Auduino: DIY Arduino Synthesizer
March 6th, 2010 
Art, FabLab, Physical Computing, Video 
Mark Kizelshteyn
My first physical computing project is complete! The Auduino: A DIY synthesizer.
Auduino: DIY Arduino Synthesizer from Mark Kizelshteyn on Vimeo.
A fantastic project by the tinker.it (Arduino) team, and I highly recommend it to anyone who is interested in getting into electronics, using Arduino or just wants to build a synth. All code, designs and schematics are open under Creative Commons Attribution-Noncommercial License. All files (designs, code et cetera) I used/made can be downloaded below.
A friend showed me his Auduino, and I needed to build one too! I decided to make a few modifications to the original. I added a switch that enables a light dependent resistor (LDR) to control the rate of the noise, which essentially means the more light that hits the resistor, the faster the tempo. When the switch is on, it disables the associated potentiometer and enables the LDR. It’s a fun addition and you get the chance to put your whole body (or just hand) into the synth.
I also did not want to commit to one mapping of the Auduino — I liked both the the smooth frequency and the stepped pentatonic mapping, so I added a switch to move between the two synthesiser parameters.
Section of edited code:
if (digitalRead(SWITCH)) {
// Smooth frequency mapping
//syncPhaseInc = mapPhaseInc(analogRead(SYNC_CONTROL)) / 4;
// Stepped mapping to MIDI notes: C, Db, D, Eb, E, F...
syncPhaseInc = mapMidi(analogRead(SYNC_CONTROL));
}
else {
// Stepped pentatonic mapping: D, E, G, A, B
syncPhaseInc = mapPentatonic(analogRead(SYNC_CONTROL));
}
This is the schematic for the way I wired my Auduino. I used Fritzing software, which is also a great beginner tool for prototyping your circuit board. Fritzing is a neat open source project, I recommend checking them out.
Lastly, I needed to design an enclosure, which was also a first. Inspired by enclosure extraordinaire, Xander (see his work at machinecollective.org), I designed a simple yet functional enclosure in Illustrator and cut it using a laser cutter. After two failed enclosures, the third one fit! I initially wanted to have it enclosed in black satin acrylic, but I ended up with a transparent enclosure so I could see the components. In retrospect, I should have stuck with the black as the transparency detracts from the minimilist aesthetic I sought. I have attached my designs here — feel free to use/modify (CC license).
How does it work?
Tinker.it explains: “Sound is generated by playing the same noise (‘grain’) repeatedly at very high speed. This merges into a tone that is an audible hybrid of the repetition rate and the original grain. It sounds quite similar to an oscillator with two resonating bandpass filters, although the different architecture means there are lots of additional interesting noises at parameter extremes. The grain consists of two triangular waves of adjustable frequency, and adjustable decay rate. This is based on FOF synthesis model, but using triangle waves instead of sine and using a rectangular window. The repetition rate is set by another control.”
Build one too! After spending the last few months at the CabFabLab, I have been become enamored by physical computing, and I have been reading makezine fairly religiously now. If you are just getting into this world, like me, it is a fun blog to read.
Resources:
- The Google group that details the project here.
- My minor edit to the code can be found here.
- My illustrator designs can be found here.
- My Fritzing file (schematic details) can be found here.
Tags: Arduino, Auduino, DIY, FabLab, Synthesizer
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