This is my first Instructable! I'm a huge fan of Ms. Frizzle from the Magic School Bus series, an astronomy enthusiast, and a woman fascinated with e-textiles. I thought I should combine the three, creating a constellation dress to wear to Dragon Con 2013. I started working on ideas for the skirt back in November, when I planned to work with existing light strands. After deciding that I couldn't customize distances between the stars and knowing some -very- basic circuitry, I started researching e-textiles. The conductive thread I tested oxidized after about three months, and I wanted this skirt to last for years, so I decided to use ribbon cable, which gave me both cost-effectiveness and flexibility.
Step 1: Arranging the Constellations
Once I'd decided to do several constellations, it was time to figure out which ones I wanted to do. My favorite constellations needed to be included, and I went in search of the perfect sky. I felt a bit like Neil deGrasse Tyson and his complaint about the night sky in the movie, Titanic ("We know the day, the date, the time, the weather conditions, the longitude, the latitude...we know all of this about the sinking spot of the Titanic. There is only one sky she should have been looking at - and it was the wrong sky!" - Dr. Tyson, in an interview with Stephen Colbert at The Kimberley Academy in Montfort, NJ, January 2010). Dr. Tyson is my hero, and I wanted the skirt to be accurate. My type-A, OCD, science nerd kicked in - I determined to do the sky at the moment of my birth, from the place of my birth. It wasn't going to be the complete sky, but this skirt was going to have 151 LEDs. I sat down to plan, getting out my favorite astronomy app, GoSkyWatch, and programmed it to see what was overhead that day. I picked from among the constellations, and created a sketch. The skirt I'd sewn was a six-gore circle skirt, so I used the seams as guidelines. I spread the constellations out a bit so that the images wouldn't overlap. I made one design change after this skirt - I moved Ursa Minor to the hem of the skirt and away from where it would be sat on. No one wants Polaris adjacent to...Uranus.
Step 2: Hand Painting the Skirt
Using some fabric paint and a fabric paint brush, I spread my skirt out on the floor, put paper underneath it so the paint wouldn't go through to my carpet, and began painstakingly free-handing the constellation pictures. Please forgive the color variation - I was painting on my screen porch and the sun set, so the first ones are during daylight and the last ones are under a floodlight.
Step 3: Sewing the Stars
I ordered flat-top super bright 5mm LEDs online for about $0.07 each, getting twice as many as I would use on the skirt - that way, I could replace poorly constructed ones, dim ones, or ones I broke throughout this process. Using jewelers' pliers, I made the positive leads into flat "o" shapes and the negative leads into squares. Doing so let me treat the LEDs as beads or sequins so that I could sew them into the skirt easily. It also meant that I was saving money since I'd pay at least three times that price for LED sequins. I sketched the way I wanted the wiring to go and stitched in the LEDs so that it would be relatively easy to do the soldering later. I planned on 11-13 parallel-wired LEDs for each circuit. The 13 circuits would then be run in parallel with each other. The wiring diagram for Ursa Minor shows the shapes of the leads. I've added circles and squares to that image, as well, since not all of the leads are clear in the picture.
Step 4: Preparing the Wiring
I bought a 15-ft. rainbow ribbon cable online and separated it into its ten individual colors. If you've never done this before, the hardest part is keeping them neat and tidy once separated. Put your thumbnail in the groove between two wire colors and slowly pull the wire on the end away from the rest of the ribbon cable. I chose to use warm colors for positive and cool colors for negative, using the same color pairs to create circuits, like red and gray or orange and blue, which would make wiring that much easier (and my OCD much happier).
Step 5: Testing the Circuits
With the extra LEDs I hadn't put into the skirt, I began testing my power needs on a breadboard. I'd chosen 9V rechargeable low self-discharge batteries, and found a set of 10 and a charger online. These are great, and typically used for RC applications, which made them ideal for my situation - I, too, had a high-drain situation, and was counting on a battery setup only lasting an hour or so. I set up my parallel circuit, running 96 LEDs on my breadboard with two 9V batteries. I chose not to use a resistor, wanting to see what the LEDs and batteries could take. To test the battery life and light output, I ran my tests in a sealed shoebox with a Vernier light sensor gathering and graphing data for me. The graph showed that I would get about an hour and 15 minutes of LEDs at the brightness level I wanted. I ran the test four times, with a different pair of batteries each time; I got the same result in each test. Time to solder!
Step 6: Soldering the LEDs
Using wire strippers, I stripped the coating mid-wire, and set out removing 2-3" from the end before laying the wire along my circuit and matching it with the gap between LEDs. It was the most time-consuming game of "connect-the-dots" I've ever played! Once I'd made a gap, I very carefully slid the coating down towards the bare end of the wire, leaving a 2-3mm gap for each connection. When my wire was ready, I began tinning the wire and the leads with the soldering iron. I'd learned how to solder specifically for this project, and I'm proud to say that I did a decent job. I encountered a few cold solder points upon wearing the skirt, so, now that I'm not under a con deadline, I'd like to go back over the whole skirt again. I'm also planning to use liquid tape to protect the exposed wire. Once I finished the primary circuit for Orion, I tested it with my 9V. I was really thrilled with the result, and set to the rest of my circuits, testing each as they were soldered. I installed a primary positive wire and negative wire at the waist, using the same "connect-the-dots" method as before, and hooked up my batteries.
Step 7: All Done!
I wore a petticoat under the skirt to keep light from coming through where it wasn't supposed to. It also gave me a barrier between myself and the wires. The finished skirt was incredible, and the batteries didn't get too warm, but I'm still tinkering with the idea of a resistor, just to keep them cool. I wore it on Sunday of Dragon Con 2013 and had a ton of fun teaching people celestial navigation and the stories from mythology. I also use it at the science museum where I run the camps program, and I've worn it to a local observatory. Now...to send these pictures to Neil deGrasse Tyson...