Hackaday Podcast 135: Three Rocket Hacks, All The Game Boy Gates, And Depth Sounding From A Rowboat

September 10, 2021 by 11 Comments

Hackaday editors Mike Szczys and Tom Nardi go over the best stories and hacks from the previous week, covering everything from sidestepping rockets to homebrew OLED displays. We’ll cover an incredible attempt to really emulate the Nintendo Game Boy, low-cost injection molding of rubbery parts, a tube full of hypersonic shockwaves, and how a hacked depth finder and a rowboat can help chart those local rivers and lakes that usually don’t get any bathymetric love. Plus, even though he’s on vacation this week, Elliot has left us with a ruddy mysterious song to try and identify.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

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Creating Video From A ROM

September 10, 2021 by 14 Comments

We’re used to computers with display screens, yet how many of us have created the circuitry to drive one directly? Sure, we’ve coded up an SPI display driver on a microcontroller, but create the hardware to generate a usable video signal? That’s a little more difficult. [Jdh] has given it a go though, with a TTL video card.

In this case it’s not a card so much as a collection of breadboards, but all the logic is there to generate the complex array of video timings necessary for synchronisation, and to output the bits sequentially at the right voltage levels for the analogue monitor. It’s worth pointing out though that it’s not a composite video signal that’s being created sinceit’s monochrome only with no subcarrier.

In the end he encounters the problem that his ROM isn’t fast enough for the pixel rate and thus the image has artefacts, but it does at least produce a recognisable and readable something on the screen. Old hands in the video business might point out that analogue TVs were a bit forgiving when it came to exact timings and line counts so the circuit could quite possibly be simplified, and also that trading away some of the resolution might fix the ROM speed issue. But it’s an impressive piece of work, and should be of particular interest for anyone interested in how video works.

Fans of video cards on breadboards should also check out [Ben Eater’s] 7400-series video card.

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This Week In Security: Ghoscript In Imagemagick, Solarwinds, And DHCP Shenanigans

September 10, 2021 by 3 Comments

A PoC was just published for a potentially serious flaw in the Ghostscript interpreter. Ghostscript can load Postscript, PDF, and SVG, and it has a feature from Postscript that has been a continual security issue: the %pipe% command. This command requests the interpreter to spawn a new process — It’s RCE as part of the spec. This is obviously a problem for untrusted images and documents, and Ghostscript has fixed security vulnerabilities around this mis-feature several times over the years.

This particular vulnerability was discovered by [Emil Lerner], and described at ZeroNights X. That talk is available, but in Russian. The issue seems to be a bypass of sorts, where the pipe command appears to be working in the /tmp/ directory, but a simple semicolon allows for an arbitrary command to be executed. Now why is this a big deal? Because ImageMagick uses Ghostscript to open SVG images by default on some distributions, and ImageMagick is often used for automatically resizing and converting images for web sites. In [Emil]’s presentation, he uses this flaw as part of an attack chain against three different companies.

I was unable to reproduce the flaw on my Fedora install, but I haven’t found any notice of it being fixed in the Ghostscript or Imagemagick changelogs either. It’s unclear if this problem has already been fixed, or if this is a true 0-day for some platforms. Either way, expect attackers to start trying to make use of it.

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An acousto-optic tunable filter and laser

Acousto-Optic Filter Uses Sound To Bend Light

September 10, 2021 by 17 Comments

We all know that light and sound are wave phenomena, but of very different kinds. Light is electromechanical in nature, while sound is mechanical. Light can travel through a vacuum, while sound needs some sort of medium to transmit it. So it would seem that it might be difficult to use sound to modify light, but with the right equipment, it’s actually pretty easy.

Easy, perhaps, if you’re used to slinging lasers around and terms like “acousto-optic tunable filter” fall trippingly from your tongue, as is the case for [Les Wright]. An AOTF is a device that takes a radio frequency input and applies it to a piezoelectric transducer that’s bonded to a crystal of tellurium oxide. The RF signal excites the transducer, which vibrates the TeO2 crystal and sets up a standing wave within it. The alternating bands of compressed and expanded material within the crystal act like a diffraction grating. Change the excitation frequency, and the filter’s frequency changes too.

To explore the way sound can bend light, [Les] picked up a commercial AOTF from the surplus market. Sadly, it didn’t come with the RF driver, but no matter — a few quick eBay purchases put the needed RF generator and power amplifier on his bench. The modules went into an enclosure to make the driver more of an instrument and less of a one-off, with a nice multi-turn pot and vernier knob for precise filter adjustment. It’s really kind of cool to watch the output beam change colors at the twist of a knob, and cooler still to realize how it all works.

We’ve been seeing a lot of [Les]’ optics projects lately, from homemade TEA lasers to blasting the Bayer filter off a digital camera, each as impressive as the last! Continue reading “Acousto-Optic Filter Uses Sound To Bend Light” →

Putting Thousands Of Minecraft Players On The Same Server

September 10, 2021 by 15 Comments

Multi-threading was the common go-to technique for extracting more performance from a machine for several years. These days it’s all about horizontal scaling or adding more virtual machines to a pool of workers. The Minecraft server is still stuck in the past in some ways as it supports neither multi-threading nor horizontal scaling. [Jackson Roberts] decided to change all that by hacking Minecraft to support thousands of players rather than dozens.

Since the server is single-threaded, having more than 100 players on a single server can slow it to a crawl. Some mods try to optimize and speed up the existing server but [Jackson] wanted more. An early proof of concept was to slice the world into separate servers, each holding 64×64 chunks (chunks are what Minecraft defines as a 16x256x16 volume of the world). When crossing a boundary, entities such as players and zombies were transferred from one server to another. While workable, the demo had issues such as parts of the world being inaccessible if a server went down. The boundaries were also jarring as you had to reconnect and couldn’t see players outside your server.

Instead of splitting the world, [Jackson] took the approach to split the players and have some backing store for persisting and broadcasting changes. A proxy sits in front of several Minecraft servers, which each have a connection to a WorldQL server (a spatial database based on Postgres). Each server reports the player’s location to the WorldQL server and receives updates for their loaded locations. When a server comes online, it catches up with the changes stored in WorldQL and starts syncing, allowing servers to auto-scale. There are still a few core game mechanics that aren’t quite ready for prime-time such as NPCs and Redstone, but the progress so far is remarkable.

The code for the Minecraft plugin is up on GitHub, but more is coming in the future. So if you’re interested in something a little more vanilla, why not marvel at the completely playable Pokemon Red inside vanilla Minecraft?

CAD design for a vinyl record cutter.

VinyGo Stereo Vinyl Recorder Will Put You In The Groove

September 9, 2021 by 30 Comments

A long time ago, there were these vinyl recording booths. You could go in there and cut a 45PM record as easily as getting a strip of four pictures of yourself in the next booth along the boardwalk. With their 2021 Hackaday Prize entry called VinyGo, [mras2an] seeks to reinvigorate this concept for private use by musicians, artists, or anyone else who has always wanted to cut their own vinyl.

VinyGo is for people looking to make a few dozen copies or fewer. Apparently there’s a polymer shortage right now on top of everything else, and smaller clients are getting the shaft from record-pressing companies. This way, people can cut their own records for about $4 a unit on top of the cost of building VinyGo, which is meant to be both affordable and accessible.

You probably know how a record player works, but how about a record cutter? As [mras2an] explains over on IO, music coming through a pair of speakers vibrates a diamond cutting head, which cuts a groove in the vinyl that’s an exact representation of the music. Once it’s been cut, a regular stylus picks up the groove and plays back the vibrations. Check it out after the break.

[mras2an] plans to enter VinyGo into the Hackaday Prize during the Wildcard round, where anything goes. Does your project defy categorization? Or are you just running a little behind? The Wildcard round runs from Monday, September 27th to Wednesday, October 27th and is your last chance to enter this year’s Prize.

Not your kind of vinyl cutter? We’ve got those, too.

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Buoyant Aero MK4 keeps station in a tail wind

Aerodynamic Buoyant Blimp Budges Into Low Cost Cargo Commerce

September 9, 2021 by 22 Comments

Before the Wright Brothers powered their way across the sands of Kitty Hawk or Otto Lilienthal soared from the hills of Germany, enveloping hot air in a balloon was the only way to fly. Concepts were refined as time went by, and culminated in the grand Zeppelins of the 1930’s. However since the tragic end of the Zeppelin era, lighter than air aircraft have often been viewed as a novelty in the aviation world.

Several companies have come forward in the last decade, pitching enormous lighter than air machines for hauling large amounts of cargo at reduced cost. These behemoths rely on a mixture of natural buoyancy and lifting body designs and are intended to augment ferries and short haul commercial aviation routes.

It was this landscape where Buoyant Aero founders [Ben] and [Joe] saw an underserved that they believe they can thrive in: Transporting 300-600 lbs between warehouses or airports. They aim to increase the safety, cargo capacity, and range of traditional quadcopter concepts, and halve the operating costs of a typical Cessna 182. They hope to help people such as those rural areas of Alaska where high transportation costs double the grocery bill.

Like larger designs, Buoyant Aero’s hybrid airship relies on aerodynamic lift to supply one third the needed lift. Such an arrangement eliminates the need for ballast when empty while retaining the handling and navigation characteristics needed for autonomous flight. The smaller scale prototype’s outstanding ability to maneuver sharply and hold station with a tailwind is displayed in the video below the break. You can also learn more about their project on their Hacker News launch. We look forward to seeing the larger prototypes as they are released!

Perhaps this project will inspire your own miniature airship, in which case you may want to check out the Blimpduino for some low buck ideas. We recently covered some other Hybrid Airships that are trying to scale things even further. And if you have your own blimpy ideas you’d like to pass along, please let us know via the Tip Line!

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