Repair And Reverse-Engineering Of Nespresso Vertuo Next Coffee Machines

January 21, 2026 by Maya Posch 34 Comments

Well there’s your problem. (Credit: Mark Funeaux, YouTube)

Akin to the razor-and-blades model, capsule-based coffee machines are an endless grind of overpriced pods and cheaply made machines that you’re supposed to throw out and buy a new one of, just so that you don’t waste all the proprietary pods you still have at home. What this also means is a seemingly endless supply of free broken capsule coffee makers that might be repairable. This is roughly how [Mark Furneaux] got into the habit of obtaining various Nespresso VertuoLine machines for attempted repairs.

The VirtuoLine machines feature the capsule with a bar code printed on the bottom of the lip, requiring the capsule to be spun around so that it can be read by the optical reader. Upon successful reading, the code is passed to the MCU after which the brewing process is either commenced or cruelly halted if the code fails. Two of the Vertuo Next machines that [Mark] got had such capsule reading errors, leading to a full teardown of the first after the scanner board turned out to work fine.

Long story short and many hours of scrubbed footage later, one machine was apparently missing the lens assembly on top of the photo diode and IR LED, while the other simply had these lenses gunked up with spilled coffee. Of course, getting to this lens assembly still required a full machine teardown, making cleaning it an arduous task.

Unfortunately the machine that had the missing lens assembly turned out to have another fault which even after hours of debugging remained elusive, but at least there was one working coffee machine afterwards to make a cup of joe to make [Mark] feel slightly better about his life choices. As for why the lens assembly was missing, it’s quite possible that someone else tried to repair the original fault, didn’t find it, and reassembled the machine without the lens before passing the problem on to the next victim.

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Reverse-Engineering The Tamagotchi IR Connection

January 10, 2026 by Maya Posch 7 Comments

The Tamagotchi Connection is a series of Tamagotchi toys that took the original portable pet concept and mixed things up with a wireless connection, which allowed you to interact with the pets of other proud Tamagotchi owners. This wireless connection is implemented using an infrared transceiver, somewhat like IrDA, but as [Zach Resmer] discovered while reverse-engineering this connection, it’s actually what is called ‘Nearly NEC’ by [Natalie Silvanovich], who has a GitHub repository full of related Tamagotchi hacking tools and ROM dumps.

With the protocol figured out, creating a transceiver for low-bitrate infrared communication isn’t particularly hard. In this case, it was implemented using an RP2040 MCU and an appropriate IR LED and receiver pair. This Tamagometer project was also implemented as an app for the Flipper Zero, and a custom PCB called the Pico TamaBadge by [Daniel Weidman].

There’s a web application associated with [Zach]’s project using a Web Serial-enabled browser (i.e. Chrome). The serial protocol is somewhat documented in the patent for the device’s connection feature, which makes it relatively easy to implement yourself.

Reverse-Engineering The Intel 8087 Stack Circuitry

December 19, 2025 by Maya Posch 3 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.

Reverse Sundial Still Tells Time

December 10, 2025 by Tyler August 11 Comments

The Dutch word for sundial, zonnewijzer, can be literally translated into “Sun Pointer” according to [illusionmanager] — and he took that literal translation literally, building a reverse sundial so he would always know the precise location of our local star, even when it is occluded by clouds or the rest of the planet.

The electronics aren’t hugely complicated: an ESP32 dev board, an RTC board, and a couple of steppers. But the craftsmanship is, as usual for [illusionmanager], impeccable. You might guess that one motor controls the altitude and the other the azimuth of the LED-filament pointer (a neat find from AliExpress), but you’d be wrong.

This is more like an equatorial mount, in that the shaft the arrow spins upon is bent at a 23.5 degree angle. Through that hollow shaft a spring-steel wire connects the arrow to one stepper, to drive it through the day. The second stepper turns the shaft to keep the axis pointed correctly as Earth orbits the sun. See the demo video embedded below for full details.

Either way you can get an arrow that always points at the sun, but this is lot more elegant than an alt-az mount would have been, at the expense of a fiddlier build. Given the existence of the orrery clock we featured from him previously, it’s safe to say that [illusionmanager] is not afraid of a fiddly build. Doing it this way also lets you read the ticks on the base just as you would a real sundial, which takes this from discussion piece to (semi) usable clock.

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Reverse Engineering The Miele Diagnostic Interface

November 17, 2025 by Maya Posch 22 Comments

Since modern household appliances now have an MCU inside, they often have a diagnostic interface and — sometimes — more. Case in point: Miele washing machines, like the one that [Severin] recently fixed, leading to the firmware becoming unhappy and refusing to work. This fortunately turned out to be recoverable by clearing the MCU’s fault memory, but if you’re unlucky, you will have to recalibrate the machine, which requires very special and proprietary software.

Naturally, this led [Severin] down the path of investigating how exactly the Miele Diagnostic Utility (MDU) and the Program Correction (PC) interface communicate. Interestingly, the PC interface uses an infrared LED/receiver combination that’s often combined with a status LED, as indicated by a ‘PC’ symbol. This interface uses the well-known IrDA standard, but [Severin] still had to track down the serial protocol.

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2025 Component Abuse Challenge: Reverse Biasing An NPN BJT

November 6, 2025 by John Elliot V 10 Comments

For the Component Abuse Challenge our hacker [Tim Williams] observes that N-P-N reads the same way forwards and backwards, so… what happens if we reverse bias one? (Note: this remark about N-P-N reading the same forward and backward is a lighthearted joke; in fact the level of doping in the emitter and collector is different so those Ns are not fungible and will exhibit different properties and have different characteristics.)

In the margin you can see how the question was originally posed by Bob Pease back in March 18, 1996.

In his article [Tim] mentions that some transistors are specifically designed to operate when reverse biased, which [Tim] calls “inverted mode”, whereas most transistors are not designed to work in this fashion and that’s the sort of abuse that could damage the component and lead it to malfunction.

But what is V_out? [Tim] reports that he measured approximately -0.4 volts using his high-impedance meter. We tried this experiment in the lab ourselves but we were not able to duplicate [Tim]’s result; however there is a long list of potential reasons for such an outcome. If you do this experiment yourself we would love to hear about your results in the comments section!

If you’re still learning about transistors you might like to check out our five part series on transistors as amplifiers, starting here: Won’t Somebody, Please, Think Of The Transistors!

Thanks to [Tim] for his submission, we wish him the best of luck in the competition!

Reverse Engineering STL Files With FreeCAD

October 21, 2025 by Al Williams 30 Comments

If you think about it, STL files are like PDF files. You usually create them using some other program, export them, and then expect them to print. But you rarely do serious editing on a PDF or an STL. But what if you don’t have anything but the STL? [The Savvy Engineer] has a method to help you if you need to reverse engineer an STL file in FreeCAD. Check it out in the video below.

The problem is, of course, that STLs are made up of numerous little triangles. The trick is to switch workbenches and create a shape from mesh. That gets you part of the way.

Once you have a shape, you can convert it to a solid. At that point, you can create a refined copy. This gives you a proper CAD file that you can export to a STEP file. From there, you can use it in FreeCAD or nearly any other CAD package you like to use.

Once you have a proper object, you can easily use it like any other solid body in your CAD program. This is one of those things you won’t need every day, but when you do need it, it’ll come in handy.

Want to up your FreeCAD game? We can help. There are other ways to hack up STL files. You can even import them into TinkerCAD to do simple things, but they still aren’t proper objects.

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