So I recently graduated from Arizona State University with a Bachelor’s degree in Mechanical engineering! whoohoo.

So the day before my graduation ceremony, I decided that I wanted to do something with my mortarboard. I have been meaning to build a simple LED matrix for some time now, and I decided it would be the perfect opportunity to make one! So at 4:30 pm, the day before graduation, I started the sketching out my design for the LED mortarboard. In order to display aplha-numeric messages, I determined that at minimum a 5×4 LED matrix would be necessary to display most of the characters of the alphabet and all the numbers (except for M and W). I based the wiring design and code around the Arduino direct-drive LED matrix information from this link.

In order to construct the LED matrix on the mortar board I first measured out the mortarboard, and laid out a pencil grid of lines in order to evenly space the LEDs. The mortar board was made of cardboard, so it was relatively easy to then poke two holes for each LED at each of the spots. I then inserted each LED through the holes and made sure to align the cathode and anodes in corresponding directions to make soldering the matrix easier. 

Once all the LEDs had been inserted, I then cut and stripped wire harnesses that lined up with each of the LEDs. In order to securely attach the LEDs to the wiring, I first hooked each of the LED leads as shown below 

I then crimped each of those hooked legs around the pre-tinned wiring harness, added some heat and boom, instant strong solder joint! 

I repeated this process for both the rows and columns, and routed the ends into the cap itself to semi-hide the birds nest of wiring.

To make it easy to plug into the Arduino I soldered some male headers on the wires. To power the whole thing I used 4x AA battery pack from sparkfun, and ran the power wires from my pocket up to the mortarboard.

fun messages scrolled by the mortarboard included, “ASU Class of 2012 is 1337″, and “Feels good brah”

here’s a poor quality video of the thing in action!

Total time of the project from “hmmmm I should make something” to finish ~ 8 hrs