Retrotechtacular: Crystals Go to War

More than one of our readers suggested we highlight this beautifully-shot process documentary about the laborious and precise manufacturing of piezoelectric quartz crystals in the early 1940s. Just a few years later, Bell Labs would perfect a method of growing synthetic crystals, sending droves of brave men and daintily-handed women from the Reeves Sound Laboratories to the unemployment line.

Early radio equipment relied upon tuned or L-C circuits for clocking. These were prone to drift by a few kHz, which prompted the use of crystal oscillators for stable frequencies in the 1920s. The lives of our armed forces and those of our WWII allies depended on reliable communication equipment, so the crystal oscillators they used were top shelf, produced by hand from Brazilian crust.

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Retrotechtacular: Step Up and Get Your Transformer Training

Whether you’re just getting into electronics or could use a refresher on some component or phenomenon, it’s hard to beat the training films made by the U.S. military. This 1965 overview of transformers and their operations is another great example of clear and concise instruction, this time by the Air Force.

It opens to a sweeping orchestral piece reminiscent of the I Love Lucy theme. A lone instructor introduces the idea of transformers, their principles, and their applications in what seems to be a single take. We learn that transformers can increase or reduce voltage, stepping it up or down through electromagnetic induction. He moves on to describe transformer action, whereby voltages are increased or decreased depending on the ratio of turns in the primary winding to that of the secondary winding.

He explains that transformer action does not change the energy involved. Whether the turns ratio is 1:2 or 1:10, power remains the same from the primary to the secondary winding. After touching briefly on the coefficient of coupling, he discusses four types of transformers: power, audio, RF, and autotransformers.

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Retrotechtacular: Teleprinter Tour, Teardown

This week, we’re taking the wayback machine to 1940 for an informative, fast-paced look at the teleprinter. At the telegram office’s counter, [Mary] recites her well-wishes to the clerk. He fills out a form, stuffs it into a small canister, and sends it whooshing through a tube down to the instrument room. Here, an operator types up the telegram on a fascinating electro-mechanical device known as a teleprinter, and [Mary]’s congratulatory offering is transmitted over wires to her friend’s local telegraph office hundreds of miles away.

We see that the teleprinter is a transceiver that mechanically converts the operator’s key presses into a 5-digit binary code. For example, ‘y’ = 10101. This code is then transmitted as electrical pulses to teleprinters at distant offices, where they are translated back into alphanumerical data. This film does a fantastic job of explaining the methods by which all of this occurs and does so with an abstracted, color-coded model of the teleprinter’s innards.

The conversion from operator input to binary output is explained first, followed by the mechanical translation back to text on the receiving end. Here, it is typed out on a skinny paper tape by the type wheel shown above. Telegraphists in the receiving offices of this era cut and pasted the tape on a blank telegram in the form of meaningful prose. Finally, it is delivered to its intended recipient by a cheeky lad on a motorbike.

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Retrotechtacular: Multi-Purpose Military Magazines Make Maintenance Memorable

Whether you’ve been following Retrotechtacular for a while or have firsthand experience with the U.S. Army, you know that when they want to teach something to a someone, they’ll get the job done in spades with a side of style. The era between WWII and the Vietnam War was a golden age of clear, simple instruction that saw the Army use memorable material to teach a wide array of topics. And speaking of golden ages, the Army found success with comic book-style instructional magazines drawn chiefly by [Will Eisner] of Spirit fame.

ps-coverThe first of these rags was called Army Motors, which premiered in 1940. It introduced several memorable characters such as a Beetle Bailey-esque bumbling soldier named Private Joe Dope, and no-nonsense gal mechanic Connie Rodd, a sharp cookie who’s as brainy as she is buxom. Educational and entertaining in equal parts, the magazine was pretty well received.

Its successor, known simply as P.S. started its run around the beginning of the Korean War in June 1951. These magazines were intended as a postscript to the various equipment maintenance manuals that soldiers used. They offered all kinds of preventive maintenance procedures as well as protips for Army life. The eye-catching depictions of Connie Rodd demanded soldiers’ attention while the anthropomorphic equipment illustrations encouraged them to listen to what their equipment told them.

Additional artists including [Joe Kubert] and [Dan Spiegle] were brought in to produce P.S. on a monthly basis. As the years marched on, the magazine’s character base expanded to include representatives of other military branches solving specialized problems. The bumbling idiot types were 86’d pretty early on, but cheesecake was served well into the 1970s.

Did we mention that they’re still making P.S.? Here’s the February 2015 issue and a friendly PDF warning.

Thanks for the tip, [Itay]!

Retrotechtacular is a weekly column featuring hacks, technology, and kitsch from ages of yore. Help keep it fresh by sending in your ideas for future installments.

Retrotechtacular: ⋅⋅⋅⋅ ––– ⋅–– – ––– –– ––– ⋅–⋅ ⋅⋅⋅ ⋅ –⋅–⋅ ––– –⋅⋅ ⋅

There’s a lot to learn from this 1966 Army training film about the International Morse Code, but the most crucial component of good keying is rhythm. A young man named [Owens] demonstrates very clean keying, and the instructor points out that skill is the product of sending uniform and short dits, uniform and short dahs, and correct spacing between dits, dahs, letters, and words.

Throughout the film, there are title cards in a typeface that shows the stroke order of military printing. The instructor points this out after a brief interlude about the phonetic alphabet (Alpha, Bravo, Charlie, &c). Right away, we see that the Morse Code for ‘H’ is four dits that gallop with the rhythm of a horse in a hurry to get to the hotel.

big keySuch clever and memorable pictures are painted for a few other letters. We wish he would have covered them all, but that’s not the aim of this film. The Army is more concerned with good, clean rhythm and proper spacing that marks the difference between ‘low’ planes and ‘enemy’ planes. There’s a simple, three-step plan to getting what is called a ‘good fist’, and the Army demonstrates this in the best possible way: a giant J-38 and fake hand descending from the ceiling to match. Yes, really.

The first step is to adjust the key to ensure good contact alignment, proper gap spacing, and ideal spring tension. The second step is to develop good technique by resting one’s elbow on the table and holding the key rather than slapping it. The third step is simply to practice. Learning through imitation is helpful, as is taping one’s practice sessions and playing them back. [Owens] likes to use an RD-60 code recorder, which immortalizes his signals in ink.

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Retrotechtacular: The Gossamer Condor

For centuries, human-powered flight eluded mankind. Many thought it was just an impossible dream. But several great inventions have been born from competition. Challenge man to do something extraordinary, offer him a handsome cash incentive, and he may surprise you.

In 1959, London’s Aeronautical Society established the Kremer Prize in search of human-powered flight. The rules of the Kremer Prize are simple: a human-powered plane must take off by itself and climb to an altitude of ten feet. The plane must make a complete, 180° left turn, travel to a marker one-half mile away, and execute a 180° right turn. Finally, it must clear the same ten-foot marker. While many tried to design crafts that realized this dream, man is, at his strongest, a weak engine capable of about half a horsepower on a good day.

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Retrotechtacular: The Sylvania Tube Crusher

This week, we’re switching off the ‘Tube and taking a field trip to Emporium, Pennsylvania, home of the Sylvania vacuum tube manufacturing plant. Now, a lot of companies will tell you that they test every single one of their products, ensuring that only the best product makes it into the hands of John Q. Public. We suspect that few of them actually do this, especially these days. After all, the more reliable the product, the longer it will be before they can sell you a new one.

sylvania-tube-crusher-thumbFor Sylvania, one of the largest tube manufacturers of the golden age, this meant producing a lot of duds. A mountain of them, in fact, as you can see in the picture above. This article from the January 1957 issue of Popular Electronics vilifies forgers who used all kinds of methods to obtain defective tubes. They would then re-brand them and pass them off as new, which was damaging to Sylvania’s good name and reputation.

In addition to offering a reward for turning in known tube forgers, Sylvania did the most reasonable thing they could think of to quash the gray market, which was building a tube-crushing machine. Pulverizing the substandard tubes made sure that there were no “factory seconds” available to those fraudsters. After crushing shovelful after shovelful of tubes, the glass splinters were removed through a flotation separation process, and the heavy metals were recovered.

Did we get you all hot about tubes? Here’s how Mullard made their EF80 model.

[Thanks for the tip, Fran!]

Retrotechtacular is a weekly column featuring hacks, technology, and kitsch from ages of yore. Help keep it fresh by sending in your ideas for future installments.