Analog Electronics

Conductive Paper Pressure Sensor and Arduino Teensy

Overhand knot in a strip of carbon-loaded paper becomes an FSR that can be easily connected to your favorite microcontroller (in this case a teensy running with the Arduino C++ tool chain).

This is part of my Fingerphone instrument.

Audio Sine and Square Wave Signal Generator using a Wavetable

Not my first publication, but my first one with some challenging engineering. I did this in my late teens and it was published in a hobby electronics magazine, "Electronics Australia". https://adrianfreed.com/content/audio-oscillator-using-digital-ics

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.

Augmented Electric Guitar

Experimental surface sensing for fingerstyle players

e-textile Interactive Demonstration at Maker Faire 2007

My table at Maker Faire 2007 including my first e-textile work with peizoresistive fabric, and my duotouch pad and floor sensors.

In 2016 I made the video below of a tear-down of those e-textiles with Hannah Perner Wilson.

Our Maker Faire table also include some great interactive demos whipped together by Andy Schmeder.

Michael Zbyszynski dropped in and talked about his Ikea bowl speakers.

It was great that Dan Overholt was nearby demonstrating his e-field sensor array.

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