Image

Making An Air-Powered Circular Saw With LEGO

The all-LEGO version barely cuts paper. (Credit: Jamie's Brick Jams, YouTube)
The all-LEGO version barely cuts paper. (Credit: Jamie’s Brick Jams, YouTube)

Although building a table saw out of LEGO is probably not the first thing that comes to mind when you look at those colorful bits of plastic, [Jamie] has been on a bit of a search for more applications of his LEGO-based air-powered motors. Naturally this led to the idea of doing something useful with it, like making a table saw you can actually use for real wood.

Starting off with a basic prototype using only regular LEGO pieces to get the mechanism figured out, [Jamie] then builds this up into said air-powered table saw featuring an actual metal blade. Suffice it to say that this isn’t something that you want your children to do with their LEGO while unsupervised.

The star of the show is of course the air-powered turbine that spins the blade. This is something that [Jamie] has been working on for a while, going through a number of prototypes to figure out a 3D printed geometry for the turbine blade that helps to convert as much of the high-pressure air into rotation.

Along the way it was also discovered that 3D printing saw blades is pretty hard, probably due to the lack of a sharp edge. This is definitely an area where it’s hard to beat a real table saw blade, with the added caveat that anything that’s good at cutting up boards of wood and sausages will just as happy slice through careless primate fingers.

In terms of safety features, the air supply is cut automatically with a sort of dead-man switch that requires you to keep one hand on it while using the final table saw design. There also an auto-feeding system added that tries to guide the board into the saw, but this turned out to be finicky. Suffice it to say that an air compressor and a handful of non-LEGO-approved components created a pretty convincing table saw.

Continue reading “Making An Air-Powered Circular Saw With LEGO”

Image

Looking At A TRS-80 12 MB External Hard Drive From 1983

Although hard disks weren’t a common feature yet in many home computers in the 1980s, they were becoming increasingly more affordable. For relative meanings of the word ‘affordable’, naturally. This is illustrated by the 12 MB HDD for the Radio Shack TRS-80 that [Clint] over at LGR recently took a peek at.

Image

Costing a cool $3,495 in 1983 – or $11,932 in 2026 USD – this 12 MB storage wonder used a Tandon TM-603 full-height 5.25″ HDD inside. Lacking a working TRS-80 to try it out with, the video is limited to just a basic powering up and opening up of the unit, but [Clint] will be donating it to a computer museum who can hopefully put it to use again.

The connection to the TRS-80 computer is handled by a ribbon cable, while the HDD has its own built-in power supply, rated at 60 Watt.

On the main board for the external HDD controller there is a Signetics 8X300 microprocessor that forms the brains of what makes it into an external drive for the TRS-80. Despite its age, it still looks brand new inside, so despite the Rifa capacitors in the PSU, [Clint] decided to power it on. This resulted in an auditory experience that’s probably best compared to a very rusty jet engine spinning up after languishing for a decade prior to spooling up for take-off.

Hopefully we’ll find out whether this particular unit and its HDD are still working in 2026.

Continue reading “Looking At A TRS-80 12 MB External Hard Drive From 1983”

Image

Trying To Fix A Suspiciously Cheap Enterprise-Grade Network Switch

ImageWhen you see a listing for an Ethernet switch whose specification list is in effect ‘yes’, with a four-digit price tag when new, and with the seller asking for less than 10% of said $3,000 asking price in an ‘untested’ condition, the only rational thing to do is of course to mash that ‘buy’ button. This is what [This Does Not Compute] did, and created a video about to show what a great investment decision this was.

Naturally this Juniper EX4100-F-12P switch came without power supply brick for its 48VDC input. Figuring out its pin-out and probing said input showed that the voltage rails had been shorted, giving a first clue as to why this switch had been on sale for so very cheap. Bravely hoping that it would be a straightforward fix, the unit was disassembled.

With a 280 Watt power brick, it’s little wonder that the top of the unit is a one massive aluminium heatsink, including a large heatpipe. Also visible on the lid near the power input was a very-bad-news black skid mark.

From that first discovery the news just got worse and worse, with clear signs of water ingression, rust and corrosion, along with the aftermath of a powered circuit meeting such bad corrosion. After some clean-up it’s clear that some components had violently exploded, ripping apart layers of the PCB and likely parts of traces in those inner sections too.

With no schematics available and no other good repair options via Juniper or anywhere else, it seems that unfortunately this gamble turned out to be merely a pile of e-waste and a few bucks worth of scrap metal. Caveat emptor, once more.

Continue reading “Trying To Fix A Suspiciously Cheap Enterprise-Grade Network Switch”

Image

Making A Neo Nuvistor Project In 2026

ImageFor a little while vacuum tubes and semiconductors were fighting a heated battle for dominance, with bipolar junction transistors and 1959’s RCA Nuvistor both allowing you to build a compact circuit with relatively low power usage and no high voltages. Although we now know that semiconductor technology won out overwhelmingly, that doesn’t mean that you cannot build a brand new Nuvistor board in 2026, as [Eric Schlaepfer] AKA [TubeTimeUS] recently did.

Nuvistors saw their most use in small-signal radio frequency applications, like VHF and UHF, with excellent low-noise characteristics that saw them used until the early 1970s in television sets, radios and oscilloscopes, as well as in space probes like the 1960s US Ranger Moon missions, so by that metric they had a good run.

Nothing so exciting is built in this video, sadly, but alongside a breakdown on how nuvistors work, we do see a discrete 555-style timer built using a gaggle of tetrode nuvistors, giving a pretty good idea of what using them in a project is like. Being a vacuum tube at its core, nuvistors still have the heater element, which is what gives vacuum tubes their reputation for being slow to start working and large current draw.

Despite their drawbacks, nuvistors still have a range of benefits compared to modern-day transistors, including being practically immune to electrostatic discharge (ESD) and electromagnetic interference (EMI) all the way up an EMP that will destroy most semiconductor electronics.

That said, the somewhat limited 8-nuvistor implementation of the 555 had to get a few extra pins for the heater supply, which burns up about 7.5 Watt just to allow the circuit to function. Terming it the ‘hollow-state 555 timer’, it works effectively just like any semiconductor 555, just with that extra power cost and of course no significant prospect of making it smaller, barring a semiconductor evolution as with the pixels-sized CRTs in the SED and FED type displays.

We covered the nuvistor before, including a great reference on this device, and its history that was much longer than people often assume today, as well as the vacuum tubes we use every day in for example our microwaves.

Continue reading “Making A Neo Nuvistor Project In 2026”

Image

Changing Nozzle Internal Geometry To Increase FDM Flowrate

ImageAs FDM printers keep getting faster, we are forced to deal with a range of bottlenecks, all of which conspire to hold us back from another Benchie world record. A major physical limitation is that of flowrate, as the hotend has to be able to melt the filament that enters the nozzle before it departs said nozzle. One attempt to make a high-flow nozzle involves splitting the material path into three winding sections, which theoretically should help said flowrate. Recently [Thomas Sanladerer] took a poke at this and other types of nozzle with SLS-printed nozzles.

These printed parts still needed some finishing on the lathe, including drilling the 0.4 mm nozzle hole. The finished nozzles feature a variety of internal geometries, including the aforementioned triple-path, as well as many with various intrusions that seek to maximize the contact area.

Using a Prusa Core One these nozzles were subsequently tested to see what print quality they produced at high flow rates. A special test rig to test the nozzle pressure was also used to further characterize them, as this indicates at which flowrate the nozzle begins to struggle. Among these the Fuge design did the best, though with the big asterisk that these nozzles were printed in MS1, which is in effect tool steel and thus not great for being nozzles.

Continue reading “Changing Nozzle Internal Geometry To Increase FDM Flowrate”

Image

Creating A Custom Hinge For A Motorbike’s Fuel Access Panel

ImageA fun part of modifying something like a motorbike is that you sometimes have to come up with creative solutions to basic questions, like how you can still access the fuel tank’s cap after extending it forward. In the case of [KRTframework] this meant that the fuel cap was now underneath the bodywork, requiring a suitable way to access it. Of course, this meant making a hidden access panel with a custom hinge, to not break the bike’s clean lines.

To make the process as easy as possible, a 3D scanner was used to get detailed measurements on what the new bodywork would look like. Using these the new bodywork was created, including what would be the hidden access panel, yet finding a suitable hinge mechanism wasn’t easy. This is where this custom design was created, with detailed assembly covered in the video.

To bridge the gap between the opening and the fuel tank a part was 3D-printed that also contains the simple push-to-open latch mechanism. Of course, in the comment section people sounded off on this, feeling that it would be far too easy to accidentally open the panel.

The hinge seems to be well-received at least, with it having to fit within the available space, while also providing good access to the fuel cap when opened, meaning quite a lot of travel.

Continue reading “Creating A Custom Hinge For A Motorbike’s Fuel Access Panel”

Image

Decoding The NEC V20 Microcode ROM

The NEC V20 is an Intel 8088-compatible processor that features the same use of microcode, though with its own characteristics. This makes it important to use this same microcode if your goal is to create a cycle-accurate emulator of this processor, as [GloriousCow]’s goal is. Cue decoding the microcode ROM in a die shot of this CPU, in order to create a usable ROM image.

As with any fabricated ROM you can technically do it by hand, the ROM section in the die shot contained 29,928 bits which even at a pretty zippy pace would take up a considerable amount of time to parse. Here you can divide-and-conquer by handing parts of the ROM off to good friends, or you can use automation and some machine vision and theoretically get an answer as soon as you have finished writing and testing the tool.

Close-up of some of the microcode bits.
Close-up of some of the microcode bits.

Although [Travis Goodspeed]’s MaskRomTool exists exactly to automate bit detection, it was found that there wasn’t enough contrast in the die shot for it to work reliably. What it did provide were the locations of the bits and from it 42×42 pixel PNG files of each bit.

Next a convolutional neural network (CNN) was trained to determine the difference between a 0 and 1 bit. This still took the manual classifying of 1,000 images, but seemed to work fairly well. Although some bits were marked as ambiguous, it was easy enough to use Mark 1 eyeballs to run a classification on these handful of images than to tweak the CNN model.

With this microcode in hand it was then possible to match it against the V20’s internal architecture to fully determine what each part does. Although not quite finished yet, there’s a GitHub repository containing the progress so far.

The V20’s microcode has been the focal point of much legal fighting back when NEC and Intel were still duking it out in how far one could make a CPU compatible with that of a competitor.