors are the first components to go.

We’ll continue to feature nostalgic circuit projects in Nuts & Volts. Even if the electronics discussed predate your parents, I think you’ll find them worth reading. Some of the lost arts are worth remembering. NV