1938 Four Tube Portable

1938DecPM11938DecPM2The young men in this picture would, in just a few years, be on their way overseas to fight the Germans and the Japanese, but in 1938, they were relaxing outside, and enjoying a radio broadcast thanks to the four-tube superheterodyne receiver described in the December 1938 issue of Popular Mechanics.

The magazine pointed out that many earlier so-called portables weren’t very portable at all, due to their size. But this one weighed in at only ten pounds, including batteries. The performance was said to be above average, and the drain on the battery was low. It drew only 8 mA from the 90 volt B battery, and 300 mA from the A battery.

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1943 Root Cellars

Screenshot 2023-11-28 9.15.20 AMScreenshot 2023-11-28 9.17.36 AMEighty years ago, many Americans were enjoying plentiful meals without worrying about rationing points, thanks to their victory gardens. And the December 6, 1943, issue of Life magazine offered some pointers about how to store the bounty of those gardens for the winter. Above is an image of a well-appointed root cellar. The magazine noted that a well-ventilated corner of the cellar, where the temperature remained between 35 and 50 degrees was ideal. And some of those fruits and vegetables are put up in some of the four billion Mason jars that were currently in use in the country.

For those without a cellar, the magazine offered some ideas such as the one shown at the left for storage of root vegetables. In this one, a barrel is buried in the yard. After filling, it’s covered with straw, and then soil. On nice days during the winter, it is opened, and food for the next two or three weeks is removed.



California Ramblers, 1923

Screenshot 2023-11-28 11.34.58 AMA hundred years ago tonight on the radio, you could listen to the California Ramblers performing over WEAF, New York.  But it wasn’t just any broadcast, as seen from the clipping above, from the January 1923 issue of Talking Machine World.  Due to the radio. Columbia records noted that the lid of many a long forgotten phonograph had been frozen.  They fought back with radio, and purchased time on WEAF every Tuesday and Thursday at 9:15.  Each broadcast featured a Columbia recording artist, and was broadcast right from the recording studio.  If people liked what they heard, they could buy a record, enabling them to listen to it whenever they liked.

According to Columbia, listeners around the country had tuned in.  The group is shown here, in 1931, in the June 1931 issue of What’s On The Air.  You can hear them in their 1925 recording of “Five Foot Two Eyes of Blue”, below.

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Science Fair Project: Drop of Water Evaporating on Red-Hot Metal

1938SepPSIf Junior has a science fair project that’s due soon, and he or she likes playing with fire, then this simple project form 85 years ago is just the thing to take home the blue ribbon.

Like any good science fair project, this one answers a question, namely, “will a drop of water evaporate faster on a red-hot piece of metal, or on one that is only moderately hot?” The classmates, and probably the teacher, will undoubtedly place their bets on the one that’s red hot, but Junior will prove them wrong.

The reason is that on the red hot surface, a cushion of steam forms, and the drop of water mostly retains its shape as it dances about. But if the surface is only moderately hot, the water spreads out and evaporates immediately.

Most schools have probably turned off the gas to the bunsen burners in the science lab, but you can bring your own from home. You can get this handy propane bunsen burner from Amazon.  In fact, the science teacher will probably be a little bit jealous and want to get one for themself.  The school probably has the lab stand, but if not, you can also get that on Amazon.

This project appeared in the December 1938 issue of Popular Science.



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1923 Photo Finish

1923NovSciInv2The concept of a “photo finish” has been around for a century, as shown by this Illustration in the November, 1923, issue of Science and Invention.

This setup was in place at the Maisons-Laffitte Racecourse near Paris. The horses crossing the finish line broke a thread, which would trip the shutter of the cameras above. The photos would be ready in four minutes to decide a close race.



Catalina Island Telephone Link: 1923

1923NovPSWe previously reported the construction, in 1921, of a radiotelephone link between California and  Santa Catalina Island, 26 miles across the sea (40 kilometers, for those in leaky old boats).  That link was in use for only two years, as reported here in the November 1923 issue of Popular Science.

In 1923, a cable was installed for both telegraph and telephone connections, both of which were multiplexed to allow multiple conversations.  One advantage of the new system, alluded to in the original article, was that radio conversations could be listened in to.  While some scrambling was put in place, the signals were transmitted over the air.  In addition, the radio license was surrendered, and that wavelength made available for broadcasting.



Homemade Photocell

1948NovPracWirToday, we have another science fair project suitable for students who like to use dangerous chemicals. It’s a homemade photoelectric cell. It won’t provide large amounts of current, but it is measurable, and it can probably be used to receive a signal from a modulated beam of light, simply by connecting it to an audio amplifier (similar to this previous project).

The cell consists of a beaker of water in which a “pinch” of salt has been added. Into this are inserted strips made of copper and lead. The copper is heated with a torch to oxidize it, after which it is scrubbed with nitric acid. There is some current even in darkness, but when the copper strip is exposed to light, the current increases.

The project appeared in the November 1948 issue of Practical Wireless.



1948 British Two-Tube Bedside Portable

1948NovPracWir2The plans for this two-tube British bedside portable appeared 75 years ago this month in the November 1948 issue of Practical Wireless. The set was designed to pull in the BBC Light and Home Service programs with loudspeaker volume, using commonly available components. It ran on battery power, and used two tubes. Because a small frame antenna would be used, the author realized that at least one stage of RF amplification would be necessary. Therefore, the first tube was a dual tube, servicing as RF amplifier and detector. Another tube served as AF amplifier to drive the speaker.

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Science Fair AC Generator

1963NovEIIf Junior is looking for a simple science fair project, albeit one that probably can’t be whipped together at 10:00 PM the night before it’s due, he or she can’t go wrong with this simple AC generator from the November 1963 issue of Electronics Illustrated.

The design is very straightforward. To avoid having to worry about brushes, the coil stays stationary, and the permanent magnet turns. The coil consists of 800 turns of number 28 or 30 enameled wire on a 2 or 3 inch iron bolt.

The magazine recommends using a DC ammeter, with the calibration set so that 0 is mid-scale. As the crank is turned slowly, the needle will deflect first one direction, and then the other.

Another possibility would be two LED’s in parallel, each pointing a different direction. As Junior slowly cranks the handle, the lights will alternate, and as the speed picks up, they will both appear lit.

For more projects, some of which can be whipped together at the last minute, browse our other science fair ideas.



1923 Brandeis Department Store Radio Dept.

Screenshot 2023-11-21 11.28.13 AMIf you were looking for radio supplies in Omaha a hundred years ago, the Brandeis department store was the place to go, as shown in this ad in the Omaha Bee, November 24, 1923.

You could get a complete Radiolet crystal set, normally a $10 value, for only $6.95.  That included everything you needed to start pulling in stations, since it included the headphones and antenna.

And they knew that the secret of selling radios was to get the kids campaigning for a set.  So in addition to their normal radio department on the main floor, they were to be set up in the toy department on Saturday so that the kids could make sure Santa knew the family needed a radio.