Computer Musician, Programmer, Hardware Hacker

A simple comb filter with modulation – makes strange phasey, pitch-bendy sounds.

Patch: 2_comb.maxpat

I’ve spent the last day or two building a Ciat-Lonbarde ‘Lil Sidrassi’ – a noise-maker/instrument built on a paper circuit. I was attracted to the visual layout of the circuit, as well as the environmentally friendly and affordable paper circuit board. I often worry about the environmental footprint of factory-produced PCBs, and the working conditions in the Chinese factories where they are produced. I think Ciat-Lonbarde is onto something good with their circuits, and I wonder how they would scale to more complex and/or microcontroller-based circuits… I know they produce more complex instruments, but they seem to use SMD devices and commercial PCBs in those.

Lil Sidrassi

The ‘Lil Sidrassi’ is a very performative and tangible instrument. Here’s the circuit/assembly manual/schematic – print it out and hang it on the wall.

The upper part of the circuit is a ring of 5 coupled transistor-based oscillators. Each oscillator sources current for the next one in the ring. The cross-shaped pads are connections for wires, which are meant to be soldered to contacts. I used 11 wood screws as contacts, and installed the device into a black plastic project box. (Eventually I want to mount it more permanently in a nice wooden box, but this will do for now.) By touching the contacts with her hands, the performer reorganizes – ‘bends’, if you must – the circuit, connecting various parts of the oscillator ring together. The capacitor values which determine oscillator frequency are considered ‘hairy capacitors’ – meaning they can be of any value. I went for the so-called ‘chaotic’ configuration, using clockwise decreasing capacitor values. You can also bridge touch the circuit itself – a 9V battery won’t kill you – to produce even more dramatic effects.

A further possibility would be to build a few of these and ‘patch’ them together using alligator clips or your hands.

The lower part of the circuit is an LM386-based audio amplifier and power circuit with some filtering caps and a diode. There are pads for a speaker/1/4″ jack output and a 9V battery supply.

Here’s a video demonstration of some of the sonic capabilities.

And here’s what it looks like on a scope – clearly very noisy and dynamic. The exponentially-decreasing sawtooth pulses are generated by the capacitors as they discharge.

There’s more on the circuit – and some others – at http://www.ciat-lonbarde.net/ 

Here are two new tabulaRasa demos:

From Clarke Robinson (who designed the panel in the video), using a set of vocal waveforms, no effects:

From Greg Davis, using tables composed of mixed harmonically-related sinusoids, through a filter, and a delay:

Here’s a demo of some software I developed for Tom Erbe’s music software development course at UCSD. The program allows you to generate modular synth control voltages using a standard AC-coupled audio interface. A diode and capacitor are the only required external hardware. The program is written in C++ using the Qt framework. Download the source, documentation and OS X binary here.

This is a demonstration of the USB -> CV PC/Analog Synthesizer interface I’m developing.

In this clip, sample data is being sent from Max/MSP over the serial port to a Teensy 2.0 microcontroller. The controller sends the incoming data over an ISP connection to a DAC, the output of which can be used as a modulation source for analog synthesis modules.

Computer Generated Control Voltage Generator from Greg Surges on Vimeo.