A Pedal Powered Cinema

When the apocalypse hits and your power goes out, how are you going to keep yourself entertained? If you are lucky enough to be friends with [stopsendingmejunk], you can just hop on his pedal powered cinema and watch whatever movies you have stored on digital media.

This unit is built around an ordinary bicycle. A friction drive is used to generate the electricity via pedal power. In order to accomplish this, a custom steel stand was fabricated together in order to lift the rear wheel off the ground. A 24V 200W motor is used as the generator. [stopsendingmejunk] manufactured a custom spindle for the motor shaft. The spindle is made from a skateboard wheel. The motor is mounted in such a way that it can be lowered to rub the skateboard wheel against the bicycle wheel. This way when the rear bicycle wheel spins, it also rotates the motor. The motor can be lifted out of the way when cruising around if desired.

The power generated from the motor first runs through a regulator. This takes the variable voltage from the generator and smooths it out to a nice even power signal. This regulated power then charges two Goal Zero Sherpa 100 lithium batteries. The batteries allow for a buffer to allow the movie to continue playing while changing riders. The batteries then power the Optomo 750 projector as well as a set of speakers.

FPGA Based Ambilight Clone

The Philips Ambilight – a bunch of rear-facing RGB LEDs taped to the back of a TV – is becoming the standard project for anyone beginning to tinker with FPGAs. [DrX]’s is the best one we’ve seen yet, with a single board that reads and HDMI stream, makes blinkey lights go, and outputs the HDMI stream to the TV or monitor.

[DrX] is using an FPGA development board with two HDMI connectors – the Scarab miniSpartan6+ – and a strand of WS2801 individually addressable RGB LEDs for this project. With a bit of level shifting, driving the LEDs was easily taken care of. But what about decoding HDMI?

Most of the project is borrowed from a project that displays a logo in the corner of a 720p video stream. The hardware is the same, but for an Ambilight clone, you need to read the video stream and process it, not just write to it. By carefully keeping track of the R, G, and B values for each pixel along with the pixel clock,  the colors along the edge of a display can be averaged. It’s not as difficult or as memory-intensive as building a frame buffer; nearly all of the picture data is thrown out when assembling the averages around the perimeter of the display. It does work, though.

After figuring out the average color around the perimeter of the display, it’s just a simple matter of driving the LEDs. Tape those LEDs to the back of a TV, and there’s an Ambilight clone, made with an FPGA.

[DrX] has a few videos of his project in action. You can check those out below.

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A Non-Infinite But Arbitrariliy Large Number of Video Feeds

It’s pretty common to grab a USB webcam when you need something monitored. They’re quick and easy now, most are plug-and-play on almost every modern OS, and they’re cheap. But what happens when you need to monitor more than a few things? Often this means lots of cameras and additional expensive hardware to support the powerful software needed, but [moritz simon geist] and his group’s Madcam software can now do the same thing inexpensively and simply.

Many approaches were considered before the group settled on using PCI to handle the video feeds. Obviously using just USB would cause a bottleneck, but they also found that Ethernet had a very high latency as well. They also tried mixing the video feeds from Raspberry Pis, without much success either. Their computer is a pretty standard AMD with 4 GB of RAM running Xubuntu as well, so as long as you have the PCI slots needed there’s pretty much no limit to what you could do with this software.

At first we scoffed at the price tag of around $500 (including the computer that runs the software) but apparently the sky’s the limit for how much you could spend on a commercial system, so this is actually quite the reduction in cost. Odds are you have a desktop computer anyway, and once you get the software from their Github repository you’re pretty much on your way. So far the creators have tested the software with 10 cameras, but it could be expanded to handle more. It would be even cooler if you could somehow incorporate video feeds from radio sources!

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A Laptop with an External Graphics Card?

It used to be that desktop computers reigned king in the world of powerful computing, and to some extent, they still do. But laptops are pretty powerful these days, and in our experience, a lot of engineering companies have actually swapped over to them for resource hungry 3D CAD applications — But what if you still need a bit more power?

Well, [Kamueone] wasn’t satisfied with the performance of his Razer Blade GTX870m laptop, so he decided to hack it and give it its own external graphics card.

Now unfortunately this really isn’t quite a simple as running some PCIE extender cables — nope. You’ll have to modify the BIOS first, which according to [Kamueone], isn’t that bad. But after that’s done you’ll also need a way to mount your graphics card outside of the laptop. He’s using an EXP GDC Beast V6 which uses a mini PCIE cable that can be connected directly to the laptop motherboard. You’re also going to need an external power supply.

[Kamueone] ran some benchmarks and upgrading from the stock onboard GTX870m to an external GTX 780ti resulted in over three times the frame rate capability — 40fps stock, 130fps upgraded!

Digital Light Processing, So Many Tiny Mirrors

Did you know there are a million little mirrors flickering back and forth, reflecting light within some modern projectors; like a flip-dot display but at the micro level? In his video, [Ben Krasnow] explains the tiny magic at work in DLP, or digital light processing technology with a scaled up model he constructed of the moving parts.

LCD projectors work much like old slide projectors. Light is shined through a transparent screen containing the image, which is then focused and enlarged through a lens. DLP projectors however achieve the moving image in a slightly different way. A beam of focused light is shined onto a chip equipped with an array of astonishingly small mirrors. When the mirror is flipped in one direction, it reflects the light out through the lens and creates a visible pixel. When the mirror is tilted the opposite direction, no light is reflected and the pixel is dark. All of these tiny moving parts are actuated by means of static electricity, and since a pixel can effectively only either be in an on or off state without any range of value in-between, the pixel must flutter at a rate fast enough to achieve the illusion of intensity, much like pulsing an LED to create a dimming effect.

In addition to slicing open the protective casing of one of these tiny micro-mirrored chips to give us a look at their physical surface under a microscope, [Ben] also built his own functioning matrix from tiles of mirrors and metal washers sandwiched around pieces of string. A wound electromagnet positioned behind each tile tilts the pixel into position when a current is run through the wire — although he didn’t sink the time needed to build out the full array in this manner (and we don’t blame him). If you do have the time and add in a high powered flash-light, this makes for an awesome way to shine messages on your roommate’s wall.

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Nerdalert: German TV Producers’ Amazing Vectorscope Animations

German weekend late-night comedy show “Neo Magazin Royale” has a bunch of super-nerds behind the screens in the production studio. This is apparently what they do when they’re (not) working: making test screens that render as multiple animations on their test equipment.

While others out there are limited to displaying cool graphics on oscilloscopes, these guys have vectorscopes and waveformer monitors. A vectorscope is like an oscilloscope in X-Y mode, but with one screen that decodes the color space and one screen for the audio (in stereo). A waveform monitor that plots out the brightness levels of a test image. Normal studio techs use these to calibrate their colors, brightness, and audio levels.

Apparently, these guys programmed a custom test screen that would: a) encode a small animation of a 20-sided die spinning around the show’s logo in the color channel b) encode the show’s logo in the left and right sound channels, and c) their production company’s logo in the screen’s brightness.

At the end of the video, the director Patrick (in the glasses) admits that they’ve spent about three months working on this project and everyone starts laughing. “And who gets anything from this? Nobody!” says the show’s host.

One way to rectify that, though. Post the source code!

[darNES] Stores Cached Netflix on NES Cartridge

Let’s play a quick word association game: Peanut butter…jelly. Arches…golden. NES…Netflix?  That last one sounds like a stretch, but the [darNES] development team had a Hack Day and a dream.  They started with cached Netflix data and ended up playing it on an ordinary NES. (YouTube link)

The data was pre-converted so that the video frames were stored as tilesets and stored in the ROM image. [Guy] used the NES memory mapper (MMC3) to swap the frames. [darNES] had originally planned to use a Raspberry Pi in the cartridge to handle the video conversion and networking, but had to change gears and make a static ROM image due to time constraints and resource availability.

Accessing the Netflix data is just like the days of yore – load the cartridge into an unmodified NES and hit the power button (they didn’t even need to blow on it!). A bare-bones Netflix gallery appears. You can move the white cursor on the screen with the NES controller’s D-pad. House of Cards was the choice, and true to form, the next screen shows you a synopsis with a still image and gives you the option to Play. Recommend is also there, but obviously won’t work in this setup. Still, it got a chuckle out of us. [darNES] admits that due to time issues they did not optimize the color palette for the tilesets. They plan to release more of the technical info this week, but have already given us some hints on their Hacker News thread.

Check out the videos after the break to see the video they fit onto a 256K NES cartridge.

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