Fifty dollars to make your car audio Bluetooth compatible

We’re rather impressed with the work [Aaron] did to add Bluetooth connectivity to his 2008 Honda. He used an aftermarket kit, but rolled in his own revisions to make it look and feel like an original feature.

After being disappointed by an expensive docking system he grabbed a Jensen BT360 kit for about $35. It comes with an external speaker which would look horrid mounted on the dash. That speaker is meant to play your telephone audio via Bluetooth, while music from the phone is sent to the car stereo using an FM transmitter. Since he planned on hiding the control unit under the dash anyway, it wasn’t too hard to add some wires which intercept the audio being fed to that FM transmitter. From there he added a couple of relays to automatically route the audio signals (when present) and patched the whole thing into the Aux input. This way he doesn’t need the extra speaker, and all sound is feed to the head unit via wire instead of radio transmissions.

The final setup works pretty well. If a phone call comes in it automatically mutes the volume, or pauses the iPod if that’s what’s currently playing through the Aux port. [Aaron] thinks the bass from music played via Bluetooth is not quite as rich as when using the Aux port, but if you don’t mind the cables that’s still an option too.

Building a media player with an MSP430

A media player based on an Arduino and SD card has been done to death several times over, but that doesn’t mean we can’t appreciate [Matt]’s MSP430 audio player. It’s a very nice piece of work that supports a FAT16 file system and only takes up 54 bytes of RAM.

To make his dream of a 430 media player a reality, [Matt] based his work on the DIY Life Talking MSP430 project. Unlike this previous attempt to play music with a ‘430 and SD card, [Matt] threw in a full FAT16 file system, allowing him to drag and drop audio files on his computer to the SD card.

Right now [Matt]’s build can play a stereo audio file through its speakers, but the sound quality over a mono file is greatly reduced. The maximum sample rate is 16kHz; a ‘good enough’ sample rate if you’re listening with terrible headphones. In the video after the break, [Matt] plays this awesome Symphony of Science on his homebrew media player. We’re guessing his camera doesn’t do his project justice, but it’s still impressive nonetheless.

[Read more…]

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. [Read more…]

RFID playlists plus a QR code concept

Here’s another audio playback hack that uses physical tokens to choose what you’re listening to. It uses Touchatag RFID hardware to control iTunes. The concept is very similar to the standalone Arduino jukebox we saw on Wednesday except this one interfaces with your computer and the tags select entire albums instead of just one song. A shell script processes the incoming tag ID from the reader, populates a playlist with all the tracks from the associated album, then executes an AppleScript to launch that playlist. Check out the short demo after the break.

But what really caught our eye is the QR-code reader concept which [Janis] hopes to implement at some point in the future. The computer side of things doesn’t need to be changed, but we love the challenge of putting together an FPGA-based camera to recognize and decode the QR image. Looks like a perfect use for that $10 camera module and it’s FPGA driver!

[Read more…]

RFID jukebox for the kids

[Dominik] built a fun musical toy for his daughter [Anna]. It’s a jukebox that lets her play her favorite tunes using RFID tags to select between them.

The project is simple, yet robust. The enclosure is a wooden craft box that you can pick up for a couple of bucks. Inside there’s an Arduino with a Wave Shield which handles the audio playback. An RFID reader takes input from the set of card-tags he procured. An internal Lithium battery powers the device, with a USB port for charging.

Sure, those guts have some cost involved in them. But there’s no LCD which can be broken, and we thing the boards will hold up well to abuse if mounted correctly. Plus there’s a lot of future potential here. When we saw the cards we thought of those toys which make the animal sounds (“what does the cow say… mooo”). This could be used for that with really young children. Then repurposed into this jukebox as they get a bit older. If you put the guts in a new enclosure it will appear to be a brand-new toy, right?

See a demo of the project in the clip after the break.

[Read more…]

From reference design to USB sound card

[Entropia] decided to try his hand at rolling is own sound card. He picked out a DAC chip, started his prototyping by studying the reference design from the datasheet, then went through several iterations to arrive at this working model.

He chose to base the board around the PCM2706. It’s a digital to analog converter that has built-in USB support; perfect for his needs. It’s got a headphone amplifier, but is also capable of putting out S/PDIF signals for a digital amplifier to pick up and use. Not bad for a part that can be had for right around eight bucks.

The first PCB he designed had a few electrical and footprint errors. But he was able to get it to run by adding some point-to-point jumpers, and bending the legs of his capacitors to fit the board area. With those issued accounted for he ordered a second batch of boards. These went together nicely, but the headphone output was incredibly loud. Turns out the filtering circuit had the wrong resistor and capacitor values. Changing them around, and swapping the audio output so that the correct channels were patched to the audio jack brings it to the first release version seen above.