Schematic of a circuit

Hacking Flux Paths: The Surprising Magnetic Bypass

February 21, 2025 by 6 Comments

If you think shorting a transformer’s winding means big sparks and fried wires: think again. In this educational video, titled The Magnetic Bypass, [Sam Ben-Yaakov] flips this assumption. By cleverly tweaking a reluctance-based magnetic circuit, this hack channels flux in a way that breaks the usual rules. Using a simple free leg and a switched winding, the setup ensures that shorting the output doesn’t spike the current. For anyone who is obsessed with magnetic circuits or who just loves unexpected engineering quirks, this one is worth a closer look.

So, what’s going on under the hood? The trick lies in flux redistribution. In a typical transformer, shorting an auxiliary winding invites a surge of current. Here, most of the flux detours through a lower-reluctance path: the magnetic bypass. This reduces flux in the auxiliary leg, leaving voltage and current surprisingly low. [Sam]’s simulations in LTspice back it up: 10 V in yields a modest 6 mV out when shorted. It’s like telling flux where to go, but without complex electronics. It is a potential stepping stone for safer high-voltage applications, thanks to its inherent current-limiting nature.

The original video walks through the theory, circuit equivalences, and LTspice tests. Enjoy!

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Reviewing A Very Dodgy BSK-602 Adjustable Power Supply

February 21, 2025 by 16 Comments

There’s no shortage of cheap & cheerful power supplies which you can obtain from a range of online retailers, but with no listed certification worth anything on them calling them ‘dodgy’ is more of a compliment. On the [DiodeGoneWild] YouTube channel an adjustable power supply by the model name BSK-602 is tested and torn down to see exactly what less than $5 off sites like Alibaba will get you.

Perhaps unsurprisingly, voltage regulation is very unstable with massive drifting when left to heat up for a few hours, even though it does hit the 3 V to 24 V DC and 3 A output that it’s optimistically rated for. After popping open the adapter, a very basic switching mode power supply is revealed with an abysmal component selection and zero regard for safety or primary and secondary side isolation. With the case open, the thermal camera reveals that the secondary side heats up to well over 150 °C, explaining why the case was deforming and the sticker peeling off after a few hours of testing.

The circuit itself is based around a (possibly legit) UC3843RN 500 kHz current mode PWM controller, with the full schematic explained in the video. Highlights include the lack of inrush protection, no EMI filtering, a terrible & temperature-dependent voltage reference, not to mention poor component selection and implementation. Basically it’s an excellent SMPS if you want to blast EMI, fry connected electronics and conceivably burn down your home.

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Pocket Device Tracks Planets And The ISS

February 21, 2025 by 7 Comments

Ever been at a party and landed in a heated argument about exactly where the International Space Station (ISS) is passing over at that very instant? Me neither, but it’s probably happened to someone. Assuming you were in that situation, and lacked access to your smartphone or any other form of internet connected device, you might like the pocket-sized Screen Tracker from [mars91].

The concept is simple. It’s a keychain-sized item that combines an ESP32, a Neopixel LED, and a small LCD screen on a compact PCB with a couple of buttons. It’s programmed to communicate over the ESP32’s WiFi connection to query a small custom website running on AWS. That website processes orbit data for the ISS and the positions of the planets, so they can be displayed on the LCD screen above a map of the Earth. We’re not sure what font it uses, but it looks pretty cool—like something out of a 90s sci-fi movie.

It’s a great little curio, and these sort of projects can have great educational value to boot. Creating something like this will teach you about basic orbits, as well as how to work with screens and APIs and getting embedded devices online. It may sound trivial when you’ve done it before, but you can learn all kinds of skills pursuing builds like these.

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Hackaday Podcast Episode 309: Seeing WiFi, A World Without USB, Linux In NES In Animal Crossing

February 21, 2025 by 4 Comments

This week Hackaday Editors Elliot Williams and Tom Nardi start things off with updates on the rapidly approaching Hackaday Europe and the saga of everyone’s favorite 3D printed boat.

From there they’ll cover an impressive method of seeing the world via WiFi, Amazon’s latest changes to the Kindle ecosystem, and an alternate reality in which USB didn’t take over the peripheral world. You’ll also hear about a multi-level hack that brings the joys of Linux into the world of Animal Crossing, 3D printed circuit components, and the imminent release of KiCAD 9.

Stick around until the end to learn about a unique hardened glass from East Germany and the disappointing reality of modern voice control systems.

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Building A One Wheel With Tracks

February 21, 2025 by 6 Comments

One-wheels use motion-tracking hardware and fine motor control to let you balance on a single wheel. That’s neat and all, but [Michael Rechtin] had another idea in mind—what if a one-wheel used a track instead?

The idea behind the track was to make the one-wheel more capable on surfaces where wheels simply can’t compete. The tracked drivetrain was largely 3D printed, including some massive gears that are supplemented by a big old 150 mm ball bearing which sits around the drive motor itself. If you love planetary gear trains with a 4:1 reduction, this project is for you. Carbon-fiber reinforced filament was used for many of the parts to give them some additional strength. Control is a little different than a traditional one-wheel, since the flat-bottomed track means lean controls won’t work. Instead, a wireless hand throttle was constructed to enable the rider to command the direction of travel.

It’s not easy to ride, but the one-track does actually work. It’s capable of crawling its way around on grass and snow quite well. There were some issues with the printed tracks and rollers, particularly when turning, but tweaks to round out the track profile helped solve that issue to a degree. There’s a reason we often use wheels instead of tracks, but somehow tracks are still just cool.

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This Week In Security: OpenSSH, JumbledPath, And RANsacked

February 21, 2025 by 7 Comments

OpenSSH has a newly fixed pair of vulnerabilities, and while neither of them are lighting the Internet on fire, these are each fairly important.

The central observation made by the Qualsys Threat Research Unit (TRU) was that OpenSSH contains a code paradigm that could easily contain a logic bug. It’s similar to Apple’s infamous goto fail; SSL vulnerability. The setup is this: An integer, r, is initialized to a negative value, indicating a generic error code. Multiple functions are called, with r often, but not always, set to the return value of each function. On success, that may set r to 0 to indicate no error. And when one of those functions does fail, it often runs a goto: statement that short-circuits the rest of the checks. At the end of this string of checks would be a return r; statement, using the last value of r as the result of the whole function.

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A New 8-bit CPU For C

February 21, 2025 by 60 Comments

It is easy to port C compilers to architectures that look like old minicomputers or bigger CPUs. However, as the authors of the Small Device C Compiler (SDCC) found, pushing C into a typical 8-bit CPU is challenging. Lessons learned from SDCC inspired a new 8-bit architecture, F8. This isn’t just a theoretical architecture. You can find an example Verilog implementation in the SDDC project and on GitHub. The name choice may turn out to be unfortunate as there was an F8 CPU from Fairchild back in the 1970s that apparently few people remember.

In the video from FOSDEM 2025, [Phillip Krause] provides a nice overview of the how and why of F8. While it might seem odd to create a new 8-bit CPU when you can get bigger CPUs for pennies, you have to consider that 8-bit machines are more than enough for many jobs, and if you can squeeze one into an FPGA, it might be a good choice as opposed to having to get a bigger FPGA to hold your design and a 32-bit CPU.

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