• 1/4" Jack Of All Trades

Physical Computing Week 4 - Touch Sensors and Final Project Proposal

Updated: Nov 29, 2020

Lab 1: Servo

Lab 2: Motor

Lab 3: Capacitive Touch Sensor

Lab videos will be added soon.

Final Project Proposal (in more detail than slides):

Predictably I want to create a noise making device for my final project. So I have decided to make a synthesizer. Native capabilities of the Arduino are very limited for making sound beyond an irritating square wave... I get more interesting timbres from my induction hob. However, I have discovered several libraries for adding more complex synthesis capabilities to the Arduino, most intresting is the Mozzi library.

The output components really just choose themselves: an audio out (ideally I want a 1/4" jack out) and LEDs. In terms of input device there will obviously be plenty of potentiometers (mix of knobs and sliders) but I have also been considering the use of a capacitive touch sensor to create a sort of keyboard with more nuanced interaction than simple buttons, more on that later. Other options include a ribbon controller, something I fell in love with while playing around with an old Moog modular synth, and a joystick to use as an X/Y controller - one with a clicker function could be handy for cycling through potential functions of the controller (with LED feedback to know which option was currently selected)

Side note: as I have access to an Arduino Nano in additon to the Leonardo I was wondering if I could use both simultaneously with a slight pitch offset (perhaps user controllable) to create a thicker tone.


A big priorty for me is the ability to use microtonality, but at this point still undecided if I want it to be a drone machine or if it will take touch sensors as input devices. An advantage/opporunity that touch sensors affords is that I can try to address a problem that plagues microtonal music: the question of input device. The vast majority of MIDI/synth input is done via the traditional western keyboard (of varying sizes) but this is only really suitable for a 12TET tuning system. An 11TET tuning system for example changes keyboard layout on a traditional keyboard, as the octave is only divided up into 11 distinct tones.

There already exist some solutions (not many) to this problem, one such example being the Lumatone keyboard, however this is a very expensive solution. It has potentially given me the idea of using a colour coding system to make the user aware of the size of the octaves. With only having one touch sensor avalable (and of limited size) I may be forced to limit myself to TETs of 11 and under to avoid confusion.

Circuit Bending

I recently vented lockdown frustration on an old electro-acoustic guitar I found while clearing out the loft and from it was able to salvage the pickup and preamp with built in phaser. This got me thinking about trying to combine the practice of circuit bending with this project, even if it is just limited to adding circuitry from old guitars and guitar pedals into the output. The possibility of using an Arduino to send control signals to random bits of repurposed circuitry is quite a tempting prospect however, and is definitely something I will be exploring in the coming weeks.

Further Thoughts

Following the presentation of my idea to the rest of the class, I have also begun to consider taking a more sound art orientated approach. Inspired by this video, that was shown to another group also planning on making a synthesizer, I have started thinking about unqiue input systems for synthesis that challenge and fundamentally change the nature of performance. I think this 'sonic creature', as its creators describes it, looks very simillar to a spider plant and therefore I am considering if there is another kind of foliage that I can be inspired by. I have also thought about the potential of making a self influencing synth, perhaps using a feedback loop of light, sound and some moderate randomisation to make an organic feedback system.

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