Texas Instruments developed digital mirror devices, and the subsequent digital light processing (DLP) projector, starting in the late 1980s. The technology is a wondrous and fanciful application of micro-scale electronics and optics. Most of us that have tangled with these devices have had to learn their mode of operation from diagrams and our own imagination. But what if you just built one at a large enough scale that you could see how it worked? Well, [jbumstead] did just that!
A real Digital Micromirror Device (DMD) consists of hundreds of thousands of mirrors, which would be impractical to recreate. This build settles for a simpler 5×5 array made using half-inch square mirrors. It uses solenoids to move each individual mirror between a flat and angled position to create the display. The solenoids are all under the command of an Arduino Mega which controls the overall state of the display and shows various patterns.
It’s not perfect, with the mirrors not quite matching in angles at all times, but it demonstrates the concept perfectly well. When you see it in action with light bouncing off it, you can easily understand how this could be used to make a display of many thousands of pixels in a projector arrangement. We’ve featured some other DLP hacks before, too, so dive in if you’re interested.
Continue reading “Giant Demonstrator Explains How DLP Projectors Work”
The neon dot matrix displays in pinball machines of this era are finicky devices with a lot of stuff that can go wrong. On powering the display up, [Quinn] noticed a few columns on the left side of the display weren’t working. These machines have great diagnostic menus, so running a test that displays a single column at a time revealed two broken columns. However, when a solid fill test was run, all the columns work, save for a few dots in the upper left corner. This is an odd problem to troubleshoot, but after more tests [Quinn] realized dots in column five and six only work iff both adjacent dots in the same row are lit.
