Another Sound Lens, 1926

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One hundred years ago this month, the June 1926 issue of Science and Invention showed this simple science project, that’s probably good for a blue ribbon today at the science fair. Just as a lens made out of glass can refract light waves, a lens made of gas can refract sound waves. If this project looks familiar, it’s because we previously showed another version.

The 1926 version calls for the balloon to be filled with “carbonic acid gas.”  But since carbonic acid is unstable, it immediately turns into CO2 and water, so the balloon is just carbon dioxide.  You should be able to fill the balloon using vinegar and baking soda.  For those who want to experience more danger, you can look at the 1927 version.  If you need step-by-step instructions, you can find them at this site.



Selling School Sound Systems: 1951

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Seventy-five years ago, the June 1951 issue of Radio Retailing gave dealers some pointers on selling sound systems to schools. It focused on the case study of a North Carolina dealer who successfully secured the contract for a new high school being built in his town. This dealer prepared carefully and presented detailed information to the school board leading up to the award of the bid. By the time it came to make the selection, that dealer was viewed as the expert, and he got the contract, despite another bid coming in slightly below his.

In making the original presentation, he included features that he thought might be of interest to the school. His philosophy was that features could be removed if the price tag were too high. But once he planted the seed, the board opted to take most of his suggestions.



1956 Motorola Pager

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Shown here, 70 years ago in the June 1956 issue of Radio Electronics is the Handi-Talkie pager from Motorola. It was billed as “low frequency,” which presumably means the 30-50 MHz band, and used a vibrating reed, matching a corresponding one in the transmitter. It weighed in at only 10 ounces and was powered by a 4-volt mercury battery.



1941 BBC War Reporter

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Eighty-five years ago this month, the June 1941 issue of Radio Craft had this cover image of BBC broadcaster Robin Duff broadcasting a live eyewitness account of a London bombing, while the fires were still burning.

The magazine noted that radio broadcasting was a valuable communications
link between the government and the people.



1926 Mobile Telephone

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One hundred years ago, the Weimar Republic was at its peak, although four years earlier, the New York Times had first reported the potential danger from a popular idol with the capacity of swaying crowds to his will. But this German citizen is making use of the latest in technology, namely, being able to make or receive a phone call from a moving train, and the June 1946 issue of Radio News detailed the system in use by the German railroads.

The phone relied upon a carrier current hookup. There was an antenna on the rail car, and the signal was carried by the telegraph wires that ran along the track. An operator at the station connected calls to the wired phone system, and calls could be placed anywhere with long distance service.

 



Television 1946

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Eighty years ago, there were about 10,000 families in the United States with television, but it was rapidly growing. They would soon be guaranteed four hours per day of programming, as the FCC was about to adopt rules conditioning licenses on providing 28 hours per week.

The June 1946 issue of Popular Science reported on the state of television in the United States, and the cover picture showed the transmitting towers of WNBT atop the Empire State Building. Thirty feet had been added to the building, and with gain antennas, the station boasted a range of 60-70 miles. The next big event was said to be the Louis-Conn fight on June 19, which was to be telecast.



1966 Kit Building

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Sixty years ago, some would have considered soldering to be a “macho” activity. This gentlemen, however, shown in the June 1066 issue of Radio-TV Experimenter, was more progressive, and he realized that Gladys probably had better eye-hand coordination than he did (especially considering those beer cans on the table in front of him). I suspect that as soon as the kit was complete, it worked flawlessly.



Universal Volume Control Kit, 1941

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I don’t envy the poor radio serviceman shown in the left illustration, in the June 1941 issue of Radio Retailing.  That customer doesn’t look very happy. If the poor guy got drafted the next year, the drill sergeant couldn’t scare him any more than she did. She was going to miss her favorite programs for a few days, and it looks like she’s taking her wrath out on him.

But the customer on the right is happy. She would be able to listen to her programs immediately. The difference was that the dealer on the right stocked a kit from the International Resistance Company, 401 N. Broad Street, Philadelphia.



1956 4-Transistor Radio

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If you wanted to be the first on your block to have a transistor radio seventy years ago, one good way to meet that goal would be to build the one described in the May 1956 issue of Popular Electronics.  It was said to pull in local stations with loudspeaker volume with no external antenna.  It consisted basically of a crystal set followed by four stages of audio amplification.

Crystal sets often have very wide tuning, due to the detector loading down the tuned circuit and reducing the Q factor.  In this case, however, the coil is tapped to reduce this effect.