[shakirfm] sent us this LED persistence of vision (POV) laser projector that can display dot matrix style text. The laser projector contains a rotating mirror assembly and 5 lasers. We’ve covered other POV projectors,but this one is a bit different. The mirror assembly rotates using two cooling fans. Controlling on/off times of the lasers along with the mirror speed, it is able to project 8×5 dot matrix ASCII text onto a surface.
Continue reading “Laser POV Projector”
Projectors have long been a favorite toy of hardware hackers. From reactive displays to cheap home theater, there are plenty of reasons to play with photons. Seeing some cheap projector repair put us in the mood to cover some of our favorite projector projects – check em out after the break.
[Johnny Lee]’s back again with his Wiimote interactive whiteboard. Commercial versions of these things are expensive and heavy. His technique doesn’t even need a projector, just a computer, a Wiimote and a simple IR emitting pen. The pen is just a stylus with an infrared LED in the tip. Hit the video after the break, and you can grab the software from his site here.
The Trinket Contest has drawn to a close, but we’re still going to show off the entries that were received by the deadline. The contest asked you slap the Hackaday logo onto something for a chance at winning one of 20 Trinket dev boards donated by Adafruit. See a dozen of them shown off after the break.
There’s a pleasing retro analogue experience to shooting Super 8 film, giving as it does the feel of a 1970s home movie to your work. But once you’ve had the film developed, there’s a need for a projector to enjoy the result. Far better to digitize it for a more modern viewing and editing experience. [Elbert] has made a digitizer for 8mm film which takes the best approach, snapping each frame individually to be joined together in a video file as a whole.
The frame of the device is 3D printed, but some parts of a film transport must be higher quality than a printed part can deliver. These, in particular the sprockets, are salvaged from a film viewer, and the movement is powered by a set of stepper motors. The steppers are controlled by an ESP32, and the optics are provided by a USB microscope. All this is hooked up to a PC which grabs each image, and finally stitches them all together using ffmpeg.
As anyone who has dabbled in 8mm film will tell you, there is a lot in the quality of a film digitizer, and it’s often worth paying for a professional job from someone aimed at the film-making world rather than you local photographic print booth. It would be interesting to take a look at this device, and see whether its quality is worth pursuing. After all, some of us have been known to dabble in 8mm film.
It shouldn’t be a surprise that the idea of a planetarium originated with an electrical engineer, [Oskar von Miller] from the Deutsches Museum in Munich. According to [Allison Marsh] in IEEE Spectrum, he thought about the invention in 1912 as a way to demonstrate astronomical principles to the general public. While it seems obvious today that you can project the night sky onto a dome, it was a novel thought in 1912. So novel that the Carl Zeiss company first told [von Miller] to take a hike. But they eventually reconsidered and built the first planetarium, the Model I.
The engineer for Zeiss was a mechanical engineer by the name of [Walther Bauersfeld]. He was familiar with mechanical devices — orreries — that tracked the motion of the stars and planets. The goal was to translate those movements into a moving projection of light.
Continue reading “The History Of The World’s First Planetarium”
We are always fascinated when someone can take something and extend it in a clever way without changing the original thing. In the computer world, that’s old hat. New computers improve, but can usually run old software. In the real world, the addition of stereo to phonograph records and color to photography come to mind.
But there are few stories as strange or wide-ranging as the path to provide color TV. And it had to be done in a way that a color set could still get a black and white picture and black and white sets could still watch a color signal without color. You’d think there would be a “big bang” moment where color TV burst on the scene — no pun involving color burst intended. But there wasn’t. Instead, there was a long, twisted path with many competing interests and ideas to go from a world in black and white to one tinted with color phosphor.
It is hard to imagine, but John Logie Baird transmitted color images as early as 1928 using a mechanical scanner. Bell Labs had a demonstration system, also mechanical, in 1929. Baird broadcast using his system in 1938. Even earlier, around 1900, there were attempts to create mechanical color image systems. Those systems were fickle or impractical, though.
Electronic scanning was the answer, but World War II froze most consumer electronics development. Baird showed an electronic color system in late 1944. However, it would be 1953 before NTSC (the National Television System Committee) adopted the standard color TV signal for the United States. It would be almost 20 years later before SECAM and PAL were standardized in other parts of the world.
Of course, these are all analog standards. The world’s gone digital now, but for nearly 50 years, analog color TV was the way people consumed TV in their homes. By 1941, NTSC produced a standard in the United States, but not for color TV. TV adoption didn’t really take off until after the war. But by 1950, the US had some 6 million TV sets.
This was both a plus — a large market — and a negative. No one wanted to obsolete those 6 million sets. Well, at least, the government regulators and consumers didn’t. But most color systems would be incompatible with those existing black and white sets. Continue reading “The Long Strange Trip To US Color TV”
