

Demonstrating an unusual application of a CMOS NOR gate to implement a CMOS varactor controlled VCO, I explore the idea of circuit schematics as a music notation and how scholars and practitioners might create and analyze notations as part of the rich web of interactions that constitute current music practice.
The following pages provide context for the workshop and include links to contributions from my co-teacher, Martin De Bie. This includes pointers to various iterations of his 555 timer-based Textilo project.
This project will be expanded ongoingly with further relaxation oscillator schemes.
This style is not convenient for eTextile Appliqués which are most commonly single-sided and are based on cut traces rather than etched boards.
There is an older style of PCB layout that is more suitable for low-speed e-textiles that I remember seeing with old transistor radios. The style is almost all copper with just a few lines etched away to separate conductors.
This makes designs more robust with multiple parts soldered on and removed and with multiple sewing points at the edges.
It also makes for less weeding and more surface area that will be fused/glued to the base fabric.
It was also common for many of the traces in these radios to be curved.
For the eTextile Spring Break I guided Martin De Bie through some iterations of his original Textilo design that includes this new thinking on layout and a further insight regarding the 8-pin DIP packages commonly used now by eTextile electronics experiments (with the ATTINY and 555 timer being common choices). This insight is to start the design from the DIP package and imagine the negative space of the smallest amount of conductive fabric that needs to be weeded to separate the 8 pins and combine the constraint of roughly equal area given to the conductors attached to each pin. This results in a motif with 8 radial lines and 8 triangles between them.
Here is the original textilo with its elegant pads to sew to:
Here is the next version with more conductive material to work with alongside the prototype of a radial design. The radial design includes serpentine interdigitation to allow for touch interaction:
Nicole Yi Messier picked up on this radial design pattern for her wearable 555 timer based FM radio transmitter:
Approach | Example | Link |
---|---|---|
non-electronic | Lamello | http://bid.berkeley.edu/papers/chi/lamello_passive_acoustic_sensi/ |
*Analog relaxation oscillator | Textilo | http://www.martindebie.com/research_project/textilo/ |
Analog harmonic oscillator | self-resonating VCF | http://electronotes.netfirms.com/EN215.pdf |
*Digital relaxation oscillator | Arduino Tone | https://github.com/adrianfreed/FastTouch |
*Digital relaxation oscillator | Mozzi (LUT) | https://github.com/sensorium/Mozzi/blob/master/examples/01.Basics/Sinewa... |
*Digital Modulation Synthesis | Mozzi (FM) | https://github.com/sensorium/Mozzi/tree/master/examples/06.Synthesis/FMs... |
*Digital Subtractive Synthesis | Talkie (LPC Speech and singing) |
https://github.com/adrianfreed/Talkie |
Unit Generator Library | Teensy Audio Library | https://www.pjrc.com/teensy/td_libs_Audio.html |
Sampling "Synthesis" | Tone.js (Tone.Player) | https://tonejs.github.io |
Dynamically Patched Unit Generators | Bela (libpd) | https://bela.io |
Dynamically Patched Unit Generators with Image Synthesis |
Max/MSP/Jitter | https://cycling74.com/products/max |
Analog Patched Modular | Modular | https://en.wikipedia.org/wiki/Modular_synthesizer |
I discovered by accident that some folk from Greece published the same ideas in a professional technical journal in 1989 (attached). If you are a scholar of such things it is interesting to compare and contrast the modes of articulation in my vernacular engineering approach with those of the academic paper.
As I review this design from the 1970's I am struck by the exotic mixture of TTL/CMOS logic/CMOS switches, transistors and opamps that were required to pull it off. Although it might seem that such techniques are obsolete, I have seen plenty of recent Arduino designs using resistor networks that have faced the same challenge of creating a function with positive and negative values from binary sources.
Q: How would I do it differently today? A: I would replace the 555 timer and TTL parts for an Arduino and use a rail to rail inverting opamp.
Interestingly the parts required are all still available and the Arduino solution would cost about the same. The main cost difference would probably be from the the two-pole multiway switches which are expensive these days.