When Electricity Doesn’t Take The Shortest Path

January 13, 2026 by 53 Comments

Everyone knows that the path of least resistance is the path that will always be taken, be it by water, electricity or the feet of humans. This is where the PCB presented by [ElectrArc240] on YouTube is rather confusing, as it demonstrates two similarly sized traces, one of which is much shorter than the other, yet the current opts to travel via the much longer trace. If you were to measure this PCB between each path, the shorter path has the lowest resistance at 0.44 Ω while the longer path is 1.44 Ω. Did the laws of physics break down here?

Of course, this is just a trick question, as the effective resistance for an electrical circuit isn’t just about ohmic resistance. Instead the relevant phrasing here is ‘path of least impedance‘, which is excellently demonstrated here using this PCB. Note that its return path sneaks on the back side along the same path as the long path on the front. To this is added a 1 MHz high current source that demonstrates the impact of alternating current, with reactance combining with the resistance.

Although for direct current it’s fair to say that impedance is the equivalent of resistance, once the inductance of a trace has to be taken into account – as in the case of AC and high-frequency signaling – the much higher inductance of the short path means that now the long path is actually the shortest.

When you are doing some impedance matching in your favorite EDA software while implementing an Ethernet RMII link or similar, this is basically part of the process, with higher frequencies requiring ever more stringent mechanisms to keep both sides happy. At some point any stray signals from nearby traces and components become a factor, never mind the properties of the PCB material.

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Playing A Game Of Linux On Your Sony Playstation 2

December 29, 2025 by 15 Comments

Until the 2000s, game consoles existed primarily to bring a bit of the gaming arcade experience to homes, providing graphical feats that the average home computer would struggle to emulate. By the 2000s this changed, along with the idea of running desktop applications on gaming console for some reason. Hence we got Linux for the PlayStation 2, targeting its MIPS R5900 CPU and custom GPU. Unlike these days where game consoles are reskinned gaming PCs, this required some real effort, as well as a veritable stack of accessories, as demonstrated by [Action Retro] in a recent video.

Linux on the PlayStation 2 was a bit of a rare beast, as it required not only the optional HDD and a compatible ‘fat’ PS2, but also an Ethernet adapter, VGA adapter and a dedicated 8 MB memory card along with a keyboard and mouse. PS2 Linux users were also not free to do what they wanted, with e.g. ripping PS2 game discs disallowed, but you could make your own games. All of which had to fit within the PS2’s meagre 32 MB of RAM.

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A photo of the SigCoreUC

SigCore UC: An Open-Source Universal I/O Controller For The Raspberry Pi

December 22, 2025 by 23 Comments

Recently, [Edward Schmitz] wrote in to let us know about his Hackaday.io project: SigCore UC: An Open-Source Universal I/O Controller With Relays, Analog I/O, and Modbus for the Raspberry Pi.

In the video embedded below, [Edward] runs us through some of the features which he explains are a complete industrial control and data collection system. Features include Ethernet, WiFi, and Modbus TCP connectivity, regulated 5 V bus, eight relays, eight digital inputs, four analog inputs, and four analog outputs. All packaged in rugged housing and ready for installation/deployment.

[Edward] says he wanted something which went beyond development boards and expansion modules that provided a complete and ready-to-deploy solution. If you’re interested in the hardware, firmware, or software, everything is available on the project’s GitHub page. Beyond the Hackaday.io article, the GitHub repo, the YouTube explainer video, there is even an entire website devoted to the project: sigcoreuc.com. Our hats off to [Edward], he really put a lot of polish on this project.

If you’re interested in using the Raspberry Pi for input/output you might also like to read about Raspberry Pi Pico Makes For Expeditious Input Device and Smart Power Strip Revived With Raspberry Pi.

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After Decades, Linux Finally Gains Stable GPIB Support

December 16, 2025 by 40 Comments

Recently, [Greg Kroah-Hartman] proclaimed the joyous news on the Linux Kernel Mailing List that stable General Purpose Interface Bus (GPIB) support has finally been merged into the 6.19 Linux kernel.

The GPIB is a short-range 8-bit, multi-master interface bus that was standardized as IEEE 488. It first saw use on HP laboratory equipment in the 1970s, but was soon after also used by microcomputers like the Commodore PET, Commodore 64 and others. Although not high-speed with just 8 MB/s, nor with galvanic isolation requirements, it’s an uncomplicated bus design that can be implemented without much of a blip on the BOM costs.

The IEEE 488 standard consists of multiple elements, with 488.1 defining the physical interface and 488.2 the electrical protocol. Over the decades a communication protocol was also developed, in the form of SCPI and its standardized way of communicating with a wide range of devices using a simple human-readable protocol.

Although the physical side of IEEE 488 has changed over the years, with Ethernet becoming a major alternative to the short GPIB cables and large connectors, the electrical protocol and SCPI alike are still very much relevant today. This latest addition to the Linux kernel should make it much easier to use both old and new equipment equipped with this bus.

Plug Into USB, Read Hostname And IP Address

December 15, 2025 by 16 Comments

Ever wanted to just plug something in and conveniently read the hostname and IP addresses of a headless board like a Raspberry Pi? Chances are, a free USB port is more accessible than digging up a monitor and keyboard, and that’s where [C4KEW4LK]’s rpi_usb_ip_display comes in. Plug it into a free USB port, and a few moments later, read the built-in display. Handy!

The device is an RP2350 board and a 1.47″ Waveshare LCD, with a simple 3D-printed enclosure. It displays hostname, WiFi interface, Ethernet interface, and whatever others it can identify. There isn’t even a button to push; just plug it in and let it run.

Here’s how it works: once plugged in, the board identifies itself as a USB keyboard and a USB serial port. Then it launches a terminal with Ctrl-Alt-T, and from there it types and runs commands to do the following:

  1. Find the serial port that the RP2350 board just created.
  2. Get the parsed outputs of hostname, ip -o -4 addr show dev wlan0, ip -o -4 addr show dev eth0, and ip -o -4 addr show to gather up data on active interfaces.
  3. Send that information out the serial port to the RP2350 board.
  4. Display the information on the LCD.
  5. Update periodically.

The only catch is that the host system must be able to respond to launching a new terminal with Ctrl-Alt-T, which typically means the host must have someone logged in.

It’s a pretty nifty little tool, and its operation might remind you, in concept, of how BadUSB attacks happen: a piece of hardware, once plugged into a host, identifies itself to the host as something other than what it appears to be. Then it proceeds to input and execute actions. But in this case, it’s not at all malicious, just convenient and awfully cute.

Tearing Down Walmart’s $12 Keychain Camera

December 15, 2025 by 47 Comments

Keychain cameras are rarely good. However, in the case of Walmart’s current offering, it might be worse than it’s supposed to be. [FoxTailWhipz] bought the Vivitar-branded device and set about investigating its claim that it could deliver high-resolution photos.

The Vivatar Retro Keychain Camera costs $12.88, and wears “FULL HD” and “14MP” branding on the packaging. It’s actually built by Sakar International, a company that manufactures products for other brands to license. Outside of the branding, though, [FoxTailWhipz] figured the resolution claims were likely misleading. Taking photos quickly showed this was the case, as whatever setting was used, the photos would always come out at 640 x 480, or roughly 0.3 megapixels. He thus decided a teardown would be the best way to determine what was going on inside. You can see it all in the video below.

Pulling the device apart was easy, revealing that the screen and battery are simply attached to the PCB with double-sided tape. With the board removed from the case, the sensor and lens module are visible, with the model number printed on the flex cable. The sensor datasheet tells you what you need to know. It’s a 2-megapixel sensor, capable of resolutions up to 1632 x 1212. The camera firmware itself seems to not even use the full resolution, since it only outputs images at 640 x 480.

It’s not that surprising that an ultra-cheap keychain camera doesn’t meet the outrageous specs on the box. At the same time, it’s sad to see major retailers selling products that can’t do what they say on the tin. We see this problem a lot, in everything from network cables to oscilloscopes.

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Mating Cycles: Engineering Connectors To Last

November 20, 2025 by 56 Comments

If you take a look around you, chances are pretty good that within a few seconds, your eyes will fall on some kind of electrical connector. In this day and age, it’s as likely as not to be a USB connector, given their ubiquity as the charger of choice for everything from phones to flashlights. But there are plenty of other connectors, from mains outlets in the wall to Ethernet connectors, and if you’re anything like us, you’ve got a bench full of DuPonts, banana plugs, BNCs, SMAs, and all the rest of the alphabet soup of connectors.

Given their propensity for failure and their general reputation as a necessary evil in electrical designs, it may seem controversial to say that all connectors are engineered to last. But it’s true; they’re engineered to last, but only for as long as necessary. Some are built for only a few cycles of mating, while others are built for the long haul. Either way, connectors are a great case study in engineering compromise, one that loops physics, chemistry, and materials science into the process.

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