This t-shirt interfaces with a toy piano, allowing for people to play music on my back. Fabric Buttons replace the keys, poppers connect to the circuit so that it can be connected and disconnected from the t-shirt. This allows for all of the components on the t-shirt to remain wearable and washable.

This particular Instructable is made for the Electronic Textile workshop that will be held in Zurich/Switzerland on Saturday 7th December 2009 as part of the DIY Festival Zurich. If you are interested in this workshop, please contact the festival.

OUTCOME

Even though the outcome of this Instructable is a t-shirt, you can choose to design your own design that incorporates fabric buttons and fabric pressure sensors and fabric bend sensors.

Each step includes both specific and general instructions to help you create your own wearable interface.

I have to admit that I'm not very happy with the way this project turned out. But now I know what to do better the next time. The biggest problem i had was with the connection between the 3V power supply and the circuit. When I used conductive fabric traces it was not getting enough juice to run, although the multimeter showed no loss in voltage. So I had to make a straight wire connection between circuit and battery pouch. Also, the buttons on the back were not made very well and it is not actually very fun to play. Though I hope I got the idea across and that I'll be able to use this Instructable to accompany the workshop.

WORKSHOP PREPARATIONS

Step 1: Materials and Tools

Toy piano from http://www.shopatron.com/product/part_number=MEP/329.0
T-shirt or other clothing item
Extra jersey fabric
Regular thread
Conductive thread from http://www.sparkfun.com
Stretch conductive fabric from http://www.lessemf.com
Velostat by 3M from http://www.lessemf.com
Machine poppers/snaps from local fabric store
Flexible wire in different colours

TOOLS:

Pen and paper
Fabric scissors
Sewing machine
Soldering station
Wire clippers and strippers
Screwdrivers
File
Small saw or cutting tool
Cutting knife

Step 2: Hack the Piano

Open up
Take everything apart, strip down to the bare circuit
Take photos and notes, document the process

Before opening it up, make sure to play with the piano to see how it is supposed to work!

Step 3: Understand the Circuit

Exchange wires for more flexible ones
Experiment with connections and find out where power, ground, input and outputs are
Identify components
Use your notes to analyze the circuit and draw a circuit diagram

Results for Schylling toy piano:

Power source: 2 x 1.5V battery (see: Fabric Battery Pouch)
23 keys using 11 microcontroller connections (different combinations of the first 3 and the last 8)
One 470 K Ohm resistor (can be exchanged for a variable resistor to manipulate sound output)
No on/off power switch, but this can be created
Two connections that go to loudspeaker

Step 4: Prapare Your Circuit

Minimize your circuit, take all extra material away, see how small you can get it and then decide on interfacing method between t-shirt and circuit:

poppers
hooks and loops
conductive Velcro
fixed connection
metal magnets
...

Solder wires to connection points on circuit and create strain relief. Attach connectors to end of wires.

How the circuit works after being hacked >>

Step 5: Design Your Wearable Circuit

Draw your t-shirt or other clothing item onto a piece of paper and design your interface. Before you think about how you are going to solve any problems, just draw your design. Be creative, inspire your design from crazy ideas, funny interaction scenarios and wishful thinking.

My example: I'm addicted to back-rubs, so my design places the buttons of the piano on my back for people to play with and rub my back at the same time.

Consider:

How many buttons, variable resistors and switches does the circuit have?
How many of these elements do I want to use? (I don't kneed to use all of them)
Layout - Where do you want what to be?
Colours, shapes, sizes...
...

Now we need to integrate a fabric circuit into your design. For this you need to understand the following soft circuit methods:

Sewing with conductive thread
Fusing conductive traces to fabric with fusible interfacing
Stretchy conductive trace: using stretch conductive fabric and fusible interfacing
Isolating stretch conductive traces with stretchy fabric glue
Soldering loops to connect between poppers or to sew with conductive thread
Forming Shapelock to embed components and make them sewable
...