Building A Low-Cost Satellite Tracker

Looking up at the sky just after sunset or just before sunrise will reveal a fairly staggering amount of satellites orbiting overhead, from tiny cubesats to the International Space Station. Of course these satellites are always around, and even though you’ll need specific conditions to view them with the naked eye, with the right radio antenna and only a few dollars in electronics you can see exactly which ones are flying by at any time.

[Josh] aka [Ham Radio Crash Course] is demonstrating this build on his channel and showing every step needed to get something like this working. The first part is finding the correct LoRa module, which will be the bulk of the cost of this project. Unlike those used for most Meshtastic nodes, this one needs to be built for the 433 MHz band. The software running on this module is from TinyGS, which we have featured here before, and which allows a quick and easy setup to listen in to these types of satellites. This build goes much further into detail on building the antenna, though, and also covers some other ancillary tasks like mounting it somewhere outdoors.

With all of that out of the way, though, the setup is able to track hundreds of satellites on very little hardware, as well as display information about each of them. We’d always favor a build that lets us gather data like this directly over using something like a satellite tracking app, although those do have their place. And of course, with slightly more compute and a more directed antenna there is all kinds of other data beaming down that we can listen in on as well, although that’s not always the intent.

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How To Use That Slide Rule

You have that slide rule in the back of the closet. Maybe it was from your college days. Maybe it was your Dad’s. Honestly. Do you know how to use it? Really? All the scales? That’s what we thought. [Amen Zwa, Esq.] not only tells you how slide rules came about, but also how to use many of the common scales. You can also see his collection and notes on being a casual slide rule collector and even a few maintenance tips.

The idea behind these computing devices is devilishly simple. It is well known that you can reduce a multiplication operation to addition if you have a table of logarithms. You simply take the log of both operands and add them. Then you do a reverse lookup in the table to get the answer.

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Meet The Shape That Cannot Pass Through Itself

Can a shape pass through itself? That is to say, if one had two identical solids, would it be possible to orient one such that a hole could be cut through it, allowing the other to pass through without breaking the first into separate pieces? It turns out that the answer is yes, at least for certain shapes. Recently, two friends, [Sergey Yurkevich] and [Jakob Steininger], found the first shape proven not to have this property.

A 3D-printed representation of a cube passing through itself [image: Wikipedia]
Back in the late 1600s, Prince Rupert of the Rhine proved it was possible to accomplish this feat with two identical cubes. One can tilt a cube just so, and the other cube can fit through a tunnel bored through it. A representation is shown here.

Later, researchers showed this was also true of more complex shapes. This ability to pass unbroken through a copy of oneself became known as Rupert’s Property. Sometimes it’s an amazingly tight fit, but it seems to always work.

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ABCCAD Is Voxels Meets LEGO In AR

We get it, CAD software can be daunting to learn. Somehow [Boaztheostrich] found it so daunting he procrastinated his way into a AR voxel-based CAD app he calls “ABCCAD”, written in Godot for the Meta Quest 3.

The app is simplicity itself: pressing A or X on the controller spawns a cube, which you can place wherever you like in virtual space by moving the controller in real space. The trigger then saves the cube position. Grabbing a cube uses the controller’s grab buttons. You can even change colors (with B or Y), but like in OpenSCAD it appears that’s not actually going to have any effect on the exported STL. Check it out in action in the demo video embedded below.

As far as CAD applications go, this is as simplistic as it gets, but there’s a certain charm to its simplicity. It’s almost like virtual LEGO. Besides, TinkerCAD wasn’t much more complicated when it started out, and look at it now.

Sure, one could say if [Boaz] wanted to do CAD he’d have been better off putting the time into learning good old OpenSCAD or FreeCAD (which can now get you SolidWorks certs, apparently), but this is a fun little app that let him stretch his chops in Godot, another great open-source tool. ABCCAD is, itself, open-source under an MIT license.

We seem to have a paucity of posts under the Godot tag, so if you’ve got a hack that uses the open-source game engine, please send us a tip.

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Record-Breaking Robots At Guinness World Records

If you ever wanted to win a bar bet about a world record, you probably know about the Guinness book for World Records. Did you know, though, that there are some robots in that book? Guinness pointed some out in a recent post.

Ever wonder about the longest table-tennis rally with a robot or the fastest robotic cube solver? No need to wonder anymore.

Our favorite was the fastest robot to solve a puzzle cube. This robot solved the Rubik’s Cube in 103 milliseconds! Don’t blink or you’ll miss it in the video embedded. Of course, the real kudos go to the team that created the robot: [Matthew Patrohay], [Junpei Ota], [Aden Hurd], and [Alex Berta].

Another favorite was the smallest humanoid robot. In order to win this record, the robot must be able to move its shoulders, elbows, knees, and hips just like a human. It also has to be able to walk on two feet. This tiny little guy meets the requirements and stands only 57.6 mm (2.26 in) tall! Created by [Tatsuhiko Mitsuya] in April 2024, this robot can be controlled via Bluetooth.

We’ve seen entries in this category before — check them out in Almost Breaking The World Record For The Tiniest Humanoid Robot, But Not Quite.

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A clay mug is placed on a fire brick. Portions of the mug are glowing orange hot, and the heat is spreading across the surface. Some portions of the mug have cooled, and the heat has not reached other parts.

Thermite Pottery Fires Itself

Finely powdered aluminium can make almost anything more pyrotechnically interesting, from fireworks to machine shop cleanups – even ceramics, as [Degree of Freedom] discovered. He was experimenting with mixing aluminium powder with various other substances to see whether they could make a thermite-like combination, and found that he could shape a paste of aluminium powder and clay into a form, dry it, and ignite it. After burning, it left behind a hard ceramic material.

[Degree of Freedom] was naturally interested in the possibilities of self-firing clay, so he ran a series of experiments to optimize the composition, and found that a mixture of three parts of aluminium to five parts clay by volume worked best. However, he noticed that bubbles of hydrogen were forming under the surface of the clay, which could cause cracks during the firing. The aluminium was reacting with water to form the bubbles, somewhat like a unwanted form of aerated concrete, and for some reason the kaolinite in clay seemed to accelerate the reaction. Trying to passivate the aluminium by heating it in air or water didn’t prevent the reaction, but [Degree of Freedom] did find that clay extracted from the dirt in his back yard didn’t accelerate it as kaolinite did, and the mixture could dry out without forming bubbles.

This mixture wasn’t totally reliable, so to make it a bit more consistent [Degree of Freedom] added some iron oxide to accelerate the burn through an actual thermite reaction – some mixtures burned hot enough to start to melt the clay. After many tests, he found that sixteen parts clay, seven parts aluminium, and five parts iron oxide gave the best results. He fired two cups made of the mixture, a thin rod, and a cube, with mixed results. The clay expanded a bit during firing, which sometimes produced a rough finish, cracking, and fragility, but in some cases it was surprisingly strong.

The actual chemistry at work in the clay-aluminium mixtures is a bit obscure, but not all thermite reactions need to involve iron oxide, so there might have been some thermite component even in the earlier mixtures. If you need heat rather than ceramic, we’ve also seen a moldable thermite paste extruded from a 3D printer.

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Screenshot of the email received: Hi there, Upon a thorough review by our Risk Control Team, we are sorry to inform you that, your account access will be permanently disabled on December 13th, 2025 due to compliance policy requirements. Before this date, you may: 1) Complete any existing orders. 2) Pickup components from your parts inventory. 3) Withdraw your remaining account balance (JLC Balance) 4) Back up your historical Gerber Files or any other information. Please note that after December 13th, 2025, your account will be permanently locked and cannot be reopened. Best Regards, The JLCPCB Risk Control Team

JLCPCB Locking Accounts, Mentions “Risky IP Addresses, Activities”

In the past week, a few forum and Reddit threads have popped up, with people stating that JLCPCB has emailed them with a notice, saying their accounts are set up for terminations after an assessment by JLCPCB’s “Risk Control Team”. Reasons given are vague, the terminations are non-appealable, and if you’re planning a JLCPCB order sometime soon, it can certainly come as a surprise. From the looks of it, the accounts restricted do not appear to be tied to any specific country – and not even from the same “kind” of countries.

As quite a few people have observed, the JLCPCB reasoning resembles a compliance action way more than it resembles any sort of internal policy. A few days ago, JLCPCB has released a statement on their blog, claiming that a “history of risky IP addresses and risky activities” would be grounds for a termination, and mentioning “compliance” in ways that would hint at external legal pressures.

By now, quickly checking around Reddit and some other places, we’ve counted at least ten people affected so far – most of them have received emails about account closures, but at least one person has reported a denial when attempting to place an order, instead of getting an email ahead of time. The latter hints that there’s a number of people not yet notified about their account getting terminated, and the amount of people actually affected might very well be a fair bit larger than we can see.

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