Deflecting Earthquakes The Way Ancient Romans Did It

A recent French study indicates that the ancient Romans may have figured out how to deal with earthquakes by simply deflecting the energy of the waves using structures that resemble metamaterials. These are materials which can manipulate waves (electromagnetic or otherwise) in ways which are normally deemed impossible, such as guiding light around an object using a special pattern.

In a 2012 study, the same researchers found that a pattern of 5 meter deep bore holes in the ground was effective at deflecting a significant part of artificially generated acoustic waves. One of the researchers, [Stéphane Brûlé], noticed on an aerial photograph of a Gallo-Roman theater near the town of Autun in central France that its pattern of pillars bore an uncanny resemblance to this earlier experiment: a series of concentric (semi) circles with the distance between the pillars (or holes) decreasing nearer the center.

Further research using archaeological data of this theater site confirmed that it did appear to match up the expected pattern if one would have aimed to design a structure that could successfully deflect the acoustic energy from an earthquake. This raises the interesting question of whether this was a deliberate design choice, or just coincidence.

Additional research on the Colosseum in Rome and various other amphitheaters did however turn up the same pattern, which makes it seem like a deliberate choice by the Roman builders over a long period of time. With this pattern apparently capable of protecting a structure from the destructive effects of the acoustic waves generated by an earthquake, the remaining question is whether they discovered this pattern over time by observing damage to buildings and decided to implement it in new buildings.

Although we’ll likely never get an answer to that question, this discovery can however lead to improvements to individual buildings today, as well as entire cities, that may protect them against earthquakes and save countless lives that way.

The Kalman Filter Exposed

If we are hiring someone such as a carpenter or an auto mechanic, we always look for two things: what kind of tools they have and what they do when things go wrong. For many types of embedded systems, one important tool that serious developers use is the Kalman filter. It is also something you use when things go “wrong.” [Carcano] recently posted a tutorial on Kalman filter equations that tries to demystify the topic. His example — a case of things going wrong — is when you have a robot that knows how far it is supposed to move and also has GPS coordinates of its positions. Since the positions probably don’t agree, you can consider that a problem with the system.

The obvious answer is to average the two positions. That’s fine if the error is small. But a Kalman filter is much more robust in more situations. [Carcano] does a good job of taking you through the math, but we will warn you it is plenty of math. If you don’t know what a Gaussian distribution is or the word covariance makes you think of sailboats, you are going to have to do some reading to get through the post.

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The Clickiest Game Of Tetris You’ll Ever Play, On A Flip-Dot

Like many other classics it’s easy to come up with ways to ruin Tetris, but hard to think of anything that will make it better. Adding more clickiness is definitely one way to improve the game, and playing Tetris on a flip-dot display certainly manages to achieve that.

The surplus flip-dot display [sinowin] used for this version of Tetris is a bit of an odd bird that needed some reverse engineering to be put to work. The display is a 7 x 30 matrix with small dots, plus a tiny green LED for each dot. Those LEDs turned out to be quite useful for replicating the flashing effect used in the original game when a row of blocks was completed, and the sound of the dots being flipped provides audio feedback. The game runs on a Teensy through a custom driver board and uses a Playstation joystick for control. The video below, in perfectly acceptable vertical format, shows the game in action and really makes us want to build our own, perhaps with a larger and even clickier flip-dot display.

The best thing about Tetris is its simplicity: simple graphics, simple controls, and simple gameplay. It’s so simple it can be played anywhere, from a smartwatch to a business card and even on a transistor tester.

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Turn Your Car Into A Simulator

Video games, while entertaining to be sure, are a great way to experience things that could not easily be recreated in real life. Shooting aliens on a giant ring in space is an obvious example, but there are some more realistic examples that video games make much more accessible, such as driving a race car. You can make that experience as realistic as you want, too, and can even go as far as using a real car as your controller.

All modern cars use a communication system to allow their various modules to talk to one another. Fuel injection, throttle position, pedal positions, steering wheel angle, and climate control systems can all communicate on the CAN bus, and by tapping into that information the car can be used as a controller for a video game. Once you plug in to the OBD-II port on a car, you’ll need a piece of software to decode all of that information. [Andrew] uses uinput, a tool that allows Linux machines to take any input signal and map it in any way that can be programmed.

The build also includes the use of an integrated pico projector, allowing the car to be parked and turned into a simulator at any time. It’s similar to another project which used a Mazda instead of a Chevrolet Volt, but it just goes to show how straightforward it can be to take information from the CAN bus of a modern car.

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A Full-Stack Web Browser

Interviewing to be a full-stack engineer is hard. It’s a lot harder than applying for a junior dev job where you’re asked to traverse a red-black tree on a whiteboard. For the full-stack job, they just give you a pile of 2N2222 transistors. (The first company wasn’t a great fit, and I eventually found a place that gave me some 2N2907s for the interview.) That said, there’s a certain challenge in seeing how far you can push some doped silicon. Case in point, [Alastair Hewitt]. He’s building a computer to browse the world wide web from the gate level up.

The goal of this project is to browse the web using only TTL logic. This presents problems that aren’t readily apparent at first glance. First up is being able to display text on a screen. The easiest way to do this now is to get a whole bunch of modern memories that are astonishingly fast for a 1970s vintage computer. This allows for VGA output, and yes, we’ve seen plenty of builds that output VGA using some big honkin’ memories. It turns out these RAM and ROM chips are a little better than the specs say they are, and this computer is overclocked from the very beginning.

A bigger problem is how to interface with a network. This is a problem for very old computers, but PPP still exists and if you have the software stack you can read something from a server over a serial connection. [Alistar] actually found the UART frequency was more important than the dot clock frequency of VGA, and the system clock must therefore be built around the serial port, not the display interface. This means the text mode interface is actually 96 columns instead of the usual 80 columns.

It’s very easy to say that you’re building a computer on a bread board. It’s another thing entirely to actually do it. This is actually a surprisingly well-though out sketch of a computer system that will, theoretically, be able to connect to the Internet. Of course, the reality of the situation is that this computer will be connecting over serial to a computer that’s connected to the Internet, but there’s no shame in that. You can check out the progress on the GitHub for this project.

The Amazing New World Of Gallium Nitride

From the heart of Silicon Valley comes a new buzzword. Gallium nitride is the future of power technology. Tech blogs are touting gallium nitride as the silicon of the future, and you are savvy enough to get in on the ground floor. Knowing how important gallium nitride is makes you a smarter, better consumer. You are at the forefront of your peer group because you know of an up and coming technology, and this one goes by the name of gallium nitride.

OK, gallium nitride is more than just a buzzword. It is, indeed, important materials science. Gallium nitride is a semiconductor that allows for smaller electronics, more powerful electric cars, better solar cells, and is the foundation of all LED lighting solutions today. Time will tell, but it may well mark a revolution in semiconductors. Here’s what you need to know about it now.

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Your Masterclass in Product Design: Hackaday Prize Mentor Sessions

New to this year’s Hackaday Prize is a set of live mentor sessions and you’re invited! Being at the center of a successful product design project means having an intuitive sense in many, many areas; from industrial design and product packaging, to manufacturing and marketing. This is your chance to learn from those experts who have already been there and want to make your experience better and easier.

We want you to get involved by entering your own project into the Hackaday Prize; now is the time to tell us you’re ready to demo your project with a mentor. Hackaday Prize Mentor Sessions are happening every two weeks throughout the summer. In these video chats we’re inviting some promising Hackaday Prize entries to start off with a “demo day” type of presentation, followed by an interactive session with the mentor hosting each event.

It’s also important that this incredible resource be available to all, so these videos will be published once the mentor session wraps up. This is a master class format where the advice and shared experience have a beneficial effect far beyond the groups sharing their projects.

The 2019 Hackaday Prize focuses on product development. Show your path from an idea to a product design ready for manufacturing and you’ll be on target to share in more than $200,000 in cash prizes!

Meet Some of Our Mentors:

Below you will find just a taste of the mentor sessions in the works. These are the first three mentor session videos that will be published, but make sure you browse the full set of incredible mentors and get excited for what is to come!

Bunnie Huang

Co-founder, Chibitronics


Bunnie is best known for his work hacking the Microsoft Xbox, as well as
his efforts in designing and manufacturing open source hardware. His past projects include the chumby (app-playing alarm clock), Chibitronics (peel-and-stick electronics for crafting), and the Novena (DIY laptop). He currently lives in Singapore where he runs a private product design studio, Kosagi, and actively mentors several startups and students of the MIT Media Lab.

Mattias Gunneras & Andrew Zolty

Co-founders, BREAKFAST NY


Zolty and Mattias founded BREAKFAST in 2009. This studio of multidisciplinary artists and engineers conceives, designs, and fabricates high-tech contemporary art installations and sculptures. BREAKFAST has over 15 large-scale pieces that can be found in various museums, arenas, and lobby spaces throughout the world.

Giovanni Salinas

Product Development Engineer, DesignLab


Giovanni is the Product Development Engineer at Supplyframe DesignLab. He has designed and developed hundreds of products, including consumer electronics, kitchenware, and urban furniture for the North American, European, Chinese and Latin American markets. Through his experience he has honed his expertise in rapid prototyping and DFM in plastics, wood, and metals.

We Want You To Demo Your Product!

Mentor sessions will continue throughout the summer with these and other mentors! Sign up to demo your 2019 Hackaday Prize entry!