Monthly Archives: December 2022

All Aboard for a Radio Christmas: 1922

A hundred years ago, it was going to be a Radio Christmas, as shown by this advertising feature in the Washington Herald, December 18, 1922.  Various dealers had completed sets starting for $11, and one of the ads noted that Santa still had plenty of time to set up a radio.

One of the ads mentions the “Literary Digest Hookup,” which is probably the set shown here, which we previously featured.  The plans for that set appeared in the April 22, 1922, issue of the magazine, and the girls shown here were later featured for having constructed it without assistance.

The newspaper noted that December 23-30 was to be Radio Week, a time for promoting the new art and putting more sets into American homes.

 



1952 Record Player

1952DecPMSeventy years ago, these youngsters were listening to some favorite records, thanks to a new record player that Santa had just delivered. But little do the kids know that Santa had some help–Dad actually built the set, courtesy of plans found in the December 1952 issue of Popular Mechanics.

When not in use, the tone arm is placed on its holder, which actuates a switch mounted inside the cabinet, turning it off automatically. The only control for the kids to mess with was the volume control.

The amplifier used a single 3V4 tube, whose fast warmup meant that the player was ready for action the moment the tone arm was picked up. One interesting feature of the circuit is the source of the 3 volts for the filament. The set has no transformer, but the power supply for the B+ uses a selenium rectifier.  The filament voltage seems to take advantage of the rectifier’s voltage drop, as it seems to be wired across the rectifier (and in series with the phono motor and two resistors).

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1962 TV Sound Tuner

1962DecRadioElec2Sixty years ago, the December 1962 issue of Radio-Electronics showed how to make this converter to listen to TV sound in high fidelity. Of course, one way to do it would be to simply tap into the audio detector of the TV set, and feed that to the hi fi. But that, according to the article, left a lot to be desired, since it usually resulted in buzz, distortion, and background noise that would stand out like a sore thumb in a good audio system.

The solution was to build this converter, and feed it into the FM receiver. And most of the circuit was available off the shelf, in the form of the TV tuner. When these needed repiar, the local repairman typically removed them and traded it in for a rebuilt unit, making the rebuilt units readily available. Ads in the same issue of the magazine showed complete tuners for about $9.95. This tuner had a 44 MHz IF, meaning that the sound IF was 41.25 MHz.

To be able to tune this in on an FM receiver, the builder first tweaked the slugs and trimmers inside the tuner to bring it up to 44 MHz. This was fed into an amplifier-doubler, with the grid tuned to 44 MHz and the plate tuned to 88 MHz. The result was that the output showed up on 88 MHz, at the bottom of the FM dial.

With a reasonably good antenna, the little converter was said to provide good sound reception for stations up to 75 miles away.

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1947 RCA Victor

1947Dec15LifeSeventy-five years ago today, the December 15, 1947, issue of Life magazine carried this RCA Victor ad showing some of the company’s offerings for the Christmas season.

It featured first the model 63E phonograph, which featured both plenty of volume for dancing, but also fine tone for the more serious music.

The handsome model 68R3 radio tuned in both AM and FM bands, and included the ability to plug in a record player.

Finally, the model 75X11 was only 10 inches long, and the dial face and pointer glowed when the set was on, making tuning of the AM band easy. It also came as model 75X12 in ivory-finish plastic.



1922 Simplest Radio Outfit

1922DecSciInvShown here from a hundred years ago is the 7th place winner in the “Simplest Radio Outfit Contest” shown in the December 1922 issue of Science and Invention magazine.

The self-explanatory set was designed by one George Goga, who took home a $25 prize for his entry. The magazine noted that almost all of the parts, with the exception of the headphone, could be found ayt no cost in the home junk box. A pencil forms the chassis. The eraser is removed and a galena crystal inserted in its place. The coil is wound along the pencil, with about 3/16″ of the insulation cleaned off so that the slider can contact the wire.

Mr. Goga reported that he lived several miles from station KDKA, and was able to pull in concerts clearly with a 50 foot long antenna 10 feet high.



First Airplane Landing in Grand Canyon: 1922

1922DecPMIf you tried this today, the National Park Service and the FAA would probably seize your airplane and haul you off to jail. But a hundred years ago this month, the cover of the December 1922 issue of Popular Mechanics showed the first ever landing of an airplane in the Grand Canyon.

Aviator Royal D. Thomas, accompanied by photographer Anthony Ugren, successfully landed the plane at Plateau Point, despite the treacherous air currents that were known to exist there. “To the Indians who had assembled in their best paint and feathers, it must have been an awe-inspiring sight, similar to that of earlier generations of red men who saw the centaurlike cavaliers of the Spaniards and the steam train for the first time.”

The landing of the 180 horsepower plane took place on the morning of August 18. The next morning, the upward flight out of the canyon took 4-1/2 minutes, although Thomas estimated that it would have taken a minute longer if he hadn’t caught an upward air current that lifted him nearly 1500 feet.



Science Fair Ideas: Fun With a Homemade Galvanometer

1942DecPS4Eighty years ago, there was a war going on, but that didn’t stop young scientists on the home front from conducting experiments with the items available. If Junior’s science fair project is due tomorrow, he can take a cue, and whip together a great project from these ideas in the December 1942 issue of Popular Science.

Both experiments involve a galvanometer, and the magazine presupposes that young scientists know how to make one, because the instructions merely state to use “your homemade galvanometer.” But in case Junior doesn’t know, it’s easy enough. You just take a compass (a toy one from the dollar store will work just fine) and wrap a few turns of wire around it. The smallest of electric currents will cause the compass to move.  If there’s a little extra time before the science fair, we’ve previously shown how to make a deluxe galvanometer.

In the first experiment, shown above, Junior can demonstrate that water, contrary to popular opinion, is an insulator. It’s only when a little bit of salt is added to the water that it starts to conduct electricity, and the compass moves. To accentuate the effect, we recommend starting with distilled water.  And don’t worry about not being able to find the old-fashioned dry cell batteries.  These experiments will work just as well with modern alkaline D cells, especially if you purchase battery holders for them.

The second experiment, shown below, shows how to make a thermocouple. Two pieces of wire–copper and iron (or steel)–are twisted together. When the twisted wires are put into a flame of a candle, the dissimilar metals produce an electric current, as shown by a movement of the compass.  And as we always remind parents about experiments involving flames, don’t forget to give Junior a box of matches!

As with many of our projects, Junior is almost guaranteed to take home the blue ribbon, and the teacher won’t have a clue that the project was put off until the last minute.

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1937 Disco Ball

1937DecPSWhat we know as the “disco ball” has a long heritage, as shown by this depiction 85 years ago in the December 1937 issue of Popular Science. The magazine featured a number of ideas on what to do with a broken mirror, and assured readers that it needn’t signify seven years of bad luck.

1937DecPS2The magazine noted that one use was to provide spectacular color effects for parties and dances. This was done by focusing colored spotlights on a mirror-covered globe. This was made by cementing small squares of mirror on a large ball or toy globe. This was attached to a spindle which could be spun by hand or with a small geared-down motor.

According to Wikipedia, what is now known as the disco ball dates back to 1917.

If you have a piece of mirror left over after making your disco ball, you can mystify your friends with the magic trick shown below:

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1942 Miniature 2 Tube AC-DC Receiver

1942DecPS1Eighty years ago this month, the December 1942 issue of Popular Science showed how to put together this two-tube AC-DC set. The miniature set used two midget tubes, types 9001 and 9002. The 9002 pentode served as a sensitive detector, and the 9001 triode was used as a rectifier.

The filaments were wired in series, and since they required a 600 ohm dropping resistor, not one but two “curtain burner” cords were used, wired in series.

With a short antenna lying along the floor, the set could pull in local stations with good selectivity. Out in the country with a 75 foot antenna, it boasted a range of 600 miles.

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Tube Aging, 1947

1947DecRadioNewsThese workers at Hytron‘s plant in Newburyport, Mass., are aging tubes to ensure long life. An incandescent lamp is wired in series with each tube element to limit current. This process of seasoning and degasifying the tubes ensures more uniform tubes.

The photo appeared on the cover of Radio News, December 1947.