Then and Now

A Radio Workshop

(A transcript to parents)

Your child, along with 22 other students at Clayton Middle School, was selected to participate in a radio workshop sponsored by IBM as an extended special project in celebration of National Engineers Week (February 18-24, 2001).

The workshop was designed to teach them, through their own classroom experience, how young people make history, how a passion for learning can become exciting and rewarding, and how their ideas today can become tomorrow's inventions. As their knowledge grows, it can define their life's work, and ultimately, lead them into challenging careers that are fun.

I took a step back in time to the early 1920ís, when only a few radio broadcast stations existed. It was estimated that there were nearly 600,000 radio receiving sets in the US at that time. While this number may seem large for a technology so new, many of these were handcrafted receiving sets fashioned from readily available hardware, and assembled on old breadboards discarded by Mom. Indeed, many of those first radio receiving sets were built by the youth of that era... boys and girls alike. Fascinated by the idea of hearing voices and music without being connected by wires; they were lured into the "radio game". Many of them became "Hams" or amateur radio operators; the pioneer experimenters responsible for developing and demonstrating nearly all of what we know about radio communications today.

I attempted to create an environment simulating the experience of the youth in those early days of radio.

  1. The supplies used are easily found, readily available, and low cost.
  1. It needed to look, feel, and be "home made"... not something they can run out and buy in a store.
  1. It needed to offer a new listening experience to expand their awareness of the world around them.
  1. Like the early pioneers, it needed to appropriately challenge the technology in use.
  1. It needed to perform well, and reveal many of the important attributes of radio reception including amplification, sensitivity, conversion, tuning, selectivity, and detection. For those who are inspired, I wanted it to be capable of simple improvements and changes that the students can pursue on their own.

 

Electronic engineers always test their ideas to ensure they work before committing them to manufacturing. These proof-of-concept creations are still called "breadboards" today. The radio workshop employed this construction technique, and a design approach typical of those used in the 1920ís, as a symbolic bridge between history and the present. While experiencing the thrill of discovery enjoyed by the youthful pioneers of radio, your child also learned what itís like as a present day engineer at play.

The Breadboard

A Regenerative Shortwave Wireless Receiving Apparatus

Technologies struggle with terminology as they evolve, and the equipment used is frequently described by the tasks it performs. Before the term radio was coined, the new technology that worked without wires was simply called wireless. This term has returned to our vocabulary with computing services becoming more mobile and commonplace.

The device your child has constructed is much like the AM radio found in alarm clocks, and automobiles. It is, in every sense, a real radio receiver typical of a design that would have been found in households of the early 1920ís.

In many ways, itís very much the same:

  1. Itís a "homebrew" radio, built by its owner using supplies at hand wherever possible. The design is simple and low cost (uses few parts)
  1. The radio design employs performance enhancement concepts patented in 1912.
  1. The construction technique employed, while crude, is typical of the period.
  1. It uses a sensitive earphone rather than a loudspeaker.
  1. It is battery powered.

 

In as many a way, itís superior and quite unique:

  1. It uses transistors rather than tubes for amplification.
  1. It uses a crystal earphone that is more sensitive and efficient.
  1. It consumes thousands of times less energy. It can operate continuously on a single 1.5 volt battery for more than a month. Early radios required two batteries, with one as high as 45 volts to provide only a few hours of operation.
  1. Its relative cost is much lower. Batteries and tubes were expensive.
  1. Its size is much smaller.

In some ways itís extraordinary, and different:

  1. It operates on the shortwave broadcast bands (at frequencies of 5.8 to 7.5 Megahertz). Operation at these frequencies was uncommon, expensive, and experimental in the 1920ís.
  1. It requires only a short (6 feet) length of wire for an antenna.

Early antennas (called aerials) were often impressive wire arrays hundreds of feet long.

  1. It can be powered by a homemade battery fashioned from a fruit or vegetable. It can be modified to cover other frequencies by changing the number of turns on the coil.

While it can be perceived as a primitive and novel toy, it is in fact a dynamic tool that can lead to new discoveries, arouse curiosity, and stimulate your child's desire to learn and develop new skills. I hope he or she discovered that their achievements are limited only by their imaginations.

 

 

If you are interested in the Knightlites and Amateur Radio contact Dick at

N4HAY@arrl.net