What’s Inside A Super-Cheap Projector? Not A Lot!

December 18, 2022 by Donald Papp 39 Comments

[Raymond Ma] has a penchant for browsing Aliexpress and purchasing curious pieces of hardware that are as high on promises as they are low on cost. This is a process he aptly sums up with his opening line of “I should have known better, but…” Luckily, these devices all get torn down and analyzed so we can each enjoy and share a little slice of disappointment.

One such item is the $30 USD YT200 mini projector, which at 320×180 is almost as low on pixels as it is on cost. Still, [Raymond] looks inside to find out if there is perhaps more hacking potential than there is image resolution.

The YT200 lacks any kind of normal video input, and the anemic 15 lumen output is brazenly branded as a feature to protect children’s eyes from excessive brightness.

Light from the single LED is collimated with some Fresnel lenses. That light passes through an LCD panel, and from there the image bounces off a mirror and through a focusing lens housed in a spiral guide. Focal adjustments are made with a small lever, and the whole assembly provides just enough friction to prevent the lens from moving out of focus on its own.

The device actually does work fairly well for what it is: a way to play a range of different media types off a connected USB storage device. As long as one is in a dark room, anyway.

[Raymond] hopes to find some alternate use for the device. Might we suggest projecting into a frosted glass globe to create a sort of spherical display? A spooky eye animation on a USB stick might pair well with that.

Printed Film Camera Gets 10 Seconds Out Of A 35mm Roll

December 17, 2022 by Jenny List 17 Comments

When the British budget electronics brand Amstrad released their first budget VHS camcorder in the mid 1980s, they advertised it as making a filmmaker out of everyone. Now everyone truly is a filmmaker of sorts with their always-handy mobile phones, even though possessing a camera does not give you the talent of Steven Spielberg.

Such easy access to video hasn’t dimmed the allure of old-style film though, and there is a band of enthusiasts who seek out the older medium. [Joshua Bird] is one, and he’s produced a rather special 3D printed camera that can capture short videos on a standard roll of 35mm camera film. The downside is that, at the going rate, filming your masterpiece comes out to approximately $600 USD for each 10 minutes of footage. Better keep that dense exposition to a minimum.

The two most important mechanisms in a movie camera are the shutter and the film advance. The first is a disc that spins once a frame with an arc-shaped aperture over a section of it to let the light through, while the second is a hook that engages with the film once a frame after the shutter aperture has passed, to advance it to the next frame. Designing these to work in printed form is no easy task, and [Joshua] takes the reader through the various twists and turns in their development. Beyond that he takes a novel approach to a through-the-lens viewfinder, eschewing a split prism for an angled mirror on the shutter disk.

With each frame taking a fraction of the 35mm frame it’s clear from the video below that this doesn’t deliver the highest quality image. But that’s not the point of a device like this, above all it’s a working movie camera that he made himself. Since some of us have interests in that direction, dare we say we’re envious? Meanwhile, this isn’t the first 3D printed movie camera we’ve brought you.

Continue reading “Printed Film Camera Gets 10 Seconds Out Of A 35mm Roll” →

The Story Behind The TVGuardian Curse Catcher

December 14, 2022 by Chris Lott 23 Comments

The recent flurry of videos and posts about the TVGuardian foul language filter brought back some fond memories. I was the chief engineer on this project for most of its lifespan. You’ve watched the teardowns, you’ve seen the reverse engineering, now here’s the inside scoop.

Gumby is Born

TVG Model 101 Gumby (Technology Connections)

Back in 1999, my company took on a redesign project for the TVG product, a box that replaced curse words in closed-captioning with sanitized equivalents. Our first task was to take an existing design that had been produced in limited volumes and improve it to be more easily manufactured.

The original PCB used all thru-hole components and didn’t scale well to large quantity production. Replacing the parts with their surface mount equivalents resulted in Model 101, internally named Gumby for reasons long lost. If you have a sharp eye, you will have noticed something odd about two parts on the board as shown in [Ben Eater]’s video. The Microchip PIC and the Zilog OSD chip had two overlapping footprints, one for thru-hole and one for SMD. Even though we preferred SMD parts, sometimes there were supply issues. This was a technique we used on several designs in our company to hedge our bets. It also allowed us to use a socketed ICs for testing and development. Continue reading “The Story Behind The TVGuardian Curse Catcher” →

VHS-Decode Project Could Help Archival Efforts

December 13, 2022 by Lewin Day 47 Comments

Archiving data from old storage media can be a highly complex process. It can be as simple as putting a disk in an old drive and reading out the contents. These days, though, the state of the art is more complex, with advanced techniques helping to recover the most data possible. The VHS-Decode project is an effort to improve the archiving of old analog video tapes.

The project is a fork of the LaserDisc-focused ld-decode, started by [Chad Page] back in 2013, which readers may recall was used for the Domesday Duplicator — a device aimed to recover data from the BBC’s ancient Domesday LaserDiscs. VHS-Decode is designed to capture the raw RF signals straight out of a tape head, which are the most direct representation of the signals on the physical media. From there, these signals can be processed in various ways to best recover the original audio and video tracks. It’s much the same technique as is used by floppy disk recovery tools like the FluxEngine.

Despite the VHS name, the code currently works with several tape formats. VHS, S-VHS and U-Matic are supported in PAL and NTSC formats, while Betamax, Video8 and High8 tape capture remains a work in progress. Using the code requires a video tape player with test points or traces that make signals from the head accessible. Capturing those signals is achieved via a Domesday Duplicator hardware device, or alternatively a Conexant CX2388x analog-to-digital converter, often found in many old PCI TV tuner cards. Various techniques can then be used to turn the captured signals into watchable video files.

We love a good archival project, and VHS-Decode is clearly a useful tool when it comes to salvaging old video tapes. Continue reading “VHS-Decode Project Could Help Archival Efforts” →

CGA Competitors From The 1980s

December 12, 2022 by Chris Lott 25 Comments

[David Murray], aka The 8-Bit Guy, did an interesting video (embedded below the break) on the time line of PC graphics cards from CGA through to EGA. Not only does he explain the different offerings of the day, but also proceeds to demonstrate most of them.

It’s interesting to learn about some of the video modes that went basically unused in these cards. Even if board designers include high resolution modes and better color palettes, if software programmers don’t use them they are forgotten.

We were particularly impressed by a couple of examples he had that were full-sized, double-stacked ISA cards — those were beasts. Both CGA and EGA sort of withered when the 1990s arrived.

According to [David]’s research, CGA monitors continued to be used for some time even after EGA was introduced — primarily because of cost. It might cost you $400 to get an ATI EGA Wonder card, and that or more for an EGA monitor. Many folks just upgraded the card first, and took advantage of the fact that the EGA Wonder could drive CGA monitors.

If you are interested in the history and technology of these old cards, check out our coverage from 2016 where [David] does a deep dive into CGA cards and discusses, among other things, the CGA composite video mode.

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NERF – Neural Radiance Fields

November 30, 2022 by Anne Ogborn 17 Comments

Making narrative film just keeps getting easier. What once took a studio is now within reach of the dedicated hobbyist. And Neural Radiance Fields are making it a dramatic step easier. The guys from [Corridor Crew] give an early peek.

Filming and editing have reached the cell phone and laptop stage of easy. But sets, costumes, actors, lighting, and so on haven’t gotten substantially cheaper, and making your own short film is still a major project.

Enter 3D graphics. With a good gaming laptop, anybody can make a photorealistic scene in Blender and place live action actors in it. But it takes both a lot of skill and work. And often, the scene you’re making is available as a real place, but you can’t get permission to film or haul actors, props, crew, and so on to the set.

A new technology, NERF, for “NEural Radiance Fields”, has decreased the headaches a lot. Instead of making a 3D model of the scene and using that to predict what reaches the camera, the software starts with video of the scene and machine learns a “radiance field” – a model of how light is reflected by the scene. Continue reading “NERF – Neural Radiance Fields” →

At A Loss For Words? Try A Teleprompter

November 19, 2022 by Al Williams 24 Comments

With everyone doing videos these days, you might want to up your narration game with a teleprompter. [Modern Hobbyist] can help. Since he does videos — like the one about the teleprompter below — we assume he built it out of his own need for the device. Actually, this is his second teleprompter. The first one was larger and not battery-powered, so this new version offers more portability. The camera shoots through the teleprompter screen so you can look right at the camera and still stay on script.

The project reuses some of the original teleprompter code, showing a text file via a Raspberry Pi. There’s also a control keyboard that lets you remotely control the scrolling speed. The real key to this project though is the 3D printed housing. Well, that and the reflective glass screen. Given that, you could do the actual text display in a number of ways.

Apparently, the portability of the build is limited somewhat by the weight of the camera. You could, of course, use something lighter or perhaps add some weight opposite to at least balance it a bit. The 3D printing files are on Thingiverse and the rest is on GitHub, so you can easily make changes if you want.

You would think we would see more teleprompter projects, and we do see some. We’ve also seen a hack to let you look through your laptop screen on video conferences.

Continue reading “At A Loss For Words? Try A Teleprompter” →