So I got the itch to create. With Halloween coming up, and the Iron Man 2 DVD release last week, I felt compelled to finally get off my hindquarters and get busy on an arc reactor. Seems like dressing as "Tony Stark" for Halloween would be a grand idea. A quick search of other people's ideas on the net produced many good examples, but somehow copying someone else's work didn't seem right.
So here are the ingredients of TAE's DIY Arc Reactor:
1. 9000k white 20mA LED quantity 10
2. 100 ohm resistor quantity 10
3. Custom parts made on an Objet Eden 250 3D printer (handy to have one of these!)
The first step was to drill ten LED mounting holes in the back side of the clear poly ring. I then made custom black parts on the Objet that acted as the wrap points for the magnet wire, while also concealing the LEDs from view. I then glued the LEDs in the back side. Each black mounting point then got a treatment of about 25' of magnet wire winding. The reason I used magnet wire and not bare copper was so that I could just run the LED anode and cathode bare right through them without worrying.
Once the magnet wire wrappings were done (6 hours later, blech!), I started soldering the LEDs together. Basically, all the LEDs are in parallel with a 100 ohm resistor behind each. That way, they all can run on 5 volts without negative damage. For a quick tutorial on LEDs in series or parallel go here. Put in source voltage 5 volts, forward voltage 3.2 volts, forward current 20 mA, and quantity 10. You'll see what I mean.
Now that the LEDs were all wired together and blazing hot bright, it was time to make the housing. I happen to be a whiz at Solidworks thanks to my job, and I have an Eden 250 about fifteen feet away from me as I type this, so it was no big deal to draw up the core and the outer housing, complete with mounts on the back side for a chest strap. Once the parts were printed, I soaked them in 2% NaOH for about 30 minutes, let them dry overnight, and then painted about 3 coats of Krylon brass spray paint on them to get the whole thing a kinda "Tony Stark made one in a cave with a box of scraps!" kind of feel. Also, that was the metallic paint I have on hand due to my steampunk obsession.
Once done, a little glue and a little assembly and voila. It was so easy that I really wished I had done it sooner!