Low-Tech Touchpad


In this project, Peter and I had to combine high and low tech materials.  The inspiration for this project came from the High-Low Tech lab at MIT as well as Squishy Circuits among many others which you can find at the course webpage.

We constructed a low-tech touchpad that you could use to control a mouse, or anything else that could use one or two dimensions of input. Here’s a video showing it in action.

How does it work?

The touchpad has three layers. The top and bottom layer are resistive fabrics, which means they conduct electricity but not quite as easily as copper wire does – so more fabric between two leads increases the resistance between those leads. The middle layer is a conductive fabric, which means it conducts electricity just like a wire – with very little resistance between any two points on the sheet.  Here’s Peter’s concept sketch.

Concept Sketch of the Low-tech touchpadSo how does it produce an (X, Y) point reading?

Circuit diagram of one layer of the touchpad

Circuit diagram of one layer of the touchpad

Take a look at the image above.  It shows the top and middle layer of the touch pad.  The middle layer is connected to ground and remember since its very conductive connecting it to ground makes the whole sheet basically the same voltage.

The top layer is connected as if it were a resistor in a voltage divider. The sweet trick is that second resistor in this faux-divider is dependent on how much material is between the voltage source (top of the sheet) and ground (where you touch the top sheet to the middle sheet.

One technical detail is that the edge of the top sheet which has the power applied to it has conductive thread running through it so that the voltage is the same in the horizontal direction and only changes in the vertical direction.

Hopefully you see where this is going, the bottom layer is exactly the same as the top layer except rotated 90 degrees and bam, the reading from one layer gives you a vertical position and the other layer gives you a horizontal position.

Here’s a few more photos; some of early prototypes.  Thanks for reading!

Earliest Prototype - Graphite on paper with a copper tape layer.

Earliest Prototype – Graphite on paper with a copper tape layer.

Prototype - Conductive paint on normal fabric

Prototype – Conductive paint on normal fabric

Resistive fabric taped to cardboard with conductive fabric in between

Resistive fabric taped to cardboard with conductive fabric in between

Final prototype next to a graphite on paper switch

Final prototype next to a graphite on paper switch

Peter demonstrates the low-tech touchpad

Peter demonstrates the low-tech touchpad


Fuzzy Adventure: An Arduino Music Project

This semester I’m taking Jon Froehlich‘s Tangible Interactive Computing class.  For out first assignment we were tasked with creating an input device; no restrictions, it could be as narrow or as broad as we wanted.

My partner, Alina Goldman, and I decided to make a physical device for controlling electronic music called Fuzzy Adventure.  Our motivation was to bridge the divide between what you see and what you hear when experiencing an electronic music performance. What are the artists doing? How are their slider shifting, button pushing and knob tweaking affecting the sound? Sometimes its really hard to tell.

Enter Fuzzy Adventure, where physical artifacts or constants physical actuation are the only ways to manipulate sounds.

 Aside: Obviously, this is a tiny prototype and it's not *that* useful 
        for making music, but its the ideas we wanted to capture, 
        not a full-blown piece of DJ equipment.
Fuzzy Adventure Music Controller

Top view of the Fuzzy Controller Box

The Fuzzy Controller can manipulate the volume of three looping music tracks – drums, bass, and synth – as well as the level of a Bit Crush effect on each track. The music is started by placing the Power Cube onto its position.

Close up of the location for the Power Cube.  Power Cube is missing

No music plays without the Power Cube

Close up of the Power Cube completing the circuit to turn on the music

Placing the Power Cube on the leads turns on Fuzzy Adventure







The volume of the drum and bass tracks are controlled by adding weight to the cups on the left. This is an example of a physical manifestation of the intent to raise the volume of a track. The persistent change in volume is consistent with a persistent weight in the cups.

The drum track’s Bit Crush is controlled by crushing the Power Flower on the right of the box. Pipe cleaners give the flower structure such that a crushed flower remains crushed until its deliberately expanded. Again, in this way the artist’s desire for a constant sound change is accompanied by a physical, and visible, artifact.

The bass track’s Bit Crush is instead controlled by the proximity sensor in the blue circle. Only when something is within a few centimeters of the sensor will the effect be applied. This is an example of a transient effect that is only realized through a constant physical actuation by the artist. If they move away from the sensor, the change is revert and thus apparent to the audience.

Lastly, the Synth volume and Bit Crush are controlled by two touch membranes in the center of the box. These have the same property as the proximity sensor in that the artist much physical touch the sensors in order to include the synth sounds in their performance.

So enough talk, here’s a short demo video.  Enjoy!



Fuzzy Adventure is powered by an Arduino which reads input from 6 sensors and a switch and writes to a Serial port.  The inside looks like this:

Fuzzy Adventure Circuitry

Not the cleanest of wiring, but hey, its a prototype.

Then a Processing sketch reads from the Serial port and manipulates the music based on the sensor values. Here’s the source Code on GitHub.