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Hackaday Links: February 12, 2023

So, maybe right now isn’t the best time to get into the high-altitude ballooning hobby? At least in the US, which with the downing of another — whatever? — over Alaska, seems to have taken a “Sidewinders first, threat identification later” approach to anything that floats by. The latest incident involved an aircraft of unknown type, described as “the size of a small car” — there’s that units problem again — that was operating over Prudhoe Bay off the northern coast of Alaska. The reason that was given for this one earning a Sidewinder was that it was operating much lower than the balloon from last week, only about 40,000 feet, which is well within the ceiling of commercial aviation. It was also over sea ice at the time of the shootdown, making the chance of bothering anyone besides a polar bear unlikely. We’re not taking any political position on this whole thing, but there certainly are engineering and technical aspects of these shootdowns that are pretty interesting, as well as the aforementioned potential for liability if your HAB goes astray. Nobody ever really benefits from having an international incident on their resume, after all.

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This Infinity Dodecahedron Build Shows All The Tricks

The infinity dodecahedron is one of those super eye-catching builds that many of us hardware hackers have on our ‘build one day’ project list. The very thought of actually doing it strikes a little fear into the heart of even the most intrepid maker, once you start to think about all the intricate little details and associated ways it could all go horribly wrong. Luckily for us, [Hari Wiguna] has documented his latest build as a long video build log, showing lots of neat tricks and highlighting many problems along the way. With the eventual goal of removing many of the issues that make such a build tricky, [Hari] hopes to make it practically easy. Let’s see how that turns out!

HASL-finished castellated (half hole) edge contacts make butt-jointing a breeze

A common route for such a build relies on appropriately shaped 3D printed frame parts, with some kind of clear plastic for the 12 faces, and LED strips stuck to the inside of each of the 30 edges. Whilst this works, [Hari] thought he could do a bit better, using butt-jointed PCBs as the frame material.

The PCBs handily double up as something to solder LEDs onto (because that’s what PCBs are mostly intended for!) as well as a way to pass power and data signals around the frame in a minimally visible way. As will become obvious from the lengthy discussion in the video, a few simple tricks here and there are needed to make this strategy work. With the recent proliferation of PCB modules using castellated edges for termination, the usual Chinese PCB fab services have all started offering very good value services for this feature. Once a PCB feature that was a specialized (read that as ‘expensive’) offering, it is now quite affordable on your average maker’s budget.

Data path planning? Just use paper and tape!

One immediate practical issue was how to pass the data connection around from edge to edge, given that there are three edges per vertex. The solution [Hari] came up with was simple, just duplicate the signals on each end of the PCB, so the data out signal can be tapped from either end, as required.

Even with 3D printed jigs to hold the PCBs at just the right angles, there’s still some wiggle and a little risk of edges not quite aligning, due to accumulated errors around the frame. It did come together in the end, with the expected spectacular visuals. We’re sure many of you will be waiting for [Hari] to release the next version of the design to the community, hopefully with even more of the ease-of-build issues resolved, because we want one even more now.

Naturally, this is by no means the first infinity platonic solid we’ve seen, here’s a smaller one for starters. If you remove the mirrors and LEDs, then you’re just left with a plain old dodecahedron, like this cool folding project.

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Dazzling Desktop Dodecahedron

Much like us, [AGBarber] digs all the infinity polyhedra already out there, but laments the fact that almost all of them are too large to be used as desktop distractions conversation pieces. That’s probably because it’s a lot easier to build ’em big, but that didn’t stop [AGBarber] from trying, succeeding spectacularly, and paving the way for anyone who wants to take on the challenge of building a dazzling desk toy of their own.

We all know that all those little strips of LEDs have to be chained together somehow. Wires would work fine in a larger version, but at roughly softball size, they become a tedious and fiddly nightmare. So what did [AGBarber] do instead? That’s right, they designed two different types of custom corner PCBs. The 3D printed brackets that hold the LEDs and the panels together are no cakewalk, either — [AGBarber] recommends using a resin printer if you have access to one, though it isn’t strictly required.

Everything about this project is open source, including a bonus printable jig for gluing the brackets together at just the right angles. All the steps are well-documented, from applying the mirror film to programming the Wemos D1 mini that controls the lights [AGBarber] programmed in a ton of animations, too, which you can watch after the break.

Want to build a small infinity thingy that isn’t quite so difficult? Crack open a cold one and check out these cool coasters.

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Infinity Icosahedron Is Difficult To Contemplate Even Looking Right At It

Cubes and pyramids are wonderful primitive three-dimensional objects, but everyone knows that the real mystical power is in icosahedrons. Yes, the twenty-sided polyhedron does more than just ruin your saving throws in tabletop RPGs – it can also glow and look shiny in your loungeroom at home.

[janth]’s build relies on semitransparent acrylic mirrors for the infinity effect, lasercut into triangles to form the faces of the icosahedron. The frame is built out of 3D printed rails which slot on to the acrylic mirrors, and also hold the LED strips. [janth] chose high-density strips with 144 LEDs per meter for a more consistent effect, and added frosted acrylic diffusers to all the strips for a clean look with less hotspots from the individual LEDs.

An ESP32 runs the show, and the whole assembly is epoxied together for strength. The final effect is very future disco, and it’s probably against medical advice to stare at it for more than 5 minutes at a time.

The infinity effect is a popular one, and we’ve seen a beautiful cube build by [Heliox] in recent times. Of course, if you do manage to build an actual portal through time and space, and not just a lamp that looks like one, be sure to send us a tip. Video after the break.

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Infinity Cube Is Gorgeous Yet Simple

Typically when we hear the words “LED” and “Cube”, we think of small blinking devices on protoboard designed to flex one’s programming and soldering skills. However, while [Heliox]’s Cube Infini could be described as “a cube of LEDs”, it’s rather a different beast (video in French, subtitles available).

The cube starts with a 3D printed frame, designed in Fusion 360. The devil really is in the details — [Heliox] puts in nice touches, such as the artistic cube relief on the base, and the smart integrated cable management in the edges. The faces of the cube are plexiglass sheets, covered with a one-way reflective film that is applied in a similar manner to automotive window tint. For lighting, a high-density LED strip is fitted to the inside edges, chosen for maximum visual effect. It’s controlled by an IR remote and a cheap control module from Amazon.

While the build contains no particularly advanced tools, materials, or techniques, the final result is absolutely stunning. It’s a piece we’d love to have as a lamp in a stylish loungeroom or study. [Heliox] does a great job of explaining how the cube is designed and fits together, and it’s a testament to just what can be achieved with a little ingenuity and hard work.

Once you’re done here, check out this ping-pong based build.

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A Table From Beyond Infinity

Infinity mirrors are some far-out table mods and make a great centerpiece. Instructables user [bongoboy23] took a couple steps beyond infinity when designing this incredible table tailor-made for our modern age.

Poplar and pine wood make up the framing, and red oak — stained and engraved — make for a chic exterior. Programmed with Arduino and run on a Teensy 3.1, the tabletop has 960 LEDs in forty sections. There are, four USB ports hidden behind sliding panels, as well as a two-port AC outlet and an inductive charging pad and circuit.  A hidden Adafruit TFT touchscreen display allows the user to control the table’s functions. Control is limited to changing lighting functions, but Pac-Man, Snake, and text features are still to come!

Weighing in at $850, it’s not a cheap build, but it looks amazing.

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Cityscape Infinity Table

Redditor [ squishy0eye] lacked a coffee table and wanted an infinity mirror. So, in a keen combination of the two, she built an infinity mirror table the resembles a nighttime cityscape.

Skimming over many of table’s build details, [squishy0eye] paused to inform the reader that an MDF base was used underneath the mirrors, with a hole drilled for the future power cable. For the top pane, she overlaid privacy screen mirror film onto tempered glass, turning it into a one-way mirror. The bottom pane is acrylic plastic due to the need to drill holes to hide the cables for each ‘building’ — the same mirror film was applied here as well. Wood was cut into rectangles for the building shapes and super glued around the holes and in the corresponding spots underneath to prevent any bowing in the acrylic. A small gap was left in each ‘building’ to run the 5050 non-waterproof LED strips around and back into the hole for power.

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