RFID Jukebox For The Kids

March 14, 2012 by Mike Szczys 12 Comments

[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.

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From Reference Design To USB Sound Card

March 14, 2012 by Mike Szczys 17 Comments

[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.

Playing MP3s From An FPGA

March 13, 2012 by Mike Szczys 7 Comments

Building an audio player is a fun project. It used to be quite a task to do so, but these days the MP3 decoder chips are full-featured which means that if you know how to talk to other chips with a microcontroller you’ve got all the skills needed to pull off the project. But that must have been too easy for [Ultra-Embedded], he decided just to build an MP3 player out of an FPGA.

It’s not quite as difficult as it first sounds. He didn’t have to figure out how to decode the audio compressions. Instead he rolled the Helix MP3 decoder library into the project. It had already been optimized to run on an ARM processor, and since he’s using a RISC soft processor the translation wasn’t tough at all. He’s using a 24-bit stereo DAC chip to bridge the gap between the audio jack and the FPGA output. Clocking that chip with the FPGA isn’t ideal and causes 44.1 kHz audio to run 3% too slow. He says it’s not noticeable, which we believe. But if you try to play along with a song the pitch shift might end up driving you crazy.

If you’d prefer to just stick to the microcontroller based players this one’s small and inexpensive.

Tears From Your Lonely Heart Will Activate A Comforting Tune

February 14, 2012 by Mike Szczys 7 Comments

If you’re forever alone we’d guess you’ve long since stopped crying about it. But if you’re still prone to shed a tear on a dateless Valentine’s day this project’s for you. [Mikeasaurus] spruced up this pillow to play a tune when it senses your lonely soul. It’s got a moisture sensor which triggers an audio greeting card just when your weeping really starts to get soggy.

If you look closely at the top portion of the white fabric in the picture you can see there are rows of stitching. These hold a matrix of conductive wire mesh fabric on the inside of the pillow case. There are two buses made up of alternating rows (think of the tines of two forks pointed together) which make up the probes. When the gap is bridged by moisture a transistor circuit triggers the audio bits from a greeting card to play a song. Check out the demo after the break. We’re not satisfied that [Mikeasaurs’] couldn’t even bring himself to cry real tears for the clip, but maybe years of solder fumes have clogged up those tear ducts.

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Improving Headphones By Voiding Warranties

February 5, 2012 by Brian Benchoff 34 Comments

[Dan] had been wanting a pair of Bluetooth headphones for quite a while. Most of the reviews for wireless headphones in the $50-$80 range complained of tinny sound and dropped bass. Nevertheless, he stumbled upon a $20 pair of headphones with similar reviews and realized that he could switch out the driver and make a decent pair of cans.

The donor drivers came from a pair of Sennheiser HD 540 headphones. These are very respectable headphone speakers that cost about what you would expect for pro audio gear. To to get Bluetooth working with the Sennheisers, [Dan] removed the PCB and battery enclosure and attached them to the headband with velcro.

For his build, he had to cut the cable on the Sennheisers and solder them to the Bluetooth board. There was never any danger of ruining a good pair of headphones, though. If he screwed up he was only out a headphone cable. Now [Dan] has a nice pair of Bluetooth headphones that can reproduce bass. Not a bad deal for a $20 pair of headphones.

Rotary Phone-light-amp Could Be Filed Under Bizarre

January 25, 2012 by Mike Szczys 18 Comments

[Samimy’s] latest project is a little strange, but one man’s weird is another man’s wonderful so we’re not about to start criticizing his work. Nope, we’re here to praise the fact that his rotary phone turned reading light and audio amp is very well constructed.

He started by removing the phone housing. Those old enough to have used one of these devices will remember their bulk, and there’s a lot of unused space in both the handset and body housing. [Samimy] started by removing the speaker and microphone from the handset, and drilling a ring of holes to receive white LEDs. The circuit was wired so that lifting the handset turns on the lights.

But he didn’t stop there. A set of speakers and the audio amplifier circuitry from an old tape deck are also hiding inside the base of the phone. If you look closely in the image above you can see that he’s connected his cellphone and is listening to some tunes through the antique hardware. Take a gander at the video after the break to see construction and use of the project.

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NES Controller Cannibalized For MP3 Player Enclosure

January 19, 2012 by Mike Szczys 20 Comments

We know some folks are very upset by the scrapping on vintage hardware, so let’s all observe a moment of silence for this NES controller.

Now that that’s behind us we can live vicariously through [Burger King Diamond’s] project. He polished up the NES controller and repurposed it as an enclosure for a portable MP3 player.

His first step was to remove some of the yellowing of the plastic using Retr0brite. He admits it wasn’t bad to start with but now it’s sparkling like new. Next, he started planning how everything would fit in the case. Luckily the MP3 player operates with one AAA battery which leaves plenty of room.

Just above the A and B buttons you can make out an opening that he cut in the case for the MP3 player’s LCD screen. The bezel from the original case works well for cleaning the rough cut opening. The buttons on the controller have been patched into the controls on the MP3 board, and the opening for the controller’s cable now holds the headphone jack. There’s also a USB port mounted next to it for easy file transfers.

The one thing we would like to see is a rechargeable battery so you don’t need to open the case to top off the power. But all in all this is a fantastic build!