A 16 bit DAC solution for your Arduino! The schematic is very simple, it's just the DAC (Analog Devices AD420), a few capacitors and an operational amplifier used as voltage follower in order to provide some buffering to the DAC output. The DAC is not very cheap (around 15-18$!) but it allows to obtain a good resolution in order to satisfy all your accuracy needs... I've built the circuit using a smd-to-dil pcb adapter, but the DAC is also available in a breadboard-friendly PDIP package.

arduinOSC is a library which transforms your arduino into a simple arbitrary waveform audio oscillator.
It is based upon the internal 16-bit programmable timer and generates audio using pulse width modulation (PWM) and an external low-pass filter (square waves don't even need the external filter).
I'm using a simple passive low-pass filter, but in the next days I'll try an active low-pass filter based solution.
The library includes a sine wave lookup table (LUT) and a user-definable lookup table which can be found in the file named "user_waveform.h" under arduinOSC folder: if you whish to change this waveform just edit the file and then delete "arduinOSC.o", so the next time you will compile your sketch the library will be rebuilt.
Square waves are generated without a LUT, and in the next version also triangle, ascending sawtooth and descending sawtooth will be generated in this way, so the LUT will be used just for sine and user defined waveforms.
So far the library has been tested with Arduino Nano and Arduino Diecimila with the new ATMega328P.

A minimal MIDI input/ouput board ready to be connected to your Arduino! The schematic is very simple, I used a single-copper-hole prototyping board to build mine, but a breadboard is also a nice alternative.
Basic MIDI output is really easy to do with Arduino, all you have to do is initialize the serial port using Serial.begin(31250), then you can send standard MIDI data using Serial.print function.
If you don't want to mess too much with low level MIDI data handling you can just use the MIDI Library developed by François Best, otherwise just read the MIDI protocol specification and start doing your experiments!

Yesterday evening I came back from work and turned on my PC, but instead of seeing the usual windows loading screen, an horrible "Insert a bootable media" warned me that my 2-months old 500gb hard disk was somehow fucked up...
The first thing I thought was that the MBR was damaged, so I tried to boot from a Knoppix Live CD to see if there was a way to access the hard disk content, at least. Then I noticed that the BIOS wasn't even detecting the hard disk, and it took more time than usual to scan the IDE/SATA devices.
I started a search on google to see if somebody already faced this problem, and found several posts, on Seagate/Maxtor forums, talking about a bad firmware on some models produced in 2008 (only the ones produced in Thailand, as far as I can see) that could lead the drive to hang in a busy state (forever!) after a reboot.

Last night I was working on my sequencer project and, looking at the sensors I recently bought from SparkFun, I had this nasty idea... so i wired up the MQ-3 alcohol sensor, hooked a 200k trimmer to it just to calibrate the range of the measures, and voilà! The sequencer global shuffle can now be controlled using your breath alcohol content...

Some days ago I received my first Lilypad Arduino and started to experiment with a SMD Bluetooth module i bought from Sparkfun. The connection between the BT module and the Arduino board has been described here by Leah Buechley, but instead of using a BlueSmirf Gold Board (which is based upon a Roving Networks module and costs more than 60$) I tried the less expensive Sparkfun SMD module.
From a software point of view, the only difference is the command set when the module is in COMMAND mode.

First of all I covered the back side of my Lilypad Arduino with a layer of insulating pvc tape, then, using a small piece of biadhesive tape, I secured the Bluetooth module over the pvc tape.
The connections are quite easy as you may notice from the picture, the only detail that's worth a mention is the small 2 way smd dip switch between the crossed RX/TX connection to Arduino pins, in order to disable the module communication with the ATMega chip when using the USB programmer to load a sketch, since with Lilypad standard bootloader it's not possible to load sketches via Bluetooth.