Camera Trick Lets You See Sound Waves In Falling Water

March 14, 2013 by Mike Szczys 27 Comments

From this still image you’d think the hose dispensing the water is being moved back and forth. But watch the video after the break and you’ll see the hose is quite steady, as is the standing wave of water. It’s bizarre to be sure. Knowing how it works makes cognitive sense, but doesn’t really diminish the novelty of the demonstration.

This is the second time [Brasspup] has posted a video of this phenomenon. The newest version does a great job of showing several different patterns. But even the first segment from a year ago, which has over 4 million hits, shows the water moving against gravity. We also saw a similar rig in a links post a year ago.

We’d call it an optical illusion but it’s really more of a technological illusion. The water is falling past a sub-woofer speaker which is tuned to 24 Hz. At the same time, the camera filming the demonstration is capturing 24 frames per second. As was mentioned then, it’s much like flashing a light to freeze the water in mid-air. But the flashing of the frames is what causes this effect.

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Raspberry Pi As A Spotify Server With MPD Control

March 14, 2013 by Mike Szczys 15 Comments

The Raspberry Pi has been very popular as a streaming music player. Sure, the only audio out option on the board is an analog stereo jack, but you can use a USB audio device to improve upon that if you wish. [Wouter van Wijk] wanted to use his RPi as a Spotify server. It’s a bit tricky to get everything configured for this, so he decided to give back by publishing a ready to use Spotify server image for the Raspberry Pi.

The project is call the Pi MusicBox. Like some of the RPi Pandora setups we’ve seen he included the ability to use the hardware as an AirPlay device too. To connect to the Spotify service he uses the Mopidy package. It can also play tracks from local storage (including the home network). It’s even capable of mixing the two sources in the same queue. Possibly the best part is that it can be controlled with any Music Player Daemon (MPD) client like the smart phone screenshots seen above.

If you’re interested, check out his GitHub repo for the project.

No-touch Music Player

March 13, 2013 by Mike Szczys 10 Comments

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This little box not only plays tunes, but it lets you control several aspects of playback without touching a thing. [Thomas Clauser] calls it the LighTouch and we like it because it uses inaudible sound to control audible sound.

We think the pair of cylinders sticking up through the top of this project enclosure will be recognized by most readers as the business end of an ultrasonic rangefinder. This is the only control interface which [Thomas] chose to use. Although he didn’t write very extensively about the specific control scheme he implemented, the video embedded in his post shows some of the gestures that cause the Arduino inside to change its behavior. For instance, a swipe of the hand at higher level starts playback, swiping at a lower level pauses it. When adjusting the volume the box responds to how close his hand is to that sensor. With this control in place, the music side of these things is simply handled by a music shield he is using.

Hacked Auxiliary Port For A Car Stereo

February 19, 2013 by Mike Szczys 29 Comments

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We’re not sure if [Apachem25] is just lucky, or if installing Auxiliary ports on most car stereos is this easy. The dealership wanted $95 to put one in, but he managed to add a 3.5mm audio-in port to his car stereo for just a couple of bucks.

The connector on the back of his head unit is a 2×4 set of pins recessed in a protective plastic ring. It turns out that the audio connector cable for a PC CD-ROM drive has a 1×4 socket that is perfect for this. [Apachem25] simply clipped one of those cables in half and used both ends to interface with the Aux port. He found the pin-out for his particular model on the Internet. He needed a specific resistance value between two of the pins to get the deck to let him use the input. All that he needed was a quick bit of soldering. The left, right, and ground are brought around the side and soldered to an audio jack he added in the face plate of the unit.

If you’re still rockin’ the cassette deck our favorite automotive Bluetooth solution is still this one for a classic Beetle.

[via Reddit]

Building An Inexpensive Squeezebox Client Replacement

January 11, 2013 by Mike Szczys 20 Comments

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[Andrew] is a fan of the audio quality provided by the Squeezebox hardware. Like many he was unhappy to hear that the devices were being discontinued, but he figured out a way to build a Squeezebox client clone for less than he could have bought an original.

He set several goals for the build. Most notably he wanted the system to be low-power, noiseless, and to support audio quality of at least 96 kHz at 24 bits. What he came up with is the Pogoplug seen in between the two speakers above. It can be acquired for under $20 and it runs embedded Linux. Another member of the Squeezebox community had been working on a custom distro called SqueezePlug to turn these types of devices into Squeezebox clients. After flashing the distro and tweaking the settings [Andrew] has accomplished his goals. The one caveat is the lack of an audio out port. Above he’s using some cheap USB speakers, but higher-fidelity is possible by choosing a more expensive external USB device.

This will work nicely with that Squeezebox server you built from a Raspberry Pi.

Adding AirPlay To A Shelf System

January 8, 2013 by Mike Szczys 27 Comments

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AirPlay is a great system. It allows you to send whatever media is playing from one device to another. Sure, we wish it were a bit more open (Apple is certainly not known for that) but there are several option for creating your own AirPlay receivers. After coming across a project that does just that, [Matt Shirley] decided to turn his shelf system into an AirPlay receiver.

The path to his goal depends on the Raspberry Pi’s ability to receive AirPlay audio using the Shairport package (we just looked in on another player that does this last week). He uses an Edirol UA-5 USB audio interface as an amplifier for his record player. He wasn’t using the USB port for it and knew that it would be simple to connect the RPi USB as a host for the device.

Wanting to keep the look of the system as clean as possible he popped the lid off of the amp. There is just enough room to fit the small RPi board inside. He hacked (literally, look at the pictures) an opening for the USB ports into the side of the metal enclosure. A short patch cable connects from one port to the USB jack on the back of the amplifier. The white cable leaving the side of the case provides power to the Rasperry Pi. The surgery was a success and now he can listen to his tunes with a tap of his finger.

Ice Record Single Needs Six Hours In The Deep Freeze Before You Can Listen

December 31, 2012 by Mike Szczys 36 Comments

ice-record

This delightful marketing ploy requires the listener to fabricate their own record out of ice. The band Shout Out Louds wanted to make a splash with their newest single. So they figured out how to make a playable record out of ice. The main problem with this is the grooves start to degrade immediately when the ice begins to melt. So they shipped a mold of the record and a bottle of water to a select few listeners (just ten in all). Hear the result in the video after the break.

Now if you want to make something like this for yourself we can help you out just a bit. The mold is made of silicone and it wasn’t so long ago that we saw a guide for those new to mold making. The raw material isn’t that hard to find either. The project above tried several different approaches and found the best results can be attained with plain old distilled water. No, the one hard part is figuring out how to make your own master. If you’ve got a way of doing this in the home lab, please tells us about it!

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