Because this project was for high school students it needed to be easy to assemble without advanced electronics skills. It also needed to be budget friendly.
Early in the design it was decided to use ping pong balls to diffuse the LEDs. This set the spacing of the LEDs to the 38 mm diameter of the ball. This created a new challenge as the convenient LED strips don’t match up to this desired spacing. Cutting up the LED strips into individual parts and rewiring them was not desired. David came up with a 3D printed matrix frame to mount the ping pong balls and would easily hold individual PCB mounted LEDs. The custom matrix is modular and allows for easy construction.
The individual ping pong ball holders mount into a larger matrix to hold them together and make it easier to wire up the LEDs.
The task of cutting and stripping wire for the 1800 solder joints was not one that David relished. He got creative and rigged up a jig using card stock to hold the wire and used a laser cuter to strategically strip insulation off the wire. The wire was then ready to be placed in the holder and be soldered up.
The display is controlled with a combination of a Raspberry Pi to generate the images and a Teensy 3.2 to send the data to the display.
The end result is a massive LED display that is fun to watch.
The electronics are replaced by this custom circuit board.
On Twitter, she explains “Unless the controller board is fried (like this one was) I recommend using an external converter over doing this, as they are nice vintage electronics and should be preserved if possible.” and “If it’s mint and functional I’d go for a ps/2 to USB adapter and leave the guts intact. This one came to me non-functional so I had to replace the membrane and control board.”
But replacing all the electronics did allow for small upgrades, such as replacing 3 LEDs.
A second PCB with 3 addressable LEDs allows them to be any color.
The lightsaber is controlled by a Teensy 4.0 and powered by LPG (compressed liquid propane gas) mixed with oxygen. The resulting plasma burns at 4000 degrees Fahrenheit and is able to cut through titanium. This powerful combination was made using a bespoke circuit design that you can find and inspect on the DigiKey site.
Hacksmith Industries has an active YouTube channel where you can find more of their ambitious builds.