Intro: Simple Zipper Potentiometer
One application of wearable technology is a zipper slider potentiometer. This has been explored previously in several projects:
The above are all excellent examples of zipper potentiometers -- but they are complicated. We decided on a simpler method for creating an analog zipper potentiometer in our project:
There, we used a zipper slider to control the volume of a music-playing pillow.
This instructable was made as part of the CS graduate course "Tangible Interactive Computing" at the University of Maryland, College Park taught by Professor Jon Froehlich. The course focused on exploring the materiality of interactive computing and, in the words of MIT Professor Hiroshii Ishii, sought to "seamlessly couple the dual worlds of bits and atoms." Please see http://cmsc838f-s14.wikispaces.com/ for more details.
Step 1: Zipper Slider Circuit
The underlying circuit is simple.
On either side of a zipper there is a conductive thread rail.
The power source runs to one of the thread rails.
We read analog values from the second thread rail.
The second thread rail runs down to a resistor and then the ground.
The metal zipper head bridges the two conductive thread rails increasing and decreasing the resistance of the system.
Step 2: Materials
For our simple zipper potentiometer there are relatively few materials.
- one zipper: metal head required; plastic teeth preferred
- some conductive thread: the more resistive, the better
- one resistor - we use a heavy duty 100 ohm
- lengths of wire
- one needle
- a pair of sharp scissors
- a multimeter
Step 3: Sew Things
In order to create your zipper potentiometer you will need to know a basic straight stitch.
You will begin by straight stitching two conductive thread rails on either side of the zipper. You want these rails to be close to the teeth of the zipper so that the head of the zipper will run over them. At the bottom of either rail sew two larger loops as leads to connect your wires. You may have to poke pretty hard, as the thread is stiff and you are trying to get the thread close to the teeth.
Step 4: Solder the Resistor
You will need a resistor in your zipper potentiometer. We choose to solder a resistor to some wires to simplify their addition to the system. We choose a 100 Ohm resistor.
Step 5: Put It All Together
Set up your circuit. We use an Arduino for power and ground. Attach the power to the rail with only one loop. Attach the ground and output to the rail with two loops (one loop each).
You can see our setup in the above video.