During the Spring 2014 semester I, along with my engineering class group, created an LED display using only seven spinning LEDs. A Matlab graphical user interface (GUI) was also created to let users input and wirelessly transmit custom messages.
Taking advantage of the human eye’s tendency to retain information for a fraction of a second, a large screen can be created using only a few sources of light. LEDs, while moving across the viewer's field of vision, can blink so fast many individual blinks blend together to make a static image.
A box fan was retrofitted to rotate the LEDs in a circular path. After cutting off the old blades, a wooden board was attached to the motor. All of the circuitry and materials were attached to the board. The biggest challenge was counterweighting the board to get the display up to full speed.
To send he message from the computer to the machine, words and phrases are converted into a matrix of ones and zeroes, and then into a flat array. The array is then sent over Bluetooth to an arduino (a small microcontroller) attached to the LEDs. The arduino interprets the array and determines when to turn the LEDs on and off.
After many weeks of building and coding, as well as burning through the first box fan, the project was a success. The display rotated fast enough and blinked rapidly enough to create the illusion of a display.
Click here to read more about our project in the final report.