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Retrotechtacular: Tube Amplifiers

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It’s hard to beat this vintage reel for learning about how vacuum tube amplifiers work. It was put together by the US Army in 1963 (if we’re reading the MCMLXIII in the title slide correctly). If you have a basic understanding of electronics you’ll appreciate at least the first half of the video, but even the most learned of radio enthusiasts will find something of interest as they make their way through the 30-minute presentation.

The instruction begins with a description of how a carbon microphone works, how that is fed to a transformer, and then into the amplifier. The first stage of the tube amp is a voltage amplifier and you’ll get a very thorough demo of the input voltage swing and how that affects the output. We really like it that the reel discusses getting data from the tube manual, but also shows how to measure cut-off and saturation voltage for yourself. From there it’s off to the races with the different tube applications used to make class A, B, and C amplifiers. This quickly moves onto a discussion of the pros and cons of each amplifier type. See for yourself after the jump.

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Retrotechtacular: Films Used to Be Recorded on Film

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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: World’s First Color Movie

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It’s surprising how often a brilliant idea is missed out on until years after the fact. In this case the concept was seen publicly within ten years, but the brilliance of the inventor has been appreciated once again after 110 years. It’s a color movie which was filmed around 1901 or 1902 but it sounds like the reel wasn’t shown in its full color grandeur until 2012 when the National Media Museum in the UK started looking into the history of one particular film.

The story is well told by the curators in this video which is also embedded after the break. The reel has been in their collection for years. It’s black and white film that’s labeled as color. It just needed a clever and curious team to put three frames together with the help of color filters. It seems that [Edward Turner] patented a process in 1899 which used red, green, and blue filters to capture consecutive frames of film. The patent description helped researchers put image those frames — also using filters — to produce full color images like the one seen above.

The press release on the project shares a bit more information, like how they determined the age of the film using genealogical research and the fact that [Turner] himself died in 1904. The process didn’t die with him, but actual evolved and was exhibited publicly in 1909. This, however, is the oldest known color movie ever found.

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A beautiful pinhole camera takes wonderful photos

With digital cameras in everything and film slowly disappearing from shelves, everyone loses an awesome way to learn about photography. Pinhole cameras allow anyone to build a camera from scratch and also learn about those crazy f-stops, exposure times, and focal planes that Instagram just won’t teach you. [Matt] put up a great tutorial for building your own pinhole camera, and the project looks easy enough for even those who are still playing around with their cell phone cameras.

For film, [Matt] used 120 film, a medium-format medium that is sill available for purchase and processing in some areas. Because [Matt]‘s pinhole is relatively large and made out of very thin material, the camera could take very large pictures – much larger than standard 35mm fare. If you’re using a smaller camera projecting a smaller image onto the film, 35mm would be the way to go as it greatly decreases the difficulty of finding film and a processing center.

[Matt]‘s camera is constructed out of laser-cut plywood. Because he’s producing extremely wide images with his camera (6 x 17cm), [Matt] needed to curve the film around the focal plane of the camera to keep the entire image in focus.

The mechanics of the camera are simple – just a pair of knobs to wind the film and a small metal shutter. [Matt] added a shutter release cable to open and close the aperture without moving the camera and had a wonderful camera perfect for capturing either sirs and madams or Civil War battlefields.

Camera dollies hacked together by stop motion filmmakers

A little bit of technology goes a long way when it comes to stop motion animation. In this case it’s a trio of simple camera dollies built during production of a short film called The Maker.

A Dolly is a method of mounting the camera so that it can be moved smoothly during a shot. Of course with stop motion the movement actually happens between the shots so it’s even more important that the camera be moved accurately. The video after the break shows off how they added CNC control for the camera. The first dolly was built from a pair of PVC pipes with a sled that moves along them. A motor moves a loop of 35mm film which is attached to the dolly. This is a great choice of materials since it doesn’t stretch and it’s free (one of the filmmakers is a projectionist). The next dolly is made from a flatbed scanner, and the final offering is seen above. Built from a bicycle wheel it provides a stationary platform above the hub for the models, while the camera rotates on an arm attached to the wheel. You can watch the complete film here.

If you’re looking for more inspiration check out this dual-axis PVC dolly project.

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F/stop printer for analog printing black and white photos

This beautifully crafted device is a timer used for getting the perfect exposure when making film prints of photos. But in addition to keeping time, it also does logarithmic calculations that are based on the f-stop values used for each exposure. It does this in 1/100th of a stop increments. While he was at it, [William] also decided to pack in a bunch of other features like dry down correction, and support for making test strips. This is a little hard to understand when discussed in the abstract, but just take a look at his video after the break where [William] walks us through an example exposure and all will become clear.

You can see from the construction page that the device is basically an Arduino shield. It provides a relay for controlling the exposure lamp, a keypad, rotary encoder, and character LCD. Slap it in a fancy case, connect it to the equipment you’re using, and you’ll be creating perfect prints in no time flat!

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Flimsy Pi case still provides a level of protection

This flimsy case isn’t going to protect your Raspberry Pi if you knock it off the workbench. It will provide a level of protection against shorting out from contact with metal objects, or from liquids spilled in the near vicinity. [CGPatterson] ended up making this case from a single sheet of transparency film.

The project is basically papercraft. He started with the dimensions published on the Raspberry Pi FAQ, which turned out to be wrong. Not having a caliper available to help with the precision of the measurements, he grabbed his ruler and did the best he could. The first two cases were a poor fit, but as you can see the third is like a glove. Luckily you don’t have to go through this same trial and error as he release the design. Both A4 and US Letter sized PDFs are available for download. Print them out on the transparency, cut along the lines, apply transparent double-sided tape to the tabs and you’re in business. If you wish to alter the design he has also posted the SVG source he made in Inkscape.

This is certainly a good option for those of us without the ability to produce laser cut parts.