DIY Planetarium Built From PVC Pipes And Cardboard

March 12, 2018 by Tom Nardi 9 Comments

When you think about DIY projects, you probably don’t consider building your own planetarium. Why would you? Building the thing is surely outside the capabilities of the individual, and even if you could figure it out, the materials would be far too expensive. There’s a limit to DIY projects, and obviously building a planetarium is on the wrong side of the line. Right?

Well, apparently not. [Gabby LeBeau] has documented the planetarium she built as her senior project, and if you’ll forgive the pun, it’s absolutely out of this world. Using readily available parts and the help of family and friends, she built a fully functional planetarium big enough to seat the Physics Department. No word on what grade she got, but it’s a safe bet she screwed the curve up for the rest of the class.

After two months of research and a couple of smaller proof of concept builds, she was able to find a business who graciously allowed her to construct the full scale planetarium in their warehouse. The frame is made of PVC pipes held together with zip ties. The big advantage to using the PVC pipes (beyond being cheap and easy to works with) is that they will automatically find a hemispherical shape when bent; saving the time and trouble it would take to create the shape with more rigid building materials.

Once the PVC frame was up, white cardboard panels were cut to shape and attached to the inside. The panels were lined up as closely as possible, but gaps were covered with white tape so the fit didn’t need to be perfect. When the dome was finished, it was lifted and placed on metal trusses to get some room underneath, and finally covered with a black tarp and stage curtain to block out all light.

Of course, she didn’t go through all this trouble to just stick some glow in the dark stars on the inside of this thing. The image from a standard projector is directed at a flat mirror, which then bounces off of a convex mirror. Driving the projector is a laptop running Stellarium. While there were some imperfections she couldn’t get polished or cleaned off of the mirrors, the end result was still very impressive.

Unfortunately, you can’t really do a planetarium justice with a camera, so we aren’t able to see what the final image looked like. But judging by the slack-jawed faces of those who are pictured inside of it, we’re going to go out on a limb and say it was awesome.

We might suggest trying to quiet down the projector or adding some lasers to the mix, but overall this is a truly exceptional project, and we’re jealous of everyone who got to experience it first hand.

One Man’s Quest For A Desktop Spherical Display

March 5, 2018 by Tom Nardi 20 Comments

[Nirav Patel] is a man on a mission. Since 2011 he has been obsessed with owning a spherical display, the kind of thing you see in museums and science centers, but on a desktop scale. Unfortunately for him, there hasn’t been much commercial interest in this sort of thing as of yet. Up to this point, he’s been forced to hack up his own versions of his dream display.

That is until he heard about the Gakken Worldeye from Japan. This device promised to be exactly what he’s been looking for all these years, and he quickly snapped up two of them: one to use, and one to tear apart. We like this guy’s style. But as is often the case with cheap overseas imports, the device didn’t quite live up to his expectations. Undaunted by the out of the box performance of the Worldeye, [Nirav] has started documenting his attempts to improve on the product.

These displays work by projecting an image on the inside of a frosted glass or plastic sphere, and [Nirav] notes that the projection sphere on the Worldeye is actually pretty decent. The problem is the electronics, namely the anemic VGA resolution projector that’s further cropped down to a 480 pixel circle by the optics. Combined with the low-quality downsampling that squashes down the HDMI input, the final image on the Worldeye is underwhelming to say the least.

[Nirav] decided to rip the original projector out of the Worldeye and replace it with a Sony MP-CL1 model capable of a much more respectable 1280×720. He came up with a 3D printed bracket to hold the MP-CL1 in place, and has put the files up on Thingiverse for anyone who might want to play along at home. The results are better, but unfortunately still not great. [Nirav] thinks the sphere is physically too small to support the higher resolution of the MP-CL1, plus the optics aren’t exactly of the highest quality to begin with. But he’s just glad he didn’t have to build this one from scratch.

Going back to our first coverage of his DIY spherical display in 2012, we have to say his earliest attempts are still very impressive. It looks like this is a case of the commercial market struggling to keep up with the work of independent hackers.

FPGA Makes ASCII Video

March 5, 2018 by Al Williams 28 Comments

Human beings like pictures which is probably why there’s the old adage “A picture’s worth a thousand words.” We take computer graphic output for granted now, but even in the earliest days for Teletypes and line printers, there was artwork made from characters ranging from Snoopy to Spock. [Wenting Z] continues the tradition by creating an FPGA that converts VGA video to ASCII art and outputs it via DVI.

The device uses a Xilinx Virtex device and uses about 500 LUT (look up tables) which is not much at all. You can see a video (that includes an overlay of the source video) of the device in action below.

In fact, we think of art like this as a computer phenomenon, but [Flora Stacey] created a butterfly on a typewriter in 1898 and ham radio operators were doing art using paper tape for the last half of the twentieth century. Even before that, In 1865, Alice in Wonderland had a certain passage that was typeset to suggest a mouse’s tail. Perhaps the pinnacle is the famous ASCII version of Star Wars.

This is decidedly less mechanical than some of the other ASCII art projects we’ve seen. If you have a taste for more text art, have a look at some other examples, including a very old advertisement that uses character art.

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Software Defined Television On An ESP32

February 22, 2018 by Dan Maloney 24 Comments

Composite video from a single-board computer? Big deal — every generation of Raspberry Pi has had some way of getting composite signals out and onto the retro monitor of your choice. But composite video from an ESP32? That’s a thing now too.

There are some limitations, of course, not least of which is finding a monitor that can accept a composite input, but since [bitluni]’s hack uses zero additional components, we can overlook those. It really is as simple as hooking the monitor up to pin 25 and ground because, like his recent ESP32 AM radio station, the magic is entirely in software. For video, [bitluni] again uses his I²S tweaks to push a lot of data into the DAC really fast, reproducing the sync and image signals in the 0-1 volt range of the PAL composite standard. His code also supports the NTSC standard, but alas because of frequency limitations in the hardware it’s monochrome only for both standards, at least for now. He’s also got a neat trick to improve performance by running the video signal generation and the 3D-rendering on separate cores in the ESP32. Check out the results in the video below.

It looks like the ESP32 is getting to be one of those “Is there anything it can’t do?” systems. Aside from radio and video, we’ve seen audio playback, vector graphics, and even a Basic interpreter easter egg.

Continue reading “Software Defined Television On An ESP32” →

Chasing The Electron Beam At 380,000 FPS

January 29, 2018 by Adam Fabio 20 Comments

Analog TV is dead, but that doesn’t make it any less awesome. [Gavin and Dan], aka The Slow Mo Guys recently posted a video about television screens. Since they have some incredible high-speed cameras at their disposal, we get to see the screens being drawn, both on CRT and more modern LCD televisions.

Now we all know that CRTs draw one pixel at a time, drawing from left to right, top to bottom. You can capture this with a regular still camera at a high shutter speed. The light from a TV screen comes from a phosphor coating painted on the inside of the glass screen. Phosphor glows for some time after it is excited, but how long exactly? [Gavin and Dan’s] high framerate camera let them observe the phosphor staying illuminated for only about 6 lines before it started to fade away. You can see this effect at a relatively mundane 2500 FPS.

Cranking things up to 380,117 FPS, the highest speed ever recorded by the duo, we see even more amazing results. Even at this speed, quite a few “pixels” are drawn each frame. [Gavin] illustrates that by showing how Super Mario’s mustache is drawn in less than one frame of slow-mo footage. You would have to go several times faster to actually freeze the electron beam. We think it’s amazing that such high-speed analog electronics were invented and perfected decades ago.

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Know Your Video Waveform

January 18, 2018 by Jenny List 84 Comments

When you acquired your first oscilloscope, what were the first waveforms you had a look at with it? The calibration output, and maybe your signal generator. Then if you are like me, you probably went hunting round your bench to find a more interesting waveform or two. In my case that led me to a TV tuner and IF strip, and my first glimpse of a video signal.

An analogue video signal may be something that is a little less ubiquitous in these days of LCD screens and HDMI connectors, but it remains a fascinating subject and one whose intricacies are still worthwhile knowing. Perhaps your desktop computer no longer drives a composite monitor, but a video signal is still a handy way to add a display to many low-powered microcontroller boards. When you see Arduinos and ESP8266s producing colour composite video on hardware never intended for the purpose you may begin to understand why an in-depth knowledge of a video waveform can be useful to have.

The purpose of a video signal is to both convey the picture information in the form of luminiance and chrominance (light & dark, and colour), and all the information required to keep the display in complete synchronisation with the source. It must do this with accurate and consistent timing, and because it is a technology with roots in the early 20th century all the information it contains must be retrievable with the consumer electronic components of that time.

We’ll now take a look at the waveform and in particular its timing in detail, and try to convey some of its ways. You will be aware that there are different TV systems such as PAL and NTSC which each have their own tightly-defined timings, however for most of this article we will be treating all systems as more-or-less identical because they work in a sufficiently similar manner.

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Raspberry Pi Offers Soulless Work Oversight

January 15, 2018 by Tom Nardi 8 Comments

If you’re like us, you spend more time than you care to admit staring at a computer screen. Whether it’s trying to find the right words for a blog post or troubleshooting some code, the end result is the same: an otherwise normally functioning human being is reduced to a slack-jawed zombie. Wouldn’t it be nice to be able to quantify just how much of your life is being wasted basking in the flickering glow of your monitor? Surely that wouldn’t be a crushingly depressing piece of information to have at the end of the week.

With the magic of modern technology, you need wonder no longer. Prolific hacker [dekuNukem] has created the aptly named “facepunch”, which allows you to “punch in” with nothing more than your face. Just sit down in front of your Raspberry Pi’s camera, and the numbers start ticking away. It’s like the little clock in the front of a taxi: except at the end you don’t have to pay anyone, you just have to come to terms with what your life has become. So that’s cool.

It doesn’t take much hardware to play along at home. All you need is a Raspberry Pi and the official camera accessory. Though for the full effect you should add one of the displays supported by the Luma.OLED driver so you can see the minutes and hours ticking away in real-time.

To get the facial recognition going, all you need to do is take a well-lit picture of your face and save it as a 400×400 JPEG. The Python 3 script will take care of the rest: checking the frames from the camera every few seconds to see if your beautiful mug is in the frame, and incrementing the counters accordingly.

Even if you’re not in the market for an Orwellian electronic supervisor, this project is a great example to get you started in the world of facial recognition. With a little luck, you’ll be weaponizing it in no time.