Wearable Arc Reactor

I know arc reactors have been done to death, but I couldn't find any models that met my personal preferences. The attributes that I value in this model are:

• it's designed to be worn underneath a shirt
• low-profile and not bulky
• bright enough to be seen through clothing
• adequately diffused light
• the patterns are reasonably close to the ones in the movies
• the cover plate can be swapped out for different patterns

I made a few design decisions to achieve a low, sleek profile. First, I used wide angle SMD LEDs to reduce model depth. Then I incorporated a sheet of 2.4mm white acrylic (cut into a circle) to help diffuse the light and achieve that classic blue-white glow. Finally, I opted to power the lights with a 9V battery that sits in my pocket instead of trying to fit batteries into the housing itself. It stays in position with some simple twine tied around my chest. Everything is press-fit together.

If you want to design a custom cover plate, the housing has an inner diameter of 76mm. The cover plate has a height of 4mm. The inner diameter of the cover plate is 73.7mm (you'll need to cut the acrylic sheet to fit inside that diameter).

Circuitry:

There are a number of ways to go about lighting the inside, but here I'll describe my own strategy.

My own circuit is based around the 9V power supply. The circuit consists of 7 “sets” of components wired in parallel. Each “set” is composed of two SMD LEDs and a single through-hole resistor wired in series. The SMD LEDs that I used are rated at 3.2V and 20mA (as stated by the spec sheet), so the correct resistor value can be calculated via Ohm's law:

V = I*R

9V - 3.2V - 3.2V = 20mA * R

R = 2.6V / .02A = 130Ω (or greater)

I stripped a couple wires and formed two loops in the housing: an inner loop (positive) and an outer loop (negative). Each set of serial components connect to the inner loop on one end and the outer loop on the other end. The circuitry is held in place with hot-glue (this part was actually a pain in the neck, so I'm considering designing a PCB to make this part easier in the future). The final touch is a rocker switch added by the battery.

Disclaimer: this model is intended to look cool when worn underneath clothing, not as a prop in a display or anything.