LED artwork disappears right before your eyes

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If you walked into an art gallery and saw nothing but blank canvases lining the wall, you might be compelled to demand your money back, or assume that you had discovered the world’s laziest artist. If this gallery happened to be displaying work by [Brad Blucher and Kyle Clements] however, you would be mistaken.

These two artists have collaborated to create a series of works titled, “Take a Picture“. Each picture they have built is constructed to look like an empty canvas when viewed with the naked eye. If you were to take a picture of the canvas with your cell phone or digital camera however, a whole new world would open up in front of your eyes. Their artwork is constructed using infrared LEDs, which cannot be seen with the naked eye, but are visible to nearly any CMOS or CCD sensor on the market. The images range from simple smiley faces and objects to abstract geometric shapes.

It’s a very simple, yet novel approach, and we happen to think it’s pretty cool. The artists have not said what they have planned for this project in the future, but we’d love to see it expanded using larger LED arrays to display higher-resolution images, or even short movies.

Keep reading to see how they went about creating these works of art as well as a promo video demonstrating the effect.

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Remote operated security gate lets you phone it in

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[Itay] has a friend who works in a rented office where the parking lot is secured by a remote-controlled gate. Unfortunately, while his friend shares an office with several people, they only received a single remote. To help his friends out, he built a small device that triggers the remote control whenever a phone call is received.

The remote modification was rather straightforward. He simply opened the device, adding a single wire to each button terminal. Rather than connect to the remote using wires, he decided to fit it with what looks like a scavenged DC power jack. The ring detector circuitry was constructed and stuffed in a small phone box, which is connected to the remote using a DC power plug. It’s a great solution to the problem, but let’s just hope no one gets a hold of the phone number they used for the trigger!

There are plenty of pictures on his site, as well as video of the ring detector being tested. Unfortunately [Itay] lost the original schematics for the circuit, so you will have to flesh that part out on your own if you wish to build a similar device.

Keep reading to see a few videos of the remote in testing and in use.

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A different take on a laser projection microscope

[Dusjagr] has another take on building a laser projection microscope. Last year we saw a laser-based microscope that shined the beam of light through a water droplet which contained the subject to be magnified. The droplet bent the focused beam of light and projected the magnified contents onto a screen. Now that’s pretty neat and [Dusjagr] has used that method himself. But most traditional microscopes use glass slides to contain the subject and this new version now makes that possible.

A bit of experimentation led [Dusjagr] to the discovery that a lens re-purposed from a webcam can achieve similar focus results as a water droplet. The video after the break shows the apparatus seen above in action. The laser shines through the lens, then through a slide that contains a water sample from a nearby pond. The image is clear, albeit completely bathed in green.

For us the most interesting part of [Dusjagr's] writeup is his discussion of the limits of laser amplification based on the wavelength of light the diode puts out.

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How to find WiFi: carry a big stick and use long exposures

Here’s an artsy way to map out WiFi networks around you; use a big light pole and long exposures to graph them on top of photographs. This capture method is often called light painting, and uses the relative brightness of LEDs to stretch out a still image – moving the stick quickly while the shutter is open.

The four-meter tall rod used in this project plays host to 80 white LEDs. An Arduino along with a WiFi shield detect the relative signal strength of the network surrounding the device. The images that are produced with this method are quite pleasing and you’ll enjoy watching the video after the break. We just wish that there was some kind of Google Street View interface to share this data since someone had to go out pounding the pavement with the rather peculiar looking apparatus in order to gather the data in the first place.

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Pint-sized Nixie display fits neatly in your pocket

[Brett] has had Nixie tubes on the brain ever since being introduced to them by a good friend of his. He decided that building a Nixie-based key chain would be the best way to familiarize himself with the technology, while also giving him a project to enter in the 555 Design Contest. He dug up the smallest Nixie tube he could find that displayed digits, and got down to business.

The biggest obstacle he ran into was figuring out how he would provide the high voltage required to light the Nixie tube. He eventually built a transformer circuit driven by a 555 timer, using a small 12v battery as his power source. Once everything was up and running on a breadboard, he designed and etched some PCBs, then soldered everything together.

The end result is a nifty little key chain that flashes the number 5 when a button is pressed – pretty appropriate for the 555 contest. It’s a great looking project, though we’re still not 100% sure what we think about a naked high voltage circuit residing in our pocket.

Keep reading for a pair of videos documenting the key chain’s construction and operation.

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This robot will school you at freethrows

People spend years of their lives practicing on the courts to get the kind of accuracy that this robot achieves. It is able to shoot freethrows thanks to stereoscopic camera analysis of the target. We know what you’re thinking; big deal, it knows the distances which makes the calculations easy. That’s not the case, look a bit closer in the image above. The basket itself is mounted on a robotic platform and creates a randomly moving target. It looks like shots are only taken when the basket is stationary. But still, that means the system is able to calculate accurate throws when the basket is not only at varying distances, but also when it is not directly in front and not square to the arm of the robot. The accuracy relies on analyzing the square on the backboard of the basket. Because two cameras give different perspectives, edge and corner detection of both images allow the system to extrapolate the location of the target.

After the fold there’s a video of this robot being demonstrated to the public. Apparently the yellow-armed-monster isn’t suitable for public consumption because the developers have covered it with the body of a plush seal.

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Earthquake alert system

 

[Roteno's] submission for the 555 timer design contest is an Internet connected earthquake alert system. It monitors the USGS website for earthquake data and plays a tune when an earthquake occurs. The data is available as a feed in the form of a TXT file which is pretty easy to parse using cURL. He chose an LPCXpresso board (which is an ARM development platform that can run a Linux kernel) along with an XPORT module to handle the Ethernet traffic.

So where does the 555 timer see some action? It is responsible for playing the tone when an earthquake is detected. But playing just one pitch isn’t much fun. Instead, [Roteno] built the circuit above which creates a resistor network switched by a series of transistors. This way he can use GPIO from the microcontroller to choose different pitches. Check out the video after the break to hear the results. At power-up all eight pitches are played as a test, and the alert sound varies in pitch and tempo based on the magnitude of the earthquake.

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