Intro: Halo Cortana Neopixel LED Scarf
From the game world of Halo comes the computer generated character of Cortana, but now you can have those circuits activated around you with this scarf. If you just need a MA5B, look here.
This project is based on the Adafruit Cyber Falls light up headwear which uses the Adafruit Trinket microcontroller and Adafruit Neopixel LED strands.
CAUTION: Lots of electronics stuff and sewing stuff done here. Tools and equipment used can be hazardous. Learn to safely solder and sew.
Step 1: Sew What?
You will need fabric for your scarf.
I got some baby blue fleece, hmmm, leftover scraps for some kind of Adabot project...
A darker blue fabric for the trim details.
A stiffer or more sturdy kind of fabric for an underlayment, substrate or base to mount the electronics to. I found this felty kind of wool remnant material at the fabric store.
A sturdy gauze or mesh material to form the cage for the Neopixel strips. I used this mesh ribbon xmas decoration stuff which was not really woven so it tore easily. Don't use that.
Batting in sheet form to diffuse the Neopixels
You could do this by hand sewing but recommended is a sewing machine. Use of a serger is nice too.
Nylon tie-wraps to secure the electronics to your fabric substrate.
Step 2: Derivation Is the Sincerest From of Flattery...
The electronics for this ible is based on the Cyber Falls Wig tutorial found on the Adafruit Learning System.
They do a pretty good job of showing you how to put together the electronic effects for this Cortana scarf so look there.
The Cyber Falls Wig is essentially an Adafruit Trinket (Attiny85 based microcontroller board) programmed to light up several Adafruit Neopixel LED strips. The Trinket can be programmed with the Arduino IDE.
I used the same code but switching out the variables Green for Blue and Blue for Green changes the original green color scheme to the blue color scheme. There is also a resulting red color accent flare. I am not that familiar enough to manipulate the color gamut of the Neopixel strips yet. Ok, I was too lazy to reference an RGB color value table and figure things out.
I had originally wanted to get a few Neopixel strips to make some of the other cool projects like the Firewalker Shoes but Neopixel strips make programming sequences of LED lights so easy and was suited for the Cortana scarf.
The Neopixel strips come in 1 meter lengths which you can to cut apart to fit your project needs. Since I ordered the higher density 60 LEDs per meter strips, I started to halve each one. They seem to be factory soldered and joined in 30 LED segments. Read up on the Adafruit tutorials so you can work with these strips and heed the cautions.
I did roast off the ends of two strips that I made. Too much soldering and heat will melt off the plastic strip or flexing the soldered wires will peel off the fragile solder pads. Instead of hot glue I used some kapton tape to seal the ends and then overwrapped with electrical tape for additional strain relief. Use stranded wire, even better, the silicone casing wire which is very flexible.
When prototyping, it is handy to make things modular or plug in. I built a little breakout board to hook up to the Trinket. I knew that I had to power up my 5 Neopixel strips (max 5 control pins on the Trinket) so having a plug in board with common power rails like a breadboard would make things neater (maybe electronics OCD somewhat, actually good for troubleshooting). I have a whole big bunch of headers and pins so I made the breakout board with a small chunk of perfboard. After I read all the tutorials again, I should have also put a capacitor on the power lines and some resistors on the signal lines to prevent possible damage to the expensive Neopixel strips. Do that.
Step 3: Jeffries Tubes...
Cut your substrate fabric to 4 inch wide strips.
You can piece together a length to about 104 inches, go ahead, convert that to centimeters...
The scarf is extra long because I wanted it to do a full wrap around the neck with the two tails draping on each side.
Place your Neopixel strips in position and cut a corresponding length of mesh fabric or ribbon to cover it.
Sew that to the substrate by binding both sides to the edges.
You can then sew dividing lines to create tunnel pockets for the Neopixel strips.
If you watch the video, you will notice that the "icicle drip effect" goes in two directions. Sure, you could code it, but you are messing with some compact code and mods might not fit in the limited memory of the Trinket. I took the other alternative, do a hardware mod and just extend the wires to two of the strips and mount it upside down in relation to the others.
Pick a spot where you will mount the Trinket, the breakout board, and the battery pack, I should have wired in an on/off switch somewhere.
Snake in the Neopixel strips in position.
Extend all of your wires as necessary to connect it all together.
Test. Test. Test.
Step 4: Kinda Like TRON...
Double a strip of fabric about 6 inches wide x 106 inches long for the scarf. Maybe a bit wider for seam allowance. You can piece together if needed for a top layer and a bottom layer.
Cut out some trim pieces for the details.
Pin in position and applique on with a zigzag stitch like a quilt or patch.
Finish the ends with a folded over piece of trim or you can hem the bottoms of the scarf later.
Fold in half lengthwise with the good side inside.
Seam along the entire edge to close off the tube for your scarf.
And what I learned, somewhere along the middle, leave an access opening so you can change the batteries or turn the scarf on and off without having to snake it through the entire scarf tube.
Turn inside out so that you have a nice finished edge on the outside.
Step 5: Stuff It...
Organize your wiring harness by using tie-wraps to secure loose wires to the substrate.
Place one or two layers of batting over your mesh Neopixel assembly to diffuse the discrete LEDs. You could probably make another mask for finer detail on the lights by using a circuit template design that was toner printed on a transparency gel. It would be great to just textile print the design on the fabric outer layer.
Snake it through the scarf tube covering. I fished the end of my tape measure through the scarf and taped it to the end of the substrate to help pull it through. If you were smart enough to have an access opening large enough in the middle of the scarf, feed it in from there to the sides.
Adjust all the jiggly things inside and flatten out the scarf.
And there you have it, an Halo Cortana Neopixel LED light up effects scarf.
Lava lamp scarf, anybody?