Micro Audio Player Can Hide Behind A Postage Stamp

March 5, 2011 by Mike Nathan 28 Comments

The original iPod shuffle was a pretty small device, there’s no doubt about that. However, in the world of miniature audio players, [Chan] is no slouch either.

A few years ago, he set out to construct a micro audio player that used little more than a small microcontroller and a microSD memory card. He chose an ATinyX5 series microcontroller to run the show, utilizing its pair of PWM output pins to directly drive the speakers. Since there is no built-in amplifier, the audio volume is not loud, but it does sound reasonable if you use a set of high efficiency desktop speakers. He does mention that the sound can easily be amplified after passing the signal through a filter, so there is hope for those of you who like your music turned up to 11.

The only downside we can see is that the audio player can only process Wave files, but it’s hard to expect more from a DIY audio player smaller than a postage stamp. It would be great to see what sort of micro-handiwork [Chan] could perform if he were to update his design and build a full-functioning MP3 player based upon this project.

Bluetooth-enabled Talking Chicken

February 28, 2011 by Mike Nathan 4 Comments

bluetooth_chicken

[Jeri Ellsworth] sent us a video walkthrough of a hack she did a few years ago using a toy chicken with a motor operated mouth. She wired up a Bluetooth headset’s audio output to a LM386 audio amplifier, which drives the speaker she added to the chicken. The output of the audio amplifier was also connected to a 555 timer in bistable mode to activate the motorized mouth. The motor simply opens the mouth when activated, allowing the built-in spring to snap it shut when the 555 is reset.

Obviously Jeri didn’t send us an old project just for kicks, she wanted to remind all of our readers that the 555 Design Contest comes to a close tomorrow night, March 1st at 11:59 EST. If you haven’t submitted an entry yet, get something started while there is still time!

Keep reading to see Jeri give a quick video overview of her talking Bluetooth chicken.

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A Trio Of Last-minute 555 Timer Projects

February 28, 2011 by Mike Nathan 5 Comments

[Bob] has been busy lately putting the finishing touches on three different projects that he plans on entering into the 555 Design Contest.

His first entry is a low-power H-bridge, which can be used to drive small servos. While he admits that it is a bit odd to build use a 555 timer to construct an H-bridge, they are cheap and plentiful enough to justify their use. Check out the video below to see the simple H-bridge controlling a servo.

[Bob’s] second entry is quite a bit more complex than his H-bridge. His secret knock detector listens for a pattern of knocks, triggering a relay if the proper cadence is detected. If a knock is heard, the first 555 timer starts, listening for another knock within a specific time range. If a knock is heard during this period, the next timer is triggered, and the process is repeated. Subsequent knocks must be timed correctly, or the circuit halts, waiting for a reset timer to expire before listening is resumed. It’s a bit hard to get the knocks just right, but that should be fixable with a few small tweaks.

The third entry he sent us is a project that is pretty common, though with a somewhat uncommon implementation. Class D amplifiers are often built as low-power headphone amps for personal audio applications. He liked the idea of a Class D amplifier, but wanted to build something with enough power to listen to his music in a small room. To accomplish this task, he looked over the internal block schematics of a 555 timer and constructed a pair of high-power 555 timers himself, using discrete components to mimic those usually found in the 555 package. His results were decent, though admittedly not of the highest quality, and could be tweaked a bit to provide better sound fidelity.

Continue reading to see videos of each project in action.

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Fabric Speaker

February 28, 2011 by Mike Szczys 20 Comments

The theory behind speaker operation is pretty simple. There’s a coil that is attached to some type of diaphragm and a permanent magnet. When electrical signals pass through the coil a magnetic field is generated, and that field’s interaction with the permanent magnet causes the diaphragm to vibrate and create sound. But we’ve always assumed that the vibrating material must be stretched tight for this to work. [Hannah Perner-Wilson] proved us wrong by making this speaker out of fabric. It uses conductive tape as the coil on a heavy piece of canvas. The permanent magnet is resting on a table and for the demonstration the fabric is just laid on top.

Check out the video after the break to hear the sounds generated by this device as well as a design that uses conductive thread instead of tape. This gets us wondering if what we’re hearing is the result of the magnet vibrating against the tabletop? Let us know your thoughts, and if you’ve got any information about the paper-backed circuit (seen at 0:04 into the video) driving the speakers we’d love to hear about that too.

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Light Sensitive MIDI Glove

February 22, 2011 by Mike Szczys 3 Comments

The latest offering in glove-based noisemakers forsakes commonly used flex sensors in favor or photoresistors. [Bruno Ratnieks] is responsible for this musical glove and his methods will be very easy to recreate. He used an Arduino to interface with it while providing a USB connection to your audio software. The sensors themselves couldn’t be easier to throw together, with each photoresistor creating a voltage divider when combined with a fixed-value resistor. That’s all the hardware you need, and with some creative coding you can making it do much more than the effects heard in the video after the break.

Some will say that [Bruno] simply didn’t used enough duct tape with his project design. Be we liked how he wove the wiring into the mesh of these knit gloves to keep it firmly in place.

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8-bit MIDI Synthesizer

February 18, 2011 by Mike Szczys 14 Comments

[Derek Enos’] toils are starting to yield results. He’s been working on an 8-bit synthesizer that is MIDI controlled which he calls the deMIDulator. As he demonstrates after the break, the device has sine and square wave functions that produce quite a pleasing sound. But it also offers the option to record your own samples which are then modified based on the MIDI commands coming in from your device of choice. In this case he’s using a Rock Band 3 keyboard (or keytar if you will) in a much more creative way than its originally intended purpose.

For now we’ll have to be content with the demo video and a list of features as there are no other details. But open sourcing the code and hardware information are on his to-do list. Continue reading “8-bit MIDI Synthesizer” →

Uncrippling Lower Model Speakers

February 12, 2011 by Mike Szczys 89 Comments

It looks like this low-end Sennheiser HD speaker has the same internals as it’s better-brother but has been altered to reduce sound quality. It’s not uncommon for manufacturers to hobble a product in order to sell more units at a lower price that reflects less features. Linksys WRT54G routers immediately come to mind, or perhaps the more recent Rigol 100 MHz oscilloscope hack is a better example.

In this case, that black piece of foam on the left has been added to the 555 version of the hardware to decrease the sound quality you get from the much more expensive 595 model. Take it out and you’ve got an upgrade that would have cost you more than a hundred bucks. Don’t think this is the only difference? There is a bit of a difference in case design, but [Mike Beauchamp] also found that if you acquire a replacement driver for either model you’ll get the same part.