Currently I am working on a project where I have been sewing a circuit into a hat (which is the style of the old aviator hats). It has a felt outer shell and an inner lining made of linen. My intention for this project was to have the circuitry covered by the felt layer and all of the circuits sewn into the linen layer, with the LEDs popping out into the felt layer. Felt is a great fabric to work with because you can make holes in it and it will not fray.
Ian Hanschen drafted out this circuit using the software Circuit Wizard, which is a great way to run a simulation of a circuit if you don't feel like setting it up on a bread board. The circuit is a LED flasher with 8 LEDs. 4 flash on one side of the hat and the other 4 flash on the other side.
I sewed the traces using my sewing machine (with conductive thread in the bobbin) and attached all of the components by hand. What I have discovered is that conductive thread actually contains a great deal of resistance. I am measuring about 80 ohms for every 10 inches of thread.
Here is the originally sewn hat with all of the traces sewn on with a machine.
This will definitley impact how many ohms my resistors may have to be and how long I run my "traces".
When the thread is sewn by hand, I double the thread, creating a bundle, which decreases my resistance by half. I began replacing the traces I had sewn hand stitched lines.
The other issue I seam to be running into is when the hat lays flat the circuit seems to work, but when it flexes, I loose connections. I believe this is because the connections between the thread and the components are not strong enough. Each time the hat is flexed the joint between the components and thread is articulating too much, causing it to short. I've also noticed that when I bring 2 traces together, I am also not making good contacts. Below is an example.
Back in the lab...shooting trouble, until I remedy these issues.
Later...
No comments:
Post a Comment