The ‘Hidden’ Microphone Inside The Sipeed NanoKVM

December 20, 2025 by Maya Posch 11 Comments

Recently, [Jeff Geerling] dropped into the bad press feeding frenzy around Sipeed’s NanoKVM, most notably because of a ‘hidden’ microphone that should have no business on a remote KVM solution. The problem with that reporting is, as [Jeff] points out in the video below, that the NanoKVM – technically the NanoKVM-Cube – is merely a software solution that got put on an existing development board, the LicheeRV Nano, along with an HDMI-in board. The microphone exists on that board and didn’t get removed for the new project, and it is likely that much of the Linux image is also reused.

Of course, the security report that caused so much fuss was published back in February of 2025, and some of the issues pertaining to poor remote security have been addressed since then on the public GitHub repository. While these were valid concerns that should be addressed, the microphone should not be a concern, as it’d require someone to be logged into the device to even use it, at which point you probably have bigger problems.

Security considerations aside, having a microphone in place on a remote KVM solution could also be very useful, as dutifully pointed out in the comments by [bjoern.photography], who notes that being able to listen to beeps on boot could be very useful while troubleshooting a stricken system. We imagine the same is true for other system sounds, such as fan or cooling pump noises. Maybe all remote KVM solutions should have microphone arrays?

Of course, if you don’t like the NanoKVM, you could always roll your own.

Top image: the NanoKVM bundle from [Jeff]’s original review. (Credit: [Jeff Geerling])

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Testing 8 Solder Flux Pastes After Flux Killed A GeForce2 GTS

December 20, 2025 by Maya Posch 14 Comments

Riesba NC-559-ASM flux being applied. (Credit: Bits und Bolts, YouTube)

Flux is one of those things that you cannot really use too much of during soldering, as it is essential for cleaning the surface and keeping oxygen out, but as [Bits und Bolts] recently found, not all flux is made the same. After ordering the same fake Amtech flux from the same AliExpress store, he found that the latest batch didn’t work quite the same, resulting in a Geforce 2 GTS chip getting cooked while trying to reball the chip with uncooperative flux.

Although it’s easy to put this down to a ‘skill issue’, the subsequent test of eight different flux pastes ordered from both AliExpress and Amazon, including — presumably genuine — Mechanic flux pastes with reballing a section of a BGA chip, showed quite different flux characteristics, as you can see in the video below. Although all of these are fairly tacky flux pastes, with some, the solder balls snapped easily into place and gained a nice sheen afterwards, while others formed bridges and left a pockmarked surface that’s indicative of oxygen getting past the flux barrier.

Not all flux pastes are made the same, which also translates into how easy the flux remnants are to clean up. So-called ‘no clean’ flux pastes are popular, which take little more than some IPA to do the cleaning, rather than specialized PCB cleaners as with the used Mechanic flux. Although the results of these findings are up for debate, it can probably be said that ordering clearly faked brand flux paste is a terrible idea. While the top runner brand Riesba probably doesn’t ring any bells, it might be just a Chinese brand name that doesn’t have a Western presence.

As always, caveat emptor, and be sure to read those product datasheets. If your flux product doesn’t come with a datasheet, that would be your first major red flag. Why do we need flux? Find out.

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Reverse-Engineering The Intel 8087 Stack Circuitry

December 19, 2025 by Maya Posch 2 Comments

Although something that’s taken for granted these days, the ability to perform floating-point operations in hardware was, for the longest time, something reserved for people with big wallets. This began to change around the time that Intel released the 8087 FPU coprocessor in 1980, featuring hardware support for floating-point arithmetic at a blistering 50 KFLOPS. Notably, the 8087 uses a stack-based architecture, a major departure from existing FPUs. Recently [Ken Shirriff] took a literal closer look at this stack circuitry to see what it looks like and how it works.

Nearly half of the 8087’s die is taken up by the microcode frontend and bus controller, with a block containing constants like π alongside the FP calculation-processing datapath section taking up much of the rest. Nestled along the side are the eight registers and the stack controller. At 80 bits per FP number, the required registers and related were pretty sizeable for the era, especially when you consider that the roughly 60,000 transistors in the 8087 were paired alongside the 29,000 transistors in the 16-bit 8086.

Each of the 8087’s registers is selected by the decoded instructions via a lot of wiring that can still be fairly easily traced despite the FPU’s die being larger than the CPU it accompanied. As for the unique stack-based register approach, this turned out to be mostly a hindrance, and the reason why the x87 FP instructions in the x86 ISA are still quite maligned today. Yet with careful use, providing a big boost over traditional code, this made it a success by that benchmark, even if MMX, SSE, and others reverted to a stackless design.

Automatically Remove AI Features From Windows 11

December 18, 2025 by Maya Posch 63 Comments

It seems like a fair assessment to state that the many ‘AI’ features that Microsoft added to Windows 11 are at least somewhat controversial. Unsurprisingly, this has led many to wonder about disabling or outright removing these features, with [zoicware]’s ‘Remove Windows AI’ project on GitHub trying to automate this process as much as reasonably possible.

All you need to use it is your Windows 11-afflicted system running at least 25H2 and the PowerShell script. The script is naturally run with Administrator privileges as it has to do some manipulating of the Windows Registry and prevent Windows Update from undoing many of the changes. There is also a GUI for those who prefer to just flick a few switches in a UI instead of running console commands.

Among the things that can be disabled automatically are the disabling of Copilot, Recall, AI Actions, and other integrations in applications like Edge, Paint, etc. The reinstallation of removed packages is inhibited by a custom package. For the ‘features’ that cannot be disabled automatically, there is a list of where to toggle those to ‘off’.

Naturally, since Windows 11 is a moving target, it can be rough to keep a script like this up to date, but it seems to be a good start at least for anyone who finds themselves stuck on Windows 11 with no love for Microsoft’s ‘AI’ adventures. For the other features, there are also Winaero Tweaker and Open-Shell, with the latter in particular bringing back the much more usable Windows 2000-style start menu, free of ads and other nonsense.

Building And Testing A Turbine Driven Hydro Generator

December 18, 2025 by Maya Posch 24 Comments

The theory behind hydropower is very simple: water obeys gravity and imparts the gained kinetic energy onto a turbine, which subsequently drives a generator. The devil here is, of course, in all the details, as [FarmCraft101] on YouTube is in the process of finding out as he adds a small hydro plant to his farm dam. After previously doing all the digging and laying of pipe, in this installment, the goal is to build and test the turbine and generator section so that it can be installed.

The turbine section is 3D-printed and slides onto the metal shaft, which then protrudes from the back where it connects to a 230VAC, three-phase generator. This keeps it quite modular and easy to maintain, which, as it turns out, is a very good idea. After a lot of time spent on the lathe, cutting metal, and tapping threads, the assembled bulk of the system is finally installed for its first test run.

After all that work, the good news is that the 3D-printed turbine seems to work fine and holds up, producing a solid 440 RPM. This put it over the predicted 300 RPM, but that’s where the good news ends. Although the generator produces 28 watts, it’s officially rated for 3 kW at 300 RPM. Obviously, with the small size of this AliExpress-special, the expectation was closer to 750 watts, so that required a bit of investigation. As it turns out, at 300 RPM it only produces 9 watts, so obviously the generator was a dud despite cashing out $230 for it.

Hopefully, all it takes to fix this is to order a new generator to get this hydropower setup up and running. Fortunately, it seems that he’ll be getting his money back from the dud generator, so hopefully in the next video we’ll see the system cranking out something closer to a kilowatt of power.

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Bare Metal STM32: Increasing The System Clock And Running Dhrystone

December 18, 2025 by Maya Posch 9 Comments

When you start an STM32 MCU with its default configuration, its CPU will tick along at a leisurely number of cycles on the order of 8 to 16 MHz, using the high-speed internal (HSI) clock source as a safe default to bootstrap from. After this phase, we are free to go wild with the system clock, as well as the various clock sources that are available beyond the HSI.

Increasing the system clock doesn’t just affect the CPU either, but also affects the MCU’s internal buses via its prescalers and with it the peripherals like timers on that bus. Hence it’s essential to understand the clock fabric of the target MCU. This article will focus on the general case of increasing the system clock on an STM32F103 MCU from the default to the maximum rated clock speed using the relevant registers, taking into account aspects like Flash wait states and the APB and AHB prescalers.

Although the Dhrystone benchmark is rather old-fashioned now, it’ll be used to demonstrate the difference that a faster CPU makes, as well as how complex accurately benchmarking is. Plus it’s just interesting to get an idea of how a lowly Cortex-M3 based MCU compares to a once top-of-the line Intel Pentium 90 CPU.

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Building A Flying Blended Wing Body Aircraft Prototype

December 17, 2025 by Maya Posch 16 Comments

Anyone with an inkling of interest in super-sized remote control aircraft probably has at least seen some of the mind-blowing projects that [Ramy RC] has worked on over the years, with examples like the ongoing Airbus A380-800 build approaching the size of a full-sized business jet. That said, they recently got the offer to build a flying prototype of the Natilus Horizon, a blended wing body (BWB) aircraft that’s currently being developed into a full-sized production aircraft.

Suffice it to say that BWB RC aircraft isn’t something that they have built before, but as co-founder of Natilus, [Aleksey Matyushev], explains, they want to prove in this manner that building scale prototypes of future production aircraft is not nearly as complex as it’s often made out to be. Meaning that even two blokes in a shed as is the case here should be able to pull it off.

Natilus was founded in 2016 amidst strongly rising interest in these BWB aircraft designs that may one day threaten today’s tubes-with-wings. Their Kona design would be the cargo version and this Horizon prototype that [Ramy RC] is building the passenger version.

In this first video of two total, we can see the CAD project of the prototype and how the basic aircraft structure is being constructed out of carbon fiber composite, wood and foam. To this the engine nacelles, landing gear and wings are mounted, readying it for its maiden flight. The Natilus engineers have previously done all the simulations that should mean that it’ll fly like a glider, but we will have to wait until the next video to see whether that is the case.

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