March 09, 2014

Halloween 2013 - "Waiting" graphic

For the past few years, I've tried to wear a work-related costume to the office for Halloween, since my co-workers are really the only one who'll see whatever I make. May as well target it to them.

This year I decided to be a "Please Wait" spinner graphic, sometimes also called a "Whirlygig". I modeled it after the spinner we use on one of our internal websites.

The costume is based around an Arduino LilyPad, which I got a few years back when first learning Arduino. It came with a Li-Po battery, which was super small and light, yet strong enough to run the LEDs for quite some time.

Lilypad Arduino

I created the design for the shirt itself in photoshop, and ordered the shirt from Vistaprint, as they were really inexpensive (I think around $20). The result is a bit "duller" than I had hoped, but close enough.

Construction

I started with a thin cardboard square cut from a box of whole grain cereal (whole grain is important), cut to the same size as the red square on the front of the shirt. I drew four evenly spaced lines, each passing through the center to make a nice asterisk. This made a guide for 8 lights. The graphic I was modelling after had more, but I went with eight for simplicity.

I taped a small rectangle of a mirror-like plastic I had leftover from another project to each of the lines. This would help reflect light to the front of the costume, as I was hoping for a nice even rectangle of light from each LED, rather than just pinpoints of brightness. The mirrors also allowed me to see how awesome I looked while I did all this.

The lights on my model were in a much tighter circle than my costume, but I worried about being able to cut neat holes that close together, so I spread them out a bit.

I wired a postive and negative wire to each led using some high-gauge wrapping wire I had. Since the wire is so skinny, and the Lilypad LEDs have a hole on each side, I was able to avoid having to solder by just tightly looping the stripped end of the wire through the holes a few times. I figured I'd want to recover the components after Halloween, and solder would slow that down.

I laid the LEDs out over the mirrors, put one wire from each through a hole in the middle of the square, and taped them down with packing tape.

On the back, I twisted all the negative wires together, to cut down on the number of wires going to the Arduino.

I used the same wrapping technique on the Arduino side. I made the wires about a foot-and-a-half, as I wanted the Arduino away from the shirt design, to have easier access for charging, and to cut down on the bulk that would be on my chest.

I laid slightly thicker cardboard from one of the finer Tarrytown Italian eateries on top of the first square, with eight rectangular holes cut out. The cardboard was about the same thickness as the LEDs, which worked out great. I taped this cardboard to the base layer on just one edge, so I could still open it up like a book to access the electronics in case a loose wire needed some attention.

Over each hole, I taped rectangles cut from a milk jug, to cover and diffuse the LED light, and to add calcium. I used two layers.

I lined the inside of the shirt with packing tape, and cut holes in the shirt from the front with an X-acto knife. The tape helped cut down on fraying, and made for cleaner lines. I flipped the shirt back inside-out, and used spray adhesive on the shirt to join it with the cardboard square, being careful to line up the holes carefully with the LEDs. The spray adhesive made sure that the holes stayed flush up against the plastic. I hoped it would also cut down on any future fraying.

I used duct tape along the edges of the cardboard to help attach it to the shirt more firmly, as the spray adhesive likely wasn't enough.

I made a small cardboard envelope to hold the Arduino, and taped it to the inside of the shirt. This would hold the Arduino in place, but still let me pull it out to turn it on/off, and attach the charging cable.

I had the soldering iron out for a different project, so I ended up adding solder to the Arduino connections, and the spot where all the LED ground wires met up. I figured these spots would probably get jostled around the most, so solder would help. I left the LEDs un-soldered, since they were held in place pretty well already.

Performance

Overall, the shirt held up great. At first, the Arduino was constantly cutting out as I walked around, but then I realized the battery was dangling out and getting jostled. Once I tucked that in, I was good to go for the rest of the day. I periodically plugged myself back in for charging when back at my desk, so I never got to find out how long they ran. My longest stretch was an hour, with no sign of dropping out.

I had one LED occasionally drop out on me, presumably due to a loose connection, but a quick poke would bring it back to life.

The costume got a really good reception, and most people recognized the graphic I was modelling it after.

Overall, a big success!

Posted by Kevin at March 9, 2014 01:14 PM
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