Acoustic levitation of water droplets

acoustic-levitation-water-droplets

These water droplets are not falling; they’re actually stuck in place. What we’re seeing is the effects of an acoustic levitator. The device was initially developed by NASA to simulate microgravity. Now it’s being used by the pharmaceutical industry do develop better drugs.

The two parts of the apparatus seen in the image above are both speakers. They put out a sound at about 22 kHz, which is beyond the human range of hearing. When precisely aligned they interfere with each other and create a standing wave. The droplets are trapped in the nodes of that wave.

So are these guys just playing around with the fancy lab equipment? Nope. The levitation is being used to evaporate water from a drug without the substance touching the sides of a container. This prevents the formation of crystals in the solution. But we like it for the novelty and would love to see someone put one of these together in their home workshop.

Don’t miss the mystical demo in the clip after the break.

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Simple hack plays any sound as your door chime

[Jim’s] technique for turning a wireless doorbell into a custom ringtone player is so simple. He manages to get the entire thing done using only a screwdriver and wire clippers as tools. But if you’re looking to use this over the long-term we’d recommend soldering the connections rather than relying only on the twisted wires.

Above you can see all the components used in the project. The wireless doorbell unit is no different from most battery-operated units on the market today. Inside the Radio Shack box is a recording module that lets you play up to 20 seconds of audio. This is powered by the 9V battery on the right. [Jim] removes the speaker from the doorbell and clips off one of the wires that connected it to the board. This is reused as the ground connection for the recording module. The other speaker wire is connected to the ‘Play’ button on the module’s PCB. That’s it, just record your custom sound and pack everything back into the doorbell’s case. You can see the entire hack and hear a demonstration after the break.

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Doppler-effect lets you add gestures to your computer

What if you could add gesture recognition to your computer without making any hardware changes? This research project seeks to use computer microphone and speakers to recognize hand gestures. Audio is played over the speakers, with the input from the microphone processed to detect Doppler shift. In this way it can detect your hand movements (or movement of any object that reflects sound).

The sound output is in a range of 22-80 kHz which is not audible to our ears. It does make us wonder if widespread use of this will drive the pet population crazy, or reroute migration paths of wildlife, but that’s research for another day. The system can even be used while audible sounds are also being played, so you don’t lose the ability to listen to music or watch video.

The screen above shows the raw output of the application. But in the video after the break you can see some possible uses. It works for scrolling pages, double-clicking (or double-tapping as it were), and there’s a function that detects the user walking away from the computer and locks the screen automatically.

[Sidhant Gupta] is the researcher who put the video together. In addition to this project (called SoundWave) he’s got several other interesting alternative-input projects on his research page. Continue reading “Doppler-effect lets you add gestures to your computer”

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.

chipKIT Sketch: Mini Polyphonic Sampling Synth

In our hands-on review of the Digilent chipKIT Uno32, we posed the question of what the lasting appeal might be for a 32-bit Arduino work-alike. We felt it needed some novel applications exploiting its special features…not just the same old Arduino sketches with MOAR BITS. After the fractal demo, we’ve hit upon something unique and fun…

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Crash Space Takes on the Machine

It’s that time again, time to take on the machine with the Hackerspace, Crash Space (and part two)! The team of Californians set out and successfully turned the front of their building into a musical instrument, similar to [David Byrne’s] Playing the Building. When a pedestrian walks by they set off distance sensors, which in turn actuate mallets that strike particular objects to produce a tone. We were pleasantly surprised at how interactive the installation was, even if it didn’t sound that great. But will it be enough to beat out the previous two teams? And how will it do up against Artisans Asylum’s not what you’re thinking Breakfast Machine next time?

[thanks Deven]

5 Tones, 1 Arduino

Because the Arduino is in such high demand for producing multiple musical tones at the same time; [Jeremy Blum] has successfully figured out the math and other necessaries that will take your once previously single tone producing MCU and turn it into a 5 tone producing machine. unsurprisingly its really just some creative use of PWM control but it all works out in the end anyway and helps prevent you from purchasing additional sound generating chips. This truly does open up some new doors, as [Jeremy] shows with his still in production thingamakit like project: ReacXion.