Flying Submarine Documentary Is A Story Of Defied Assumptions

June 25, 2023 by Donald Papp 39 Comments

Donald Reid had a passion for applying himself to challenging problems, and in many ways his life’s work was that of developing a prototype submersible aircraft — or flying submarine — for which his son Bruce was a test pilot. [Jesse Moody] brought to our attention a fantastic documentary he created (with a short teaser trailer here) in which he interviews Bruce, and in the process teaches us all about a story that spanned decades and formed an important part of aviation history. Bruce experienced his share of hair-raising moments while testing the craft, but still has all of his fingers and limbs. Still, in his own words, “you wouldn’t be doing that kind of testing today!”

In many ways, the story revolves around defying assumptions. Without context, a “flying submarine” project might sound like a lone kook’s obsession, but Donald Reid was nothing of the sort. He was a brilliant engineer who was able solve problems by applying his skill and intellect with a laser-like focus. And it turns out that getting a submerged vehicle to successfully transition from waterbound craft to airborne is a source of numerous and novel problems that were not trivial to solve. In fact, these problems needed to be solved in order to develop the Tomahawk cruise missile, which is launched by submarine. And that brings us to the lawsuit that bookended it all.

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A 32-Bit RISC-V CPU Core In 600 Lines Of C

June 24, 2023 by Donald Papp 29 Comments

If you have ever wanted to implement a RISC-V CPU core in about 600 lines of C, you’re in luck! [mnurzia]’s rv project does exactly that, providing a simple two-function API.

Technically, it’s a user-level RV32IMC implementation in ANSI C. There are many different possible flavors of RISC-V, and in this case is a 32-bit base integer instruction set (RV32I), with multiplication and division extension (M), and compressed instruction set extension (C).

There’s a full instruction list and examples of use on the GitHub repository. As for readers wondering what something like RISC-V emulation might be good for, it happens to be the not-so-secret sauce to running Linux on an RP2040.

Robodog Goes Free Thanks To Unofficial SDK

June 24, 2023 by Donald Papp 8 Comments

What’s better than a pretty nice legged robot? One with an alternate SDK version that opens up expensive features, of course. The author didn’t like that the original SDK only came as pre-compiled binaries restricted to the most expensive models, so rolled up their sleeves and started writing a new one.

The manufacturer’s SDK limits access to programmatic functions, but that needn’t stop *you*.

There are a number of commercially-available robotic quadrupeds that can trace their heritage back to the MIT Mini Cheetah design, and one of them is the Unitree Go1 series which sports a distinctive X-shaped sensor cluster on its “face”. The basic models are affordable (as far as robots go, anyway) but Unitree claims only the high-priced EDU model can be controlled via the SDK. Happily, the Free Dog SDK provides a way to do exactly that.

The SDK is a work in progress, but fully usable and allows the user to send various high level and low level commands to the Go1 robots. High level examples include things like telling the robot to perform pushups, turn 90 degrees, or walk. Low level commands are things like specifying exact positions or torque levels for individual limbs. With the new SDK, doing those things programmatically is only a Python script away.

Know any other robots that might be based on the same system? This SDK might work on them, too.

3D Printering: Treating Filament Like Paint Opens Wild Possibilities

June 17, 2023 by Donald Papp 27 Comments

New angles and concepts in 3D printing are always welcome, and we haven’t seen anything quite like [Horn & Rhode]’s 3D prints that do not look anything like 3D prints, accomplished with an experimental tool called HueForge. The concept behind it is simple (though not easy), and the results can be striking when applied correctly.

3D prints that *really* don’t look 3D-printed.

The idea is this: colored, melted filament is, in a sense, not that different from colored paint. Both come in various colors, are applied in thin layers, and blend into new colors when they do so. When applied correctly, striking imagery can emerge. An example is shown here, but there are several more both on the HueForge project page as well as models on Printables.

Instead of the 3D printer producing a 3D object, the printer creates a (mostly) flat image similar in structure to a lithophane. But unlike a lithophane, these blend colors in clever and effective ways by printing extremely thin layers in highly precise ways.

Doing this effectively requires a software tool to plan the color changes and predict how the outcome will look. It all relies on the fact that even solid-color filaments are not actually completely opaque — not when printed at a layer height of 0.08 mm, anyway — and colors will, as a result, blend into one another when layered. That’s how a model like the one shown here can get away with only a few filament changes.

Of course, this process is far from being completely automated. Good results require a solid amount of manual effort, and the transmissivity of one’s particular filament choices plays a tremendous role in how colors will actually blend. That’s where the FilaScope comes in: a tool to more or less objectively measure how well (or how poorly) a given filament transmits light. The results plug into the HueForge software to better simulate results and plan filament changes.

Print result, showing results of filament blending.

Tilted to catch the light, giving an idea of how the print is structured.

When done well, it’s possible to create things that look nothing at all like what we have come to expect 3D-printed things to look. The cameo proof-of-concept model is available here if you’d like to try it for yourself, and there’s also an Aztec-style carving that gives a convincing illusion of depth.

[Horn & Rhode] point out that this concept is still searching for a right-sounding name. Front-lit lithophane? Reverse lithophane? Filament painting? Color-blended bas-relief? If you have a better idea, we urge you not to keep it to yourself because [Horn & Rhode] absolutely want to hear from you.

IKEA LACK Table Becomes Extremely Affordable DIY Copy Stand

June 16, 2023 by Donald Papp 14 Comments

A copy stand is a tool used to capture images of photos, artwork, books, and things of a similar nature. It holds a camera perpendicular to a large and flat surface, upon which the subject rests.

A threaded rod provides effective vertical adjustment.

They are handy, but there’s no need to spend a lot when [BlandPasta]’s DIY copy stand based on a cheap IKEA LACK table can be turned into an economical afternoon project with the help of simple hardware and a few 3D printed parts.

The main structure comes from a mixture of parts from two LACK tables: one small and one normal-sized. A tabletop is used as the bed, and the square legs make up the structural parts with the help of some printed pieces. A threaded rod combined with some captive hardware provides a way to adjust the camera up and down with a crank, while one can manually slide the horizontal camera mount as needed to frame the subject appropriately.

This is a clever remix of IKEA parts, and the somewhat matte white finish of the LACK complements photography well. Adding some DIY LED lighting is about all it takes to get a perfectly serviceable copy stand that won’t break the bank.

These Illusions Celebrate Exploiting Human Senses

June 16, 2023 by Donald Papp 7 Comments

Illusions are perceptual experiences that do not match physical reality, and the 2023 Illusion of the Year contest produced a variety of nifty ones that are worth checking out. A video for each is embedded below the break, but we’ll briefly explain each as well.

Some of the visual illusions play with perspective. One such example happens to be the contest winner: Platform 9 3/4 has a LEGO car appear to drive directly through a wall. It happens so quickly it’s difficult to say what happened at all!

Another good one is the Tower of Cubes, which appears as two stacks of normal-looking hollow cubes, but some of the cubes are in fact truly bizarre shapes when seen from the side. This is a bit reminiscent of the ambiguous cylinder illusion by Japanese mathematician and artist [Kokichi Sugihara].

Cornelia is representative of the hollow face illusion, in which a concave face is perceived as a normal convex one. (Interestingly this illusion is used to help diagnose schizophrenia, as sufferers overwhelmingly fail to perceive the illusion.)

The Accelerando Illusion is similar to (but differs from) an auditory effect known as the Risset Rhythm by composer Jean-Claude Risset. It exploits ambiguities in sound to create a dense musical arrangement that sounds as though it is constantly increasing in tempo.

The Buddha’s Ear Illusion creates the illusion of feeling as though one’s earlobe is being stretched out to an absurd length, and brings to mind the broader concept of body transfer illusion.

While it didn’t appear into the contest, we just can’t resist bringing up the Thermal Grill Illusion, in which one perceives a painful burning sensation from touching a set of alternating hot and cold elements. Even though the temperatures of the individual elements are actually quite mild, the temperature differential plays strange tricks on perception.

A video of each of the contest’s entries is embedded below, and they all explain exactly what’s going on for each one, so take a few minutes and give them a watch. Do you have a favorite illusion of your own? Share it in the comments!

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Ferrofluid Drum Synth Dances To The Beat

June 15, 2023 by Donald Papp 17 Comments

[Love Hultén]’s work often incorporates reactive sound elements, and his Ferrofluid drum synth is no exception. Sadly there are no real build details but have no fear: we’ve gathered plenty of DIY insights when it comes to ferrofluid-based projects.

Ferrofluid isn’t easy to work with, but there are plenty of DIY resources to make things easier.

First of all, ferrofluid is shockingly expensive stuff. But if you can get your hands on some old VHS tapes and acetone, you can make your own. Second, working with ferrofluid to make reactive elements is harder than it may look. Particularly, making the stuff dance to sound beats isn’t as simple as putting a container of the stuff in front of a speaker coil, but people have discovered a few ways that work more reliably than others.

[Love Hultén]’s drum synth was inspired by this custom Bluetooth speaker with dancing ferrofluid by [Dakd Jung], which drives an electromagnetic coil with frequencies selected from the audio with an MSGEQ7 equalizer. That way, only frequencies that work best for moving the fluid in interesting ways get used for the visualization. The MSGEQ7 spectrum analyzer chip is very useful for music-driven projects, as demonstrated by these sound-reactive LED shades which illustrate the audio element nicely.

The coils that create the electromagnetic field causing ferrofluid to move can take different forms, but two very interesting ones are this 12-layer PCB coil and for more intricate displays, there’s a 12×21 coil array that creates a dot-matrix-like display.

We have one last tip to share about enclosures. Some readers may have noticed that this drum synth project is housed in what looks like a piece of painted lumber. Wood is certainly a versatile material for making custom shapes, and for lettering and labels it turns out that toner transfer works just as well on wood as it does for making custom PCBs.

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