Watch the video to get the full effect. (is there no way to embed in the forum?)
So in my typical fashion I discard any long term planning for a Halloween costume at the very last minute and take on insanely ambitious delusional projects in their place. It always involves a fair bit of scavenging and resourceful repurposing of things I’ve got laying around, this year it just so happened I had a bunch of WS2812 (Neopixels) LEDs and some styrofoam cups around the studio. I had seen people making cup lamps for a few years and then someone on my Instagram feed posted a picture of someone wearing one as a helmet. DING! DING! DING! insperation! Like almost everything I figured I could take it up a notch to near perfection with Der BlinkinLights. SPHERE:
So 76 x 8.5oz Styrofoam cups makes a pretty good head sized sphere with a gap for your neck shoulders. I tested solo style plastic cups at first but the melt pretty quickly at the sight of any hot glue so on to earth destroying styrofoam (hey it’s Halloween). Originally I tried 20oz cups which make a much larger and awesome sphere but I couldn’t find enough of them in stock locally so 8.5 oz it is.
I started by laying out a single row of cups defining the middle of the sphere, then just built it up layer by layer, the natural conical shape of the cups forming the curve of the sphere. The are glued to each other at two points on both the front and back edge. Sometimes the math works out and they make contact at 3 points on each edge, but not often. I certainly didn’t do a perfect job but hell this is a 'day before deploy' style project. A couple test fittings as it was coming into shape to make sure I had enough room for my stupid head. At the end I poked a little hole in the bottom of each cup so the LED could shine through with less brightness loss.
Eventual improvements might be a spandex cover to diffuse the light and obscure the cups a bit. Maybe a bit of foam inside to hold it steady and keep the hundreds of little solder joints from puncturing my face. LEDs:
Now I have just wrapped up a couple high profile jobs using WS2812 LEDs and so I have a ton lying around. 100 bare WS2812A, 1000 bare WS2812B, 60/m Strips, 144/m strips, Adafruit Flora sewable ones, the Adafruit breadboard ones, etc etc. SO MANY CHOICES!
I have tried in the past hand soldering the bare LEDs both directly to wire and soldering legs on them, this is a GIANT pain in the ass. These bare 5050 packaged LEDs are very fragile and designed for reflow use only. With a little practice it’s doable but the yield sucks and it take a lot of time. Maybe someday I’ll make a little jig for it, because I do see the need for these cute little guys with legs but this wasn’t the project for it. And of course this practice doesn’t deal with the needed capacitor which adds a whole other pain in the bottom.
Now I love the sewable Flora Neopixels, but I didn’t have enough on hand and frankly I find them a bit expensive in quantity. So something I’ve done a few times now is buy the WS2812 Strips (both 60/m and 144/m density) and cut individual LEDs off. They have tiny solder pads on the flexible pcb (the ones on the 144/m strip are TINY though) and include the needed capacitor. The value per LED is pretty great compared to rigid pcb based options. Just so happened I had a half used 144/m strip lying around so that’s what I used. 456 solder connections later, and 76 lengths of 2” 3 conductor ribbon cable latter I had the perfectly spaced strands for my sphere.
Used hot glue to stick all the little suckers into the interior of the cup. PAIN IN THE $$$. Many burns were burned. MICRO + HARDWARE:
Originally I was testing the code on a Teensy2 with the intent to throw it on a Teensy3 due to it’s ability to run off a 3.7 lipo without the need for external voltage regulation, but when I got to that phase it was very last minute before I had to be out the door and the interrupt ISR I was using to switch modes was acting super flaky so last minute I switched it all over to the FLORA. This is the second or third time I’ve made a decision like this and ended up with the FLORA. Almost always over power issues. FLORA has a great power system, LIPO-in JST plug, FET triggering on-off switch capable of switching the whole project, etc etc. Now I’ve internally made fun of FLORA in the past over it’s shape and lack of pins broken out, but it really has saved my butt a few times and isa very well deigned board.
The battery was a 12v LIPO I have used hundreds of in projects and love. It’s a little bigger than a pack of cards, has a beefy off on switch and barrel connector for charging. I rewired it for this project so all 3 of it’s internal cells are in parallel giving 4.2-3.7 volt output. I wish Adafruit would sell it, right now you can only get them from Amazon (‘spensive) or China in bulk.
Then I wired up an arcade button to the FLORA in order to switch modes, it was the beefiest button I had around. I also added a 4pin JST plug (also from Adafruit) to disconnect the battery/brain (Brainery?) from the helmet itself. I kept the Brainery in my inside jacket pocket and ran the button out my sleeve.CODE:
Code was all very straight forward, based on Adafruit's excellent Neopixel Strip library. I customized the library a bit and added some functions to make working a little easier, but as it comes from GIT it’s pretty damn good (ok it’s actually amazing). Did you read the part where I had this code running on three different boards within 15minutes of each other? ya that means it’s amazing.
blah blah blah CATS!