Upgraded Plasma Thruster Is Smaller, More Powerful

When [Jay Bowles] demoed his first-generation ion thruster on Plasma Channel, the resulting video picked up millions of views and got hobbyists and professionals alike talking. While ionic lifters are nothing new, this robust multi-stage thruster looked (and sounded) more like a miniature jet engine than anything that had come before it. Optimizations would need to be made if there was even a chance to put the high-voltage powerplant to use, but [Jay] was clearly onto something.

Fast forward six months, and he’s back with his Mark II thruster. It operates under the same core principles as the earlier build, but swaps out the open-frame design and acrylic construction for a rigid 3D printed structure designed to more effectively channel incoming air. The end result is a thruster that’s smaller and has a lower mass, while at the same time boasting nearly double the exhaust velocity of its predecessor. Continue reading “Upgraded Plasma Thruster Is Smaller, More Powerful”

Cold War Military Telephones Now Usable Thanks To DIY Switch Build

The TA-1042 is the most badass looking telephone you’ll ever see. It’s a digital military telephone from the 1980s, but sadly non-functional unless it’s hooked up to the military phone switches it was designed to work with. These days, they’re really only useful as a heavy object to throw at somebody… that is, unless you had the suitable supporting hardware. As it turns out, [Nick] and [Rob] were able to whip up exactly that.

Their project involved implementing the TA-1042’s proprietary switching protocol on a Raspberry Pi Pico. The microcontroller’s unique Programmable I/O subsystem proved perfect for the task. With a little programming and a hat for the Pico to interface with the hardware, they were able to get the TA-1042 working as intended. It involved learning how to encode and decode the Manchester encoded data used by the Digital Non-secure Voice Terminal equipment. Notably, the TA-1042 isn’t the only phone you can use with this setup. You can also hook up other US military DNVT phones, like the TA-954 or TA-1035.

If you want this hardware for yourself, you can simply buy one of [Nick] and [Rob]’s DNVT switches from Tindie. Alternatively, you can roll your own with the source code provided on GitHub.

We’ve seen these phones before repurposed in an altogether different fashion. We’ve also taken a deep dive into the details of the military’s AUTOVON network.

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Jac Goudsmit and Ralf Porankiewicz at Supercon 2022

2022 Supercon: Jac And Ralf Explore The Secrets Of The Digital Compact Cassette

During the 1990s, music was almost invariably stored on CDs or cassette tapes. When the new millennium came around, physical formats became obsolete as music moved first to MP3 files, and later to network streams. But a few years before that big transition, there were several attempts at replacing the aging cassette and CD formats with something more modern. You might remember the likes of MiniDisc and Super Audio CD, but there were a few other contenders around.

The Digital Compact Cassette, or DCC, was one such format. Released by Philips in 1992 as a replacement for the analog audio cassette, it failed to gain traction in the market and disappeared before most people had even heard of it. Not so for [Jac Goudsmit] and [Ralf Porankiewicz] however, who have spent years researching all aspects of the DCC system and shared some of the results in their 2022 Supercon talk.

[Ralf] is the curator of the DCC Museum in Cathedral City, California, which owns examples of all DCC equipment ever released, as well as several devices that never made it to market. He also aims to document the history of audio recording and DCC’s contribution to it, which goes further than you might think. For example, the audio compression format used in the DCC system, called PASC, was an early version of what would later become MP3 – though most histories of audio compression ignore this fact.

[Jac], for his part, made an extensive study of all the technical features of the DCC format. He has written numerous articles about his findings, first in the DCC FAQ and later by maintaining the relevant Wikipedia articles. He is running several projects aimed at keeping the format alive, often in collaboration with the DCC Museum.

[Jac] and [Ralf] begin their talk with a brief introduction to the system and its media. DCC players were designed to be compatible with analog audio cassettes, so DCC cartridges are the same basic size, though with a different type of tape inside. Playback devices contain a complex set of magnetic heads to read either the analog signals from classic tapes, or the digital data stored on DCCs.

One unique feature of DCC is Interactive Text Transfer Service, or ITTS, which is a separate data area on the tape that can hold additional information like song lyrics or even simple animations. It was intended to be displayed on players that supported it, but no such devices were ever released. Luckily, [Jac] and [Ralf] managed to find a rare ITTS decoder system used in a tape mastering facility, and were able to reveal the contents of this “secret track”, which is present on all prerecorded tapes, for the first time.

User-recorded tapes never had any ITTS data, and differed from prerecorded ones in several other ways, too. The most obvious difference was that professionally-made tapes could be indexed by song title, while home-made ones could only jump to track numbers. [Jac] and [Ralf] are however working to enable all the professional features on home-made tapes as well, through a number of software and hardware projects.

The most basic software needed is an encoder and decoder for the PASC format, which [Jac] developed from existing MP1 sofware. But to explore some of the more obscure hardware features, he had to reverse-engineer several different DCC players. This led him to discover many interesting half-finished features: the ITTS data sector is one example, but he also found out that some players send ready-to-use VU meter data to their front panel, even though they are unable to display that information.

[Jac] was also one of the first people to buy the DCC-175 portable DCC player when it was released in 1995. This was the only DCC player ever sold with a computer interface, allowing direct transfer of digital audio between a computer and a DCC tape. The parallel port interface and its accompanying Windows 9x software are completely obsolete and unusable with modern PCs, so [Jac] is working on directly accessing the data from the DCC-175 through a custom cable. He’s making good progress: he already figured out the electrical interface and wrote some software that enables him to control the tape recorder directly.

We can’t help but be impressed by the amount of effort both [Jac] and [Ralf] have put into understanding and documenting all the intricacies of a long-obsolete audio format. Thanks to their efforts, we can still appreciate the impressive technology behind DCC – even if it never came close to replacing its analog cousin.

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Electric Skateboard Becomes Mobile Skate Park

While building a skate park might not appear to have much in common with software development, at they very least, they both suffer from a familiar problem: scalability. Bigger skate parks need more ramps and features, and there’s no real way to scale up a construction project like this efficiently like you could with certain kinds of software other than simply building more features. This was something [Kirk] noticed, but was able to scale up a skate park in a way we’ve never thought of before. He built a mobile skateboard ramp that can turn any place into a skate park.

The mobile and approximately sidewalk-width platform is able to move around thanks to an electric skateboard as its foundation. It adds a NVIDIA Jetson Nano for control with a PS4 controller for input, although steering a skateboard with an actuator took a few prototypes to figure out since skateboards are designed to be steered by shifting the rider’s weight. Since they are already designed to carry a human-amount of weight, though, it was at least able to tote the ramp around with relative ease. Another problem was lowering the ramp into position when it got to the desired area, but with an electrically-controlled jack and a few rounds of debugging was eventually able to do this without much issue.

With all of that project development behind him, [Kirk] can finally realize his dream of having ramps scattered all across his neighborhood like in the classic videogame Paperboy, without needing to build them all individually or ask for permission to place them around his neighbor’s homes. For any future iterations of this build, we might consider adding tank tracks to the electric skateboard for better off-road performance, like facilitating a jump across a patch of grass.

PCIe For Hackers: Extracting The Most

So, you now know the basics of approaching PCIe, and perhaps you have a PCIe-related goal in mind. Maybe you want to equip a single-board computer of yours with a bunch of cheap yet powerful PCIe WiFi cards for wardriving, perhaps add a second NVMe SSD to your laptop instead of that Ethernet controller you never use, or maybe, add a full-size GPU to your Raspberry Pi 4 through a nifty adapter. Whatever you want to do – let’s make sure there isn’t an area of PCIe that you aren’t familiar of.

Splitting A PCIe Port

You might have heard the term “bifurcation” if you’ve been around PCIe, especially in mining or PC tinkering communities. This is splitting a PCIe slot into multiple PCIe links, and as you can imagine, it’s quite tasty of a feature for hackers; you don’t need any extra hardware, really, all you need is to add a buffer for REFCLK. See, it’s still needed by every single extra port you get – but you can’t physically just pull the same clock diffpair to all the slots at once, since that will result in stubs and, consequently, signal reflections; a REFCLK buffer chip takes the clock from the host and produces a number of identical copies of the REFCLK signal that you then pull standalone. You might have seen x16 to four NVMe slot cards online – invariably, somewhere in the corner of the card, you can spot the REFCLK buffer chip. In a perfect scenario, this is all you need to get more PCIe out of your PCIe.

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Make Anything Clockwork With This Ridiculous Stick-On Device

Clockwork devices were popular right up until motors and electronics proved far more capable in just about every way. However, there’s something charming about a device you can wind up to make it do its thing. To recreate this feeling on modern technology, [Kousuke Saito] created a clockwork winder that you can fit to a wide variety of modern appliances. 

Somehow it just feels right.

The design is simple. It consists of a motor which is run from a battery. The two components are installed in a 3D printed housing with a magnet on the bottom. When the device is attached to a metal surface, a switch is activated which turns the motor on. The motor is attached to a large printed “winding key” that would be familiar to anyone who has used a clockwork toy or timepiece before. If the magnetic manner of activation is familiar, you might recall it from [Kousuke Saito’s] chirping cicada project.

It’s a silly build, to be sure. Regardless, when placed on certain appliances, like a simple fan, the motion really does imply that the clockwork winder is connected to the mechanism inside. It’s a falsehood, of course, but a joyous one.

We’ve featured some real clockwork hardware before, too, like these amazing time locks.

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Generating Instead Of Storing Meshes

The 64kB is a category in the demoscene where the total executable size must be less than 65,536 bytes, and at that size, storing vertexes, edges, and normal maps is a waste of space. [Ctrl-Alt-Test] is a French Demoscene group that has been doing incredible animations for the last 13 years. They’ve written an excellent guide on how they’ve been procedurally generating the meshes in their demos.

It all starts with cubes. By stacking them, overlaying them, reusing them, and tiling them you can get better compression than raw vertexes. Revolution was the next trick, as it uses just a few points, plotting it via Catmul-Rom splines, and revolving around an axis. The numbers are pairs of 32-bit floats and before compression, a detailed pawn on a chess board can weigh in at just 40 bytes. Just these few techniques can take you surprisingly far (as seen in the picture above).

They later worked on deforming cubes and placing them into a semi-randomized column, which happened to look a lot like plants. This isn’t the first generated vegetation we’ve seen, and the demoscene technique focused more on getting the shape and setting the mood rather than being accurate.

Signed distance fields are another useful trick that allows you to generate a mesh by implementing a signed distance function and then running a marching cubes algorithm on it. In a nutshell, a signed distance function just returns the distance to the closest point on a surface from a given point. This means you can describe shapes with just a single mathematical equation. As you can imagine, this is a popular technique in the demoscene world because it is so space efficient in terms of code and data. [Ctrl-Alt-Test] even has a deep dive into one of their projects, Immersion, with a breakdown of where the space is allocated.

There are plenty of other tips and tricks here, such as generating textures and developing a C++ hot reload system for faster iteration. It’s just incredible that the executable that plays the whole video is smaller than just a JPEG screenshot of the video. It’s a reminder that the demoscene is still fascinating with new tricks and experiences even as the hardware stays the same. Continue reading “Generating Instead Of Storing Meshes”