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DIY OLEDs

[Jeri Ellsworth] has put together a couple of videos that cover how she made her own organic light emitting diodes, or OLEDs. In the first video, after the break, it discusses the difference between regular, rigid semiconductor LEDs and organic LEDs. The video then goes on to show how to make an OLED as successive layers of materials. Indium tin oxide (ITO) on glass forms a transparent anode. That is then coated with PEDOT:PSS, a conductive polymer mix that is used as a hole transport layer. Then a red diamond ruthenium complex is added to create the emissive layer. The cathode layer is a low work function metal, initially, gallium indium eutectic alloy then later other metals were shown to work. The second video, shows how to juice a glowstick and make OLEDs with the liquid. The dye in blue glowsticks, 9,10-Diphenylanthracene, is an organic semiconductor and will emit light as an electric current is passed through it. The glow stick method seems to have some problems as the ITO coated glass plate is degraded by the glowstick chemicals. It would be interesting to see if using the porous aluminum or similar technique from [Jeri]‘s flexible electroluminescent displays could be used as an electrode.

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Climbing bike storage thwarts thieves?

If you’ve got an expensive bike and don’t mind carrying around a whole bunch of extra weight in your courier bag you’ll like this concept. A design team built a pole-climbing bike rack in about 14 days. The video after the break shows the prototyping process as well as the finished “lock” in use. It’s a commercial for the company that employs the designers, but this is one kind of advert we don’t mind watching.

Square channel makes up the body of the device, with a set of Rollerblade wheels which grab a light pole and use three 12V gear motors for climbing. The controller is a wireless fob similar to those used for keyless entry on cars. In the video you can hear the cliché sound of a car alarm being set once the carrier reaches its finished height. Nice.

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Warm Tube Clock

The Warm Tube Clock is the new kid on the block of Nixie Tube clocks. It takes inspiration from, and uses the same voltage driver circuit as the Ice Tube Clock. But this one uses four tubes instead of that hard-to-find single tube. It has a few other tricks up its sleeve. The shield that hosts the tubes has been designed for two different types. It also hosts an RGB LED for each tube, which adds the green glow seen above, and has a couple of small neon indicator bulbs which serve as the colon between hours and minutes.

The driver board centers around an ATmega328 running about three thousand lines of code. The firmware offers a lot of options including sound feedback, and a setting for every clock, calendar, alarm, and LED color toggle imaginable. See for yourself as the settings video, embedded after the break, walks you through each stage of the menu. We can’t help but think you need an instruction manual to set this thing up.

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Chumby webserver using upgraded internal storage

The Chumby One has an internal SD card offering a fair amount of storage. [Kenneth Finnegan's] came with a 1 GB card that had about 500 MB left over which he filled with a collection of MP3s. But he wanted to do more and so installed a pre-compiled version of lighttpd to act as a web server. The problem is that this binary requires a thumb drive to be plugged in because it maps the storage directory to the mounted USB folder. He wasn’t happy with that so he upgraded the internal SD card and rolled his own webserver to run from the internal SD card.

The upgrade involved going from a 1 GB to an 8 GB microSD card. In order to run the webserver internally he needed to recompile lighttpd to use a different root directory. This meant setting up an ARM cross-compiler and eventually finding a new place for the start up script. The location change for the ‘lighty’ directory leaves us wondering if a symlink couldn’t have solve the problem without recompilation. But we don’t have the hardware on hand to try this out ourselves.

But if you want to give it a shot, check out [Bunnie's] post about Chumby-based hardware. Looks like you can head out to the big-box store and have one in hand without shelling out too many clams.

Radar gun teardown

[Jeri Ellsworth] is at it again, this time she takes apart a hot wheels speed gun and in the process she does a good job of  explaining how radar can be used to measure speed.  She also demonstrates a way to determine if an object is approaching or receding from the radar gun.

The Doppler shift is one way to remotely measure the speed of an object. It works by measuring the change in frequency of a wave after it strikes an object. Rather than measuring the Doppler shift of the returning wave most radar guns use the phase shift. The reason is that the frequency shift of a relativly slow object (60mph), to a relitivly high frequency signal(10GHz) is small (about 0.893Hz), where the phase shift varies based on the distance of the object.  This is all just a stepping stone in her quest to build a crude TSA body scanner.

“Strong enough to lift a person, yet gentle enough to embrace a child.”

Tentacles have inspired fear and respect in humans long before anime came into the scene. Sailors shivered in their timbers at the thought of the great Kraken, or that octopus from 20,000 Leagues Under the Sea. It’s no surprise to know that humans have been trying to harness this fear and respect in technological form since the mid-20th century at least.

The fascinating world of tentacle robots has come a long way. It used to be that every breakthrough in tentaclebot technology had to be justified with either a military or misogynistic application, as demonstrated in this remarkable MIT project from 1968.

Thankfully our society has moved on since those misguided times, and while there is still the ever-present military-industrial complex to push for tentacled combat-omatons, forward-thinking people on the domestic front like [festo] demonstrate that at least some of us want to use tentacle robots for peace, love and food handling.

Catch the video after the break.

 

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Wiffletree: a mechanical digital to analog converter

This isn’t a hack. But it is a decidedly interesting piece of mechanical technology. The Whiffletree shown above is a way to turn binary data into a mechanical analog value. [Bill Hammack] explains how this assembly is used in a typewriter and how a whiffletree can convert binary data to a set of analog outputs.

These linkages are what makes an IBM Selectrix Typewriter work. You know, the one with the globe stylus instead of individual hammers for each key? [Bill] uses the typewriter as the example in his illustrations that show how each bit of data positions the output in a predictably different location. We’re familiar with other mechanical representations of binary data but converting to an analog value mechanically is a new concept for us. Lukily, the videos that [Bill] put together are fantastic at explaining the concepts. Not surprising, since he is a professor at the University of Illinois at Urbana-Champaign . See them both after the break.

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