Monitor your heartbeat with a webcam and a flashlight

After seeing some heart rate monitor apps for Android which use the camera and flashlight features of the phones, [Tyson] took on the challenge of coding this for himself. But he’s not using a smart phone, instead he grabbed a headlamp and webcam for his heat rate monitor.

To start out he recorded a test video with his smart phone to see what it looks like to cover both the flash LED and camera module with his thumb. The picture is mainly pink, but there’s quite obviously a color gradient that pulses with each gush of blood through his skin. The next task was to write some filtering software that could make use of this type of image coming from a webcam. He used C# to write a GUI which shows the live feed, as well as a scrolling graph of the processed data. He took several tries at it, we’ve embedded one of the earlier efforts after the break.

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Morse Code interpreter

[Sulaiman Habsi] and two classmates put together a Morse Code interpreter as a class project at Sultan Qaboos University. The system listens to a morse code signal using a microphone, then translates that input to text which is displayed on this character LCD.

The breadboarded circuit feeds an audio signal from the microphone, through an OpAmp, to the ADC of an ATmega8 microcontroller. The captured signal is stored as a byte in a special way. The three least-significant bits signify how many total dots or dashes are contained in the character, the remaining bits represent those dots and dashes with zeros and ones. A full description of this process is included in a PDF linked in the article above. As you can see in the video after the break, the hardware waits to process all of the signals once the full message has been received.

This would be a great add-on for a Morse Code practice keyer.

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Digital stethoscope can record, playback, and analyzer heart sounds

It’s somewhat amazing how these rather inexpensive electronics can augment the functionality of a common stethoscope. This digital stethoscope is using audio processing to add the features. A standard chest piece feeds a condenser microphone which is fed through a pretty standard OpAmp circuit which supplies the ADC of an ATmega644. After being digitized, the heart sound can be recorded in ten second increments to a 1 Mb flash memory chip. The data can also be fed to MATLAB via a USB cable in real-time. There it is displayed as a waveform and the heart rate is calculated on the fly. Check  out the video after the break for a great demo of the system.

The picture above shows a set of ear buds used as output. But this is a standard headphone jack, so the heart sounds can be played on speakers which we think would come in handy for teaching purposes. There’s also the option to hook it to a computer input which could be the audio used for a Skype session if a doctor is not close at hand. There is lots of potential here at a fairly low cost and we love that!

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Defying gravity for new user interfaces

[Jinha Lee] at the MIT Media Lab created a new interface allowing new ways to modify and play with 3D objects. It’s called ZeroN, and it’s nothing short of a futuristic device straight out of Star Trek.

ZeroN is simply a platform for levitating a small spherical permanent magnet in 3D space. It does this by mounting a hall effect sensor on an electromagnet. The hall sensor measure the strength of the magnetic field of the ball every few milliseconds and keeps the spherical magnet levitated. To move the object in 3D space, a few webcams track the ball over the platform and tell the electromagnet to move on a CNC-like x y table.

[Jinha] showed off a lot of cool stuff that is possible with the ZeroN; ping-pong is by far the coolest implementation, but it’s also possible to use the magnetic sphere to demonstrate n-body gravity or as a camera flying around a digital scene.

It’s a really amazing piece of work with an exceptional demo video. You can check that video out after the break. Thanks, [ferdinand] for sending this one in.

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Pleasing results from a CNC mill project

[Roy] is getting to the end of his second CNC mill project and finally seeing some results. Here you can see a bear he milled in some floural foam.

The project started out as an Arduino-based pen plotter. It move the pen along one axis, and the drawing surface along another, with the third axis allowing the pen to be lifted and repositioned. With that in his back pocket he went all out and began what he calls the Mark II. He used T-slot aluminum for the frame, which really helped when it came to aligning the linear rod supports for each axis. After a lot of drilling, and tapping he managed to bring each axis on line one at a time. A pre-fab CNC driver kit drives the stepper motors, making them groan as they do their work. hear it for yourself in the test video after the break were the machine is first tested as a pen plotter.

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Hackerspace Intro: TkkrLab in Enschede, Netherlands

[Dave Borghuis] put together a quick video tour of the TkkrLab hackerspace in the Netherlands.

The tour stats off with the entry system. We looked in on this project at the end of last year. The space totals about 150 square meters (about 1600 square feet) divided into three rooms. There’s a ‘dirt’ room which houses some tools for woodworking and general fabrications. Another room is used for electronics prototyping, including a 3D printer and CNC mill. Finally there’s the large meeting room which acts a hang-out lounge to work on your projects, watch some movies, or hold events.

There are weekly meetings on Tuesday nights which are open to everyone. There’s also a range of classes given covering topics like learning Python, or an intro to Arduino.

We really enjoy seeing these tours. What are you waiting for? Send us a video tour of your own hackerspace!

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Golden spiral chicken coop

[Marchelo] wanted to build his own chicken coop. He started researching different designs and ended up basing his build on the golden spiral.

In addition to the interesting shape, a ton of clever design choice made it into the build. For instance, [Marchello] took the time to dramatically round over the lumber used as the skids of the base. This, along with wheels on one side, will make it much easier to slide the coop if he needs to move it. Also, the roosting boxes are an addition to the side wall of the hen-house. The roof for these boxes is hinged, so checking on the chickens, or harvesting eggs happens at a comfortable height for the farmer. And finally, the plank that allows entry for the hens doubles as the door at night. So far this is a manual-operation, but we could see some mechanization as a future improvement.

[via Reddit]

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