The Importance Of Current Balancing With Multi-Wire Power Inputs

February 24, 2025 by Maya Posch 87 Comments

In an ideal world, devoid of pesky details like contact resistance and manufacturing imperfections, you would be able to double the current that can be provided to a device by doubling the number of conductors without altering the device’s circuitry, as each conductor would carry the exact same amount of current as its neighbors. Since we do not actually live inside a simplified physics question’s scenario, multi-wire powering of devices comes with a range of headaches, succinctly summarized in the well-known rule that electricity always seeks the path of least resistance.

As recently shown by NVidia with their newly released RTX 50-series graphics cards, failure to provide current balancing between said different conductors will quickly turn it into a practical physics demonstration of this rule. Initially pinned down as an issue with the new-ish 12VHPWR connector that was supposed to replace the 6-pin and 8-pin PCIe power connectors, it turns out that a lack of current balancing is plaguing NVidia GPUs, with predictably melty results when combined with low safety margins.

So what exactly changed that caused what seems to be a new problem, and why do you want multi-wire, multi-phase current balancing in your life when pumping hundreds of watts through copper wiring inside your PC?

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Does The 12VHPWR Connector Really Wear Out After 30 Mating Cycles?

February 23, 2025 by Maya Posch 50 Comments

When PCI-SIG introduced the 12VHPWR power connector as a replacement for the 6- and 8-pin PCIe power connectors, it created a wave of controversy. There were enough cases of melting GPUs, PSUs, and cables to set people on edge. Amidst this controversy, [JayzTwoCents] decided to do some scientific experimentation, Mythbusters-style, specifically: do these 12VHPWR (or the 12V-2×6 successor) wear out upon hitting the often cited 30 mating cycles? If this is the case, it could explain why people see wildly different current loads between the wires in their GPU power cables. Perhaps reviewers and hardware enthusiasts should replace their GPU power cables more often.

Like many Mythbuster experiments, the outcome is less than clear, as can be observed in the below graph from one data set. Even after 100 mating cycles, there was no observable change to the contact resistance. One caveat: this was only performed on the GPU side of the connector. The first cable tested was a newer connector type that uses a single-split leaf spring design. Initially, most of the 12VHPWR connectors had a double- or triple-dimple design to contact the pin, so [Jayz] tested one of these, too.

The amazing thing with the 2022-era cable that got pulled new out of packaging and tested was that it looked terrible under the microscope in terms of tolerances and provided a very uneven load, but it got better over time and also lasted 100 cycles. However, it must be said that ‘lasted’ is a big word here, as the retention tab wore off by this point, and the connector was ready to fall out with a light breeze.

Perhaps the ‘mating cycles’ specification is more about the connector as a whole, as well as how the connector is (ab)used, at which point good (long-term) contact is no longer assured. Along with the different types of Molex Mini- and Micro-Fit style connectors, it’s worth keeping an eye on with more applications than just GPUs.

We have certainly seen some burned connectors. Particularly in 3D printers.

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How Rutherford Proved That Atoms Are Mostly Empty Space

February 23, 2025 by Maya Posch 26 Comments

By the beginning of the 20th century scientists were only just beginning to probe the mysteries of the atomic world, with the exact nature of these atoms subject to a lot of speculation and theory. Recently [The Action Lab] on YouTube replicated one of the most famous experiments performed at the time, commonly known as Rutherford’s gold-foil experiment.

A part of Rutherford’s scattering experiments, this particular experiment involved shooting alpha particles at a piece of gold foil with the source, foil, and detector placed in a vacuum vessel. Rutherford’s theoretical model of the atom that he developed over the course of these experiments differed from the contemporary Thomson model in that Rutherford’s model postulated that atoms consisted of a single large charged nucleus at the core of the atom, with the electrons spread around it.

As can be seen in the video, the relatively large alpha particles from the Americium-241 source, available from many smoke detectors, will most of the time zip right through the foil, while suffering a pretty major deflection in other times when a nucleus is hit. This is consistent with Rutherford’s model of a small nucleus surrounded by what is effectively mostly just empty space.

While Rutherford used a screen that would light up when hit with alpha particles, this experiment with a Geiger counter is an easy way to replicate the experiment, assuming that you have access to a large enough vacuum chamber.

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Reviewing A Very Dodgy BSK-602 Adjustable Power Supply

February 21, 2025 by Maya Posch 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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Microsoft (Again) Claims Topological Quantum Computing With Majorana Zero Mode Anyons

February 20, 2025 by Maya Posch 5 Comments

As the fundamental flaw of today’s quantum computers, improving qubit stability remains the focus of much research in this field. One such stability attempt involves so-called topological quantum computing with the use of anyons, which are two-dimensional quasiparticles. Such an approach has been claimed by Microsoft in a recent paper in Nature. This comes a few years after an earlier claim by Microsoft for much the same feat, which was found to be based on faulty science and hence retracted.

The claimed creation of anyons here involves Majorana fermions, which differ from the much more typical Dirac fermions. These Majorana fermions are bound with other such fermions as a Majorana zero mode (MZM), forming anyons that are intertwined (braided) to form what are in effect logic gates. In the Nature paper the Microsoft researchers demonstrate a superconducting indium-arsenide (InAs) nanowire-based device featuring a read-out circuit (quantum dot interferometer) with the capacitance of one of the quantum dots said to vary in a way that suggests that the nanowire device-under-test demonstrates the presence of MZMs at either end of the wire.

Microsoft has a dedicated website to their quantum computing efforts, though it remains essential to stress that this is not a confirmation until their research is replicated by independent researchers. If confirmed, MZMs could provide a way to create more reliable quantum computing circuitry that does not have to lean so heavily on error correction to get any usable output. Other, competing efforts here include such things as hybrid mechanical qubits and antimony-based qubits that should be more stable owing to their eight spin configurations.

The US Military’s Unsecured UFO Satellites And Their Use By Russia

February 19, 2025 by Maya Posch 31 Comments

Something that you generally don’t expect as a North-America-based enthusiast, is to listen in on Russian military communications during their war in Ukraine via WebSDR, or that these communications would be passing through US military satellites that are happy to just broadcast anything. Yet that’s the situation that the Saveitforparts YouTube channel recently described. As it turns out, there is a gaggle of UFOs up there, as the US DoD lovingly calls them.

Between 1979 and 1989 eight FLTSATCOM launches took place, with FLTSATCOM 7 and 8 still operating today. They were later joined by their successor UHF Follow-On (UFO) with 11 launches between 1993 and 2003. All of these operate in the UHF spectrum, with some UFO satellites also covering other bands. Their goal is to provide communication for the military’s forces, with these satellites for the most part acting as simple repeaters. Over time non-military parties learned to use these satellites too, even if it’s technically illegal in many jurisdictions.

As described in the video, if you listen in on WebSDR streams from Ukraine, you can not only find encrypted military comms, but also unencrypted Russian radio traffic. It seems that in lieu of being provided with proper (encrypted) radio systems, Russian forces are using these US military satellites for communication much like how US (and NATO) forces would have. This is reminiscent of how Russian troops were caught using Discord via Starlink for communication, before Russian command shutdown Discord.

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Series Hybrid Semi-Trucks: It Works For Locomotives So Why Not?

February 18, 2025 by Maya Posch 67 Comments

The current Edison Motors semi-truck prototype. (Credit: Edison Motors)

Canadian start-up Edison Motors may not seem like much at first glance — consisting of fewer than two dozen people in a large tent — but their idea of bringing series hybrid technology to semi-trucks may just have wheels. The concept and Edison Motors’ progress is explained in a recent video by The Drive on Youtube, starting off with the point that diesel-electric technology is an obvious fit for large trucks like this. After all, it works for trains.

In a series hybrid, there are two motors: a diesel generator and an electric motor (diesel-electric). This was first used in ships in the 1900s and would see increasing use in railway locomotives starting in the early 20th century. In the case of Edison Motors’ current prototype design there is a 9.0 liter Scania diesel engine which is used solely as a generator at a fixed RPM. This is a smaller engine than the ~15 liter engine in a conventional configuration and also doesn’t need a gearbox.

Compared to a battery-electric semi-truck, like the Tesla Semi, it weighs far less. And unlike a hydrogen-fuel cell semi-truck it actually exists and doesn’t require new technologies to be invented. Instead a relatively small battery is kept charged by the diesel generator and power fed back into the battery from regenerative braking. This increases efficiency in many ways, especially in start-stop traffic, while not suffering a weight penalty from a heavy battery pack and being able to use existing service stations, and jerry cans of diesel.

In addition to full semi-trucks Edison Motors also works on conversion kits for existing semi-trucks, pick-up trucks and more. Considering how much of the North American rolling stock on its rail systems is diesel-electric, it’s more amazing that it would have taken so long for the same shift to series hybrid on its road. Even locomotives occasionally used direct-drive diesel, but the benefits of diesel-electric hybrids quickly made that approach obsolete.

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