There is no point to it but fun.
Update: Using some wire wrapped around the central popper to make contact with the resistive ring (circular potentiometer). Unfortunately (though cool too) the Eexonyx fabric is pressure sensitive, thus its resistance varies also on the pressure applied, not only on the position of contact.
Plus, the contact between the wire and Eeonyx is not stable enough. But this is a design issue that can be solved:-)
Video of update that eliminates the conductive finger-cap
Video of Time Sensing Bracelet in action
Video of first prototype
Step 1: Materials and Tools
- Eeonyx piezo-resistive SL-PA coated fabric RL-4-139-4 from http://www.eeonyx.com
- Conductive thread from http://members.shaw.ca/ubik/thread/use.html
- Neoprene from www.sedochemicals.com
- Stretch conductive fabric from http://www.lessemf.com
- Fusible interfacing from local fabric store or
- Male and female headers from Sparkfun http://www.sparkfun.com/
- Ribbon cable with min. 8 wires
- Solderable Perfboard with copper line pattern from All Electronics http://www.allelectronics.com/
- Arduino USB board from Sparkfun http://www.sparkfun.com/
- Regular thread
- Fabric scissors
- Sewing needle
- Soldering station (iron, helping hands, solder)
- Knife for cutting perfboard
- File for filing edges of perfboard
- Wire cutters and strippers
Step 2: Trace and Cut Stencils
Print out the stencil (see illustration) and trace it to a piece of neoprene. Trace the circle onto a piece of stretch conductive fabric that has fusible interfacing adhered to one side. Trace the disconnected ring and the small rectangle to a piece of Eeonyx fabric that has fusible interfacing adhered to one side.
Cut out all the pieces.
Step 3: Fusing
Lay the circle, ring and rectangle into place and fuse with an iron.
!Careful: the Eeonyx fabric will stick to your iron, be sure to put a piece of wax paper in between.
Step 4: Soldering
Cut a piece of perfboard 18 x 5 holes big. With the conductive strips running the shorter length. File the edges, but you do not have to round the corners, it is only for decoration.
Bend the legs of three male headers if you don't have any ready bent ones. Solder them to one of the corners of the perfboard.
Cut a piece of ribbon cable with five wires. About 1m long. Strip the ends of the 1, 3, 5th wire and solder to a row of three female headers. These will plug in to the three male headers on the bracelet.
Solder the other ends to the 1, 2 and 6th headers in a strip of six male headers, this will plug in to the 5V, GND and first analog input of your Arduino board.
Step 5: Sewing
- The circle will be your +5V
- The Ring will be your variable resistance
- The rectangle will be your pull-up resistor
The three conductive stitches come very close together and we want to make sure that they do not touch each other inside the neoprene, where we cannot see them. So you have to remember where you have stitched.
Sew from the circle of conductive fabric to the furthest left perfboard hole connected to a male header, bypassing the pull-up resistor.
Sew from the end of the pull-up resistor closest to the perfboard to the middle hole connected to one of the three male headers.
Sew from one of the ends of the ring to the other end of the pull-up resistor to the last hole of the three on the perfboard.
I attached a metal popper to the center of my conductive circle, because I wanted to be able to connected a piece of rotate-able metal to it, that I can turn and it will stay in one place making a constant connection there between the conductive circle and resistive ring.
One last thing we have to cut and sew is a little conductive finger-cap from stretch conductive fabric (no fusible interfacing). Trace your fingertip and cut it out twice, then sew together with conductive or non-conductive thread. Turn inside-out. Finished.
Step 6: Plug and Play
For Arduino microcontroller code and Processing visualization code please look here >> http://www.kobakant.at/DIY/?cat=347
Plug the headers into the right places and wear the bracelet. If all goes well you should be reading the inputs from the bracelet.
Now it is up to you to decide what time it is by placing your conductive fingertip wherever you want what time it to be.
Press the space bar to enter the visualization mode and press g to return to the graph mode. You can set the thresholds in the processing code.
Let me know if there are any complications. And enjoy!