Monthly Archives: August 2020

1960 Loudspeaker Crystal Set

1960AugPE11960AugPE2Sixty years ago this month, the August 1960 issue of Popular Electronics showed how to make the holy grail of crystal sets: a crystal set capable of loudspeaker operation.

The author, Walter B. Ford, reported good reception, including loudspeaker volume on strong local stations. The set relied upon two secrets. First of all, it had two tuned circuits in the front end for maximum selectivity. It also used two 1N34A diodes in a voltage-doubling circuit. For weaker stations, headphones could be used, or it could be used as an excellent AM tuner for an external amplifier. But for the strong stations, it would drive the speaker, with no power source other than the received signal.

The ferrite loopsticks might be hard to find these days, although with a ferrite rod, you should be able to make your own.  More information can be found at this link.  More hints on sourcing the parts can be found at my crystal set parts page.

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Nagasaki

19450809Today marks the 75th anniversary of the bombing of Nagasaki on August 9, 1940.  The attack is reported here in that day’s issue of the Chicago Tribune.  If the Japanese needed further convincing to surrender, that day also brought news that the Soviets had declared war on Japan and were attacking Japanese forces in Manchuria.

The video below is a radio broadcast that day by President Truman promising that the bombings would continue until the Japanese surrendered.  The war would be over in a few days.



Light Bulbs as Dropping Resistors

1945AugPMThis photo isn’t as sinister as it looks, and nothing untoward is going to happen to the gentleman at the left. The photo is from the August 1945 issue of Popular Mechanics, and these gentlemen are dealing with wartime parts shortages. They’re doing an emergency repair on this set, and need some way to power the filaments of the six-volt tubes. The filament transformer they need is a wartime priority item, so they instead wired the filaments in series and used a 40-watt light bulb as a dropping resistor.

The picture is accompanied by a table showing the resistance of common lamps.



Science Fair Project: Moving-Coil Ammeter

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1970AugSciElecThe young man shown here is probably getting ready to collect his first Social Security check, but fifty years ago, he undoubtedly took home the blue ribbon at the 1970 Science Fair. His project was shown in the August-September 1970 issue of Science and Electronics. According to the magazine, the project would show off knowledge and understanding, but would also require dexterity with tools.

The project was a moving-coil ammeter, not unlike a commercially made meter movement. While the magazine didn’t use the moniker, this type of meter is also commonly known as a d’Arsonval meter movement, after Jacques-Arsène d’Arsonval. For less advanced students, the article referred back to construction articles for some more primitive meters, such as the hot-wire ammeter we previously profiled. Most of the meter’s mechanical parts were made of wood, so the project required some expertise in the wood shop. The form for the moving coil was made with balsa wood, whose light weight ensured a sensitive movement.

The finished product could be accurately calibrated by using a commercial VOM, a battery, and a potentiometer. Current readings were noted on the commercial meter, and then marked on the face of the homemade meter.

According to the article, if the builder used reasonable care and followed instructions, they would be assured of a good grade and congratulations from friends and teachers.  And fifty years later, there’s no reason to think the result would be any different.



Hiroshima

Today marks the 75th anniversary of the U.S. dropping the atomic bomb on Hiroshima, Japan, August 6, 1945.  At least 129,000 were killed.  The gun-type weapon (one sub-critical mass fired into another sub-critical mass) exploded 2000 feet above the city, unleashing the power equivalent to 12 to 15 thousand tons of TNT.

The Potsdam declaration, demanding unconditional surrender, had been broadcast directly to Japanese civilians over KSAI radio, and millions of leaflets had been dropped.

Preparations were underway for an invasion of the home islands, and U.S. planners estimated U.S. casualties between 130,000 and 220,000, with between 5 and 10 million Japanese deaths. Nevertheless, the Japanese leadership did not heed the Potsdam Declaration, and made preparations to continue defending against an apocalyptic invasion.

On August 14, only after the bombings of Hiroshima and Nagasaki, Hirohito addressed the nation by radio:

Moreover, the enemy now possesses a new and terrible weapon with the power to destroy many innocent lives and do incalculable damage. Should we continue to fight, not only would it result in an ultimate collapse and obliteration of the Japanese nation, but also it would lead to the total extinction of human civilization.

Such being the case, how are We to save the millions of Our subjects, or to atone Ourselves before the hallowed spirits of Our Imperial Ancestors? This is the reason why We have ordered the acceptance of the provisions of the Joint Declaration of the Powers.

 

References

 



1970 Multiband Mobile Antenna

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1970AugustPE2This month marks the 50th birthday of a pretty good idea, as evidenced by the cover story in the August 1970 issue of Popular Electronics. The article was penned by Russ Alexander, W6IEL, who was likely the originator. The article specifically addresses how to use a compact antenna from an apartment, and it makes use of Hustler mobile antennas.

The Hustler antenna is still available today, in more or less identical form. It amounts to a center loaded vertical antenna. The bottom half is a mast that attaches to the car. On top of that is a loading coil, and on top of that is a whip antenna. The loading coil and whip are tuned to a specific band. And because you need different coils and whips for different bands, the coil and whip are sold as a one-piece resonator.

So it’s fairly easy to change bands: You stop the car, get out, and swap out the resonator. But that doesn’t work very well if the antenna is mounted on the roof of your apartment building. And it doesn’t work very well if you want to change bands without getting out of the car.

1970AugustPE3So the author went to his metal shop, and made a piece which allowed him to mount up to four resonators on the same mast. For bands that are not being used, the coil acts as a trap, so the unused resonators have little impact on the transmitted signal.

The idea caught on. I first remember seeing one of these as a young ham in the 1970s in the parking lot at a hamfest on the car of prominent Minnesota ham Tod Olson, K0TO (then W0IYP). I remember thinking that it was a pretty good idea. Chances are, it originated with the magazine article shown here.

W6LENShown in these pictures W6LEN2is the mobile antenna of W6LEN, an avid WWFF activator of Southern California parks and beaches. He uses the Hustler mobile antenna on a magnetic mount on top of his minivan. While the magnetic mount is probably too small to use in motion, he has had good success with this antenna, and it takes only a few minutes to deploy when he arrives at his destination.  As with the 1970 article, he uses a homemade bracket to mount the four resonators.

Hustler eventually realized that using multiple resonators was a good idea, and they now sell the part, shown at right, so you don’t have to have your own metalworking tools. The author of the 1970 article recommended having the part plated with copper and then cadmium, after which “the finished bracket will look like a commercially marketed item.”  The 1970 Popular Electronics version had room for four resonators, whereas the commercial product has only three wings.  However, a fourth resonator can be added in the middle.



Expedient Variable Resistor

1945AUgRadioCraftI’m not sure it would comply with modern OSHA rules, so whatever you do, make sure you don’t touch any of the exposed conductors. But if you need to quickly come up with a low voltage, this self-explanatory method of making your own resistor should do the trick. Measure the voltage, and keep adding salt until you get the desired voltage.

The idea appeared in the August 1945 issue of Radio Craft.  It had been sent in to the magazine by one Ollie Peoples of Mountain View, Oklahoma, who pointed out that if you can’t reach the desired voltage, then use a larger glass and add more salt.  He reported that the average glass wouldn’t deliver more than six volts, and would get unduly hot with that voltage.

As long as they’re careful with the high voltages involved, advanced students could use this idea as part of an interesting science fair project, demonstrating how changes in salinity affect the resistance.



WW2 Music at Work

1945AugRadioServiceDealerThis image could be mistaken for the studio of a small radio station, but it’s actual the public address console of a wartime industrial plant. Specifically, it’s the console of the RCA Plant Broadcasting System. It appeared in the August 1945 issue of Radio Service Dealer, as part of an article penned by the manager of RCA’s Music Library Service. The article is one of a series giving dealers ideas on how to promote the P-A business, and focused on providing music in the industrial environment.

Plant managers learned that by piping in the right mix of music, they would increase productivity and worker morale. Such sound systems were suitable for industrial plants, as well as office areas devoted to stenographic and clerical work. Business offices such as banks and insurance companies could play music both for workers and customers. And in hospitals, hotels, and stores, music could be piped in over sound systems.

RCA had the musical programming down to a science, and had packages of records available for sale to companies. Musical selections were broken down into four categories.

First of all, there was music for the opening period. These songs would play as workers arrived, and would continue for about fifteen minutes after starting time. These were invariably marches or patriotic tunes, such as “Stars and Stripes Forever,” or the “Washington Post March.” Other possibilities would be upbeat or fast tempo dance selections such as “Pennsylvania Polka.”

About an hour and a half after starting time, and again about an hour and a half before lunch, songs from the “Fatigue” playlist would be played. More songs from this list would be played similar times in the afternoon. Many of these were waltzes, and also popular hits, Latin and Hawaiian tunes, or old time favorites. Some songs on this list included “Green Eyes,” “Star Dust,” and “Begin the Beguine.”

The magazine stressed that the playlists had to be fine tuned to the audience. For example, it noted one small plant where about 75% of the workers were girls between 18 and 23. The music picked for that audience simply wouldn’t work at a plant where most workers were over 35.

RCA’s library also included some records for special occasions, such as Christmas songs and more patriotic tunes.

Workers at Davis & Geck, Inc., Brooklyn, N.Y., pack surgical sutures with the help of music piped in from wall-mounted RCA speakers.

Workers at Davis & Geck, Inc., Brooklyn, N.Y., pack surgical sutures with the help of music piped in from wall-mounted RCA speakers.

One office employed 600 girls doing monotonous filing duties. Normally, at about 3:00, fatigue would set in, but the author observed those 600 girls instead singing along softly with a popular recording. The office manager was initially skeptical, but experience showed that the vocals did not impede efficiency.

A plant with many Polish or Slavic workers would get more polkas and folk dances. One plant in Trenton employed mostly Italians, and that plant had almost every record Caruso ever made.

Toward this end, one service featured by RCA was a survey that could be given to workers and analyzed at headquarters in Camden, N.J. to come up with a custom record library from the RCA catalog. “The psychological effect of having the personnel feel that the music is theirs, played for them, gives them a personal interest in the project which is otherwise unattainable.” The overall effect was greater efficiency, less absenteeism, and better output.

On the other side of the Atlantic, Britain was also seeing to it that war workers had music. The BBC program Music While You Work was programmed following similar principles. One interesting rule for the BBC program was the banning of the song “Deep in the Heart of Texas,” due to the potential danger of workers taking their hands off their work to perform the hand claps in the chorus.



More Sourdough by U.S. Mail

A few months ago, as an experiment, we sent some sourdough starter through the U.S. Mail.  We previously posted the results from one recipient.  The other sample went to Keith at the Successfully Living Simpler blog, and he posted the results.  He claims that he made a “mistake” with the recipe, but I would say that he actually made an “invention” by inadvertently mixing two recipes to make these biscuits.

Early in the pandemic, many people simultaneously decided to take up baking, and yeast became almost impossible to find.  But a single package of store-bought yeast has now been used to make bread in three different states.  And in my refrigerator, I still have the means to continue making it indefinitely.

Electronics Illustrated

1970MayEIJust over fifty years ago, I was carefully perusing the letter addressed to my dad from Publisher’s Clearing House. The head honcho of that firm was Robert H. Treller, and he always took a personal interest in our family, since the letters were always full of personal handwritten notes directed to us.

Robert H. Treller was always eager to make sure we qualified for the big prize drawing, although we never got picked. I remember that one of the letters had testimonials from previous winners, one of whom happened to be in our local calling area. I still remember that they were in St. Paul Park, Minnesota. Just to make sure that Robert H. Treller was on the level, I actually called them to inquire whether they had really won the prize. Sure enough, the woman who answered the phone cheerfully assured me that Publishers Clearing House was legit.

Of course, Robert H. Treller wasn’t in the business of just handing out money, although that was a big part of it. He had magazines that had to be cleared out of the house at steep discounts. The envelope contained a sheet of stickers for the magazines, and you returned the ones you wanted to subscribe to. No money changed hands–they cheerfully billed you later.

Among the magazines with a sticker was one with the intriguing title of “Electronics Illustrated.” I don’t remember the price for a year’s subscription, but I’m sure it was close to zero. I affixed the sticker to the entry form and sent it in. And four to six weeks later, I received the issue shown above.

None of the projects in that issue jumped out at me as something that I wanted, but I do remember reading about DX’ing the Indian Ocean and the Phillipines. Also, I remember the Lafayette CB radios looked very intriguing, although way out of my price range. The stereo pictured on the cover was the Toshiba KS-1810H. But since I never did win a prize from the Publishers Clearing House, it was also well out of my price range at $99.95.