Rotating Disk Projector


After initially getting experience with the Linux command line through my experience working at Applied Research Laboratories over the Summer of 2014, I realized how much work could be done with a simple text-user-interface. Simultaneously, I wanted to have an ultra-portable PC, and realized that computing hardware was able to be minimized easily. The largest components of portable systems were the interfaces: the display and keyboard. Several portable keyboard options exist, but there’s no inexpensive portable display. I thought that by reducing the resolution of the display to the absolute minimum to produce readable text, a portable text-user-interface could be added to a small computer like a Raspberry Pi. As a proof of concept I laser-cut a disk with several small holes, which when rotated would create an 8x5 persistence of vision display. Using an ATTINY microcontroller and a hall effect sensor, a single LED was programmed to blink in series with the rotation of the disk, which would selectively turn a single pixel on or off. This proof of concept ultimately failed to do the low clock speed of the microcontroller and the instability of the brushed DC motor. A distinct varying pattern could be seen during the test runs, but a steady image was never formed. I intend to re-attempt this project with a brushless motor to enable more speed control, but I would like to have more electronics experience through my coursework before I pick it back up again.