Weekly roundup 1/28/12


Another week has passed and it is time to review the best of what hit our blog in the past week.

In first place is a repeat from last week showing how you can turn an Android device with a CMOS camera into a radiation detector.

In first place if we ignore repeats is a post about how the Raspberry Pi board can decode 1080p video! We’re just itching to get our grubbly little hands on some of these guys when they are finally released.

Up next is a project from one of our own. This week [Brian Benchoff] put up a post about how he built a manifold clock after seeing a similar project on Kickstarter.

Following that is a post showing how you can overlay video onto an encrypted HDMI signal. The MPAA would probably like to crack [bunnie] over the knuckles with a ruler for this one but he actually isn’t decrypting anything. Instead, he is encrypting the overlay and just replacing the normal video with it.

We like this next one a lot because it not only is a nice hack but it allows you to subtly control what can and cannot happen around you. Specifically, you can jam remote control helicopters with this device. It probably wouldn’t be too hard to pair this up with a TV B Gone to keep people from turning the TV back on once you have wrought your mischief.

Finally, another really neat one for you. In this post, we show [Sprite_tm's] radio transmitter that is composed out of two button cell batteries, two lengths of wire and an ATtiny processor. It is amazing that this even works but with the right tools, a good hacker can do just about anything.

Followup: Troll physics solved

A month ago, we saw a marvelous demonstration of troll physics from YouTube user [Fredzislaw100]. In his video, we saw a circuit of three switches and three LEDs wired in series and but not acting like the should. A lot of the comments for this post elicited reasonable explanations like modifying the battery or pure camera wizardry via After Effects. Thankfully, [Alan] stepped in and showed us how it was done. The solution uses two AC power sources with diodes in two of the switches and LEDs and inductors in the third pair. [Alan]‘s build was rather large compared to the original video, so we were wondering how this circuit could be made invisible.

[Fredzislaw100] just posted a video on how he did it. Like [Alan]‘s build, it uses two AC power sources, diodes, and inductors. In contrast to every single guess about where the circuit is hidden, the majority of the build is inside the battery connector. [Fredzislaw] did some amazing work hiding a 74LV132 quad NAND Schmitt trigger inside the battery connector. The diodes were easily hidden on LEDs 1 and 3 with some red nail polish, but we’re amazed by the inductor built into the LED seen in the title pic.

So there you go. With a ton of electronics know-how and an extremely steady hand (and a microscope), you too can build your own troll circuit. Check out the video after the break.

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DSLR performance measured with audio editing software

[Jaroslav's] camera didn’t have a feature to measure the speed of its response in different modes so he figured out his own method. Using the microphone on his webcam he recorded the sound made by the mirror and shutter movements, then used Audacity to analyze the camera’s performance.

When you get right down to it, this is a fantastic idea. Audacity, the open source audio editing suite, has the ability to show each captured audio track next to each other. That makes it easy for you to precisely align the clips, and has in-build time measuring features with fantastic resolution.

He tested a whole bunch of different settings on a Canon EOS600D DSLR camera. In the image above you can see him comparing performance between different ISO settings. He also looks into different brands and sizes of SD storage cards, as well as the time difference when storing raw image data versus JPEG encoded data.

[Jackson Pollock] is now a robot

Even though abstract expressionism died out several decades ago, robots are still chugging along dripping nihilistic pigment onto a cold, uncaring canvas. [Liat] and [Assaf] created a robot named The Originals Factory to create paintings in the style of abstract expressionism, a style of painting that is arguably best represented by [Jackson Pollock] and his ‘drip paintings.’

The build is surprisingly simple – there are four containers filled with C,M,Y, and K pigments. Pumps transport these paints to a print head mounted on an aluminum rail above a canvas. The software portion of the build is rather interesting. Instead of pixels, the image is rendered in ‘vixels’ – vertical lines of a specific length and color. Although we don’t see any examples of more precise work, [Liat] tells us The Originals Factory can be used to plot graphs on the canvas.

Check out a video of The Originals Factory squirting paint down a canvas after the break.

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How to add flair to a webpage that shows your project data

This temperature display may not knock your socks off, but it’s a simple demonstration of how you can used vector graphics as a web readout for data (translated). [Luca] wrote this four page tutorial to help others, he makes it look really easy, and the sky’s the limit on eye candy once you get he basics in place.

The first step is to create the dynamic SVG (vector graphic) file using Inkscape that will be used by the webpage. This starts with a static background, in this case the grey parts of the thermometer which will not change. Over the top the blue parts were added, with just a bit of XML editing to give those parts a hook which will be used in the next step. The demo above will have a moving blue bar and changing numeric output to match data coming in from a temperature sensor.

An SVG file is just a text file that is rendered as a graphic when loaded. [Luca] shows you how to used the identifiers set up when making the graphic to dynamically change the size and value of the blue parts with server-side PHP before sending the graphic to the browser. With that in place you just need to give the PHP file access to the data. He shows how to use the Pachube API but you could just as easily get this via serial or otherwise.

Synthesize with a hard drive

If you’d like a pseudo-mechanical way of producing a droning synthesizer sound, [gijs] is your man. He made a small synthesizer out of nothing but an old hard drive and a few components.

Whenever a disk platter is spun manually, the spindle motor inside the drive produces a few out of phase sine waves on its connections. [gijs]‘ synthesizer compares and amplifies these sine waves and sends them out to a speaker. The result is a strange droning chiptune-esque arpeggio.

The circuit for the build is soldered directly to the hard drive enclosure Manhattan style. Because the output of the spindle motor produces out of phase sine waves, [gijs] thought it would be a good idea if he could capitalize on some phase interference to alter the timbre of his synth. The entire build is mounted to a wall with hinges to one side so the speaker can be moved around. It isn’t much of a change, but we can here some wave forms cancelling each other out.

Check out the video of the build after the break. There’s also a few audio samples available on the project page.

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@publictextbox is a Twitter enabled phone booth

In the interests of open communication in shared spaces, [dan] made a public text box that serves as a terminal to the @publictextbox twitter account. We could see something like this being useful in a hackerspace or other hang out to announce to the world the happenings of the resident makers and builders.

The software setup is very simple and can run on just about any old computer you might have lying disused in a corner. The app is built with Processing, and the code is extremely simple and easily modifiable. Even though the case is a lovely cardboard number, the Twitter Box can be dressed up as any imaginable form. We’d love to see a nice TARDIS blue, but we’ll leave that up to [dan].

You can check out the demo of the Twitter phone box after the break. Alternatively, you could re-tweet this post and take part in a load test for the @publictextbox.

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