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Retrotechtacular: Submarine Cable Splicing is Serious Business

Really. As this wonderfully narrated talkie picture from 1939 will attest, keeping even one drop of water from penetrating undersea cables is of the utmost importance.

How do they do it? Many, many layers of protection, including several of jute wrapping. The video centers on splicing a new cable to an existing one in the San Francisco Bay to bring the wonder of telephony to a man-made island created for the Golden Gate International Expo.

The narrator makes these men out to be heroes, and when you see how much lead they came into contact with, you’ll understand what he means. Each of the 1,056 individually insulated wires must be spliced by hand. After that comes a boiling out process in which petrolatum is poured over the splice to remove all moisture. Then, a lead sleeve is pulled over the connections. Molten lead is poured over the sleeve and smoothed out by hand.

At this point, the splice is tested. The sleeve is punctured and nitrogen gas is pumped in at 20psi.  Then comes the most important step: the entire sleeve is painted with soap suds.  Any gas that escapes will make telltale bubbles.

Once they are satisfied with the integrity of the sheath, they wrap the whole thing in what appears to be lead cables and pound them into submission. Surely that would be enough, don’t you think?  Nope.  They weld the cables all around and then apply two coats of tar-treated jute wrapping, which retards saltwater corrosion considerably.

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Retrotechtacular: Films Used to Be Recorded on Film

retrotechtacular-movie-film-photo-finishing

We’re sure that this title makes some readers itch because there are still a number of well-respected directors who insist on shooting with film rather than digital, but the subject of this week’s Retrotechtacular shows a portion of the movie industry that has surely been relegated to life-support in the past few decades. Photo finishing, once the stronghold of chemical processes used by all to develop their photographs, has become virtually non-existent. This is the story of how film and photo finishing drove cinema for much of its life.

The reels seen above are negative and positive film. The negative film goes in the camera and captures the images. After developing and fixing the negative film, the process is repeated. Light shines through the fixed negative in order to expose a fresh reel of film. That film is finished and fixed to create the reel which can be used in a projector. This simple process is covered near the beginning of the clip found below. The 1940 presentation moves on to discuss the in-depth chemistry techniques used in the process. But you’re really in for a treat starting about half-way through when the old manual methods are shown, which have been replaced by the “modern laboratory”. We love those huge analog dials! The video concludes by showing the true industrialization of the film developing process.

We’re running out of Retrotechtacular topics. If you know of something that might be worth a feature please send in a tip!

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Retrotechtacular: Cathode Ray Tube (CRT) Manufacturing

retrotechtacular-crt-manufacturing

This week we return to the grainy and un-color-corrected goodness that is synonymous with ancient video reels. [CNK] sent in a tip to a set of videos showing how Cathode Ray Tubes are manufactured on a massive scale. You’ll want to watch the pair of clips embedded below which total about 18 minutes. But there’s also some background to be found at this post from the Obsolete Technology Telley Web Museum.

The video presentation starts off with a brief overview of the way a color CRT works. It then moves to a factory tour, carefully showing each step in the process. The footage was shot in the 1960′s and because of that we catch a glimpse of some vintage equipment, like that used to measure the curvature of the CRT glass. You may be thinking that the world of CRT is in the past, but not so. We think there may even been a coming fad of producing them in your home lab.

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Retrotechtacular: An Ax Factory of Yore

retrotechtacular-ax-factory

When your mind’s eye thinks of an ax factory you may envision workers loading blanks into a machine that refines the shape and profile before heading to an annealing furnace. But this is Retrotechtacular, and we’re tickled to feature a look at a different time in manufacturing history. This ax factory tour looks at every step in the manufacturing process at a factory in Oakland, Maine. It was shot on film in 1965 just a few months before the factory shut down. [Peter Vogt] did a great job of shooting and editing the reel, and an equally fine job of converting it to digital so that we can enjoy it on his YouTube channel.

Above you can see the automatic hammer — known as a trip hammer — that is driven by cam action. At this point a lot of work has already been done. Blanks were cut from steel bars by two workers. These were shaped on the trip hammer before being bent in half to create the loop for the ax handle. From there a piece of high-carbon steel was added to form the cutting surface. This brings us to the step above, shaping the two glowing-hot pieces into one.

We don’t want to undermine the level of craftsmanship, and the labor-intensive process shown off here. But we can’t end this write-up without at least mentioning the kitsch that is smoking cigarettes and pipes on the job. At one point a worker actually lights his pipe using a the glowing-hot ax head.

To give you an idea of how this contrasts with modern manufacturing, here’s How It’s Made episode on axes (although we think whats being made would more appropriately be called hatchets).

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Retrotechtacular: WWII Paraset Spy Radio Used by French Resistance

Paraset

[Robert Sumption] a.k.a [W9RAS] takes on the daunting challenge of building a WWII spy radio called the Paraset as the topic of this week’s Retrotechtacular. It was originally a tube based CW (Morse code) transmitter/receiver used by the French underground to communicate with the Allies. Many of these radios were dropped behind enemy lines and could run on European AC or 6 V DC with the added advantage of being able to use most anything for an antenna, including fence wire. These small, low power and highly mobile radios tuned in the 3 to 8 MHz range were instrumental in the resistance. But they still make for a really fun scratch-built radio project.

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Retrotechtacular: [Zoltán Bay’s] Moon Bounce Coulometer Signal Amplifier

coulometers and antenna

In the years before World War II it was theorized that shortwave radio waves could propagate through the ionosphere relatively undisturbed and allow for a signal to be bounced off the moon and returned. [Zoltán Bay] calculated that the return signal would be too faint to be detected above background noise with the radio receiving equipment of the day. To overcome this receiver dilemma he devised a new receiving element consisting of 10 coulometers sharing a common tank of a water solution. Each of the coulometers had a separate electrical connector and when current flowed through the electrode, hydrogen bubbles would form in an attached glass capillary column. By periodically sweeping through all 10 coulometers using a rotating switch attached to the radar receiver, any radar echo as well as random background noise would be readable by the amount of bubbles in the capillary columns. A single radar echo would be indistinguishable from random background noise in the columns of bubbles, but if the sweep is continued for 30 minutes any periodic radar echo would show as an increased accumulation of bubbles in a respective column. By reading these coulometers and knowing the switching period you could determine that you were receiving a true radar echo from the moon.

What an amazing apparatus to amplify a periodic signal above background noise! Nowadays we would call this a long-time integrator or persistence measurement and it’s a relatively simple task. You can download and read [Zoltán Bay’s] paper on “Reflection of Microwaves From the Moon” dated 1946 in PDF form. His integrator apparatus details start on page 17.

It took some years but in 1946 [Zoltán Bay’s] receiving apparatus was tested and did confirm reception from moon bounce. However, U.S. Army Signal Corps with better crystal frequency stabilized equipment was able to perform the same task earlier as seen in the below video without the use of an integrator. Even though the U.S. Army equipment was superior for this task [Zoltán Bay’s] apparatus enjoyed years of service in the field of planetary radar observation where such a high sensitivity scheme was still necessary.

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Retrotechtacular: Upgrading Train Signaling Before the Information Age

retrotechtacular-british-railway-signaling

What’s surprising about the subject of this week’s Retrotechtacular is that the subject is not from that long ago. But looking at the way in which the work was done makes it feel so far in the past. In 1974 the British Railways Board set out to modernize and interconnect the signaling system. What you see above is one of hundreds of old signal control houses slated to be replaced by an interconnected system.

These days we take this sort of thing for granted. But from the start of the project it’s clear how the technology available at the time limited the efficiency of the development process. We’re not talking about all of the electro-mechanical parts shown during the manufacturing part of the video. Nope, right off the bat the volumes of large-format paper schematics and logic diagrams seem daunting. Rooms full of engineers with stacks of bound planning documents feel alien to us since these days even having to print out a boarding pass seems antiquated.

With fantastic half-hour videos like this one available who needs television? We’d recommend adding this to your watch list so you can properly enjoy it. They show off everything; manufacturing the cables, stringing them between the signal towers, assembling the control panels, testing, and much more.

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