Retrotechtacular: Cathode Ray Tube (CRT) Manufacturing

December 10, 2013 by Mike Szczys 21 Comments

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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Hanging Plotter With A Color Twist

December 10, 2013 by Phillip Ryals 16 Comments

[Jack Boland], a mechanical engineer at the University of Wisconsin, built a cool hanging plotter project called HangBot. It’s a fairly standard setup, where he converts an image to G-Code files, and it is plotted using two stepper motors for control. We’ve seen vertical plotters before, but they tend to only have a single pen. [Jack] expanded this one to bring color into the mix by splitting an image into separate CMYK layers, and plotting each onto separate transparency film. When overlaid, they create something close to a full color image. His idea is to use this setup as a replacement for typical window signage.

Since it’s drawing a continuous line, he appears to be employing a grid instead of a traditional dot pattern. That, combined with the inaccuracy of a marker tip means resolution will be limited. Still, you can tell that he’s made a great start in this (albeit blurry) photo. Check out the video of it’s operation after the break.

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Ultrasonic Data Transmission With GNU Radio

December 10, 2013 by Brian Benchoff 35 Comments

When we hear GNU Radio was used in a build, the first thing we think of is, obviously, radio. Whether it’s a using extremely expensive gear or just a USB TV tuner dongle, GNU Radio is the perfect tool for just about everything in the tail end of the electromagnetic spectrum.

There’s no reason GNU Radio can’t be used with other mediums, though, as [Chris] shows us with his ultrasound data transmission between two laptops. He’s transmitting audio from the speakers of one laptop at 23 kHz. It’s outside the range of human hearing, but surprisingly able to be picked up by a cheap desktop mic connected to another laptop. His GNU Radio setup first converts a string of text to a 5-bit packet, modulates it with FSK, and bumps up the signal to 23 kHz. On the other end, the data is decoded by doing the same thing in reverse.

The setup is easily able to reject all audio that isn’t in the specified frequency range; in the video after the break, [Chris] successfully transmits a ‘hello world’ while narrating what he’s doing.

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Disk-O-Mat: A Photobooth For Records

December 10, 2013 by Brian Benchoff 15 Comments

record

A photo booth is a simple concept – drop in a coin and get a few pictures in a couple of minutes. That’s only a visual record, though. What if you wanted to record audio? Thus the disk-o-mat was born.

The disk-o-mat is one of [flo]’s projects. In place of the miniaturized dark room found in a photo booth, [flo] put a record cutting setup. The 7″ records are polycarbonate sheets, each transferred to the turntable by a vacuum gripper. When the plastic disk is loaded, a stylus is set down on the disk and the record light goes on.

There isn’t a computer or any other digital means of saving audio and playing it back later. Everything is done just as how 45s – or more specifically, really old 78s – were cut; whatever goes into the microphone is cut directly into plastic.

The disk-o-mat was originally built in 2009, and has traveled to a few venues. [flo] is working on speeding up the process and making the machine a bit more reliable. Still, an awesome build and an awesome concept.

Videos below.

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Solar Powered, Tweeting Bird Feeder

December 10, 2013 by Phillip Ryals 3 Comments

The folks at Manifold created their version of a tweeting bird feeder, and [Chad] wrote up a behind-the-scenes of their design. The goal is something we’ve seen before: When the bird lands to eat, take a picture and tweet it. In this case, they had some corporate money behind the project, and that allowed them to buy a nice solar panel and battery pack to keep the whole thing running.

The write-up is full of the experimentation that we all enjoy: They found that detecting motion through the camera feed wasn’t reliable, so they switched over to a PIR sensor. The PIR sensor was too sensitive to heat changes during the day, so they went with an ultrasonic rangefinder, but wind caused issues there. They finally came up with a solution which involves using two sensors to confirm motion. This seems a bit more complicated than it needs to be, but it works well for them.

We think it is nice to see companies getting behind quirky projects. All told, they spent dozens of hours on this, and they chose to give all of their findings back to the community in the form of thorough explanations and project diagrams. It would be nice to see more of this.

The weather in Colorado hasn’t been the best lately, so the birdhouse hasn’t been tweeting for a while. In our experience, a project that’s turned off is in the dangerous position of being scavenged for parts. Hopefully that isn’t the case here, and we will see it back in action when Spring starts.