Calipers: Do You Get What You Pay For?

August 11, 2025 by 53 Comments

Generally, you think that if you pay more for something, it must be better, right? But that’s not always true. Even if it is true at the lower end, sometimes premium brands are just barely better than the midrange. [Project Farm] looks at a bunch of different calipers — a constant fixture around the shop if you do any machining, 3D printing, or PCB layout. The price range spans from less than $10 for some Harbor Freight specials to brands like Mitutoyo, which cost well over $100. Where’s the sweet spot? See the video below to find out.

The first part of the video covers how much the units weigh, how smooth the action is, and how much force it takes to push it down. However, those are not what you probably care most about. The real questions are how accurate and repeatable they are.

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Neon Bulbs? They’re A Gas!

August 11, 2025 by 39 Comments

When you think of neon, you might think of neon signs or the tenth element, a noble gas. But there was a time when neon bulbs like the venerable NE-2 were the 555 of their day, with a seemingly endless number of clever circuits. What made this little device so versatile? And why do we see so few of them today?

Neon’s brilliant glow was noted when William Ramsay and Morris Travers discovered it in 1898. It would be 1910 before a practical lighting device using neon appeared. It was 1915 when the developer, Georges Claude, of Air Liquide fame, received a patent on the unique electrodes suitable for lighting and, thus, had a monopoly on the technology he sold through his company Claude Neon Lights.

However, Daniel Moore in 1917 developed a different kind of neon bulb while working for General Electric. These bulbs used coronal discharge to produce a red glow or, with argon, a blue glow. This was different enough to earn another patent, and neon bulbs found use primarily as indicator lamps before the advent of the LED. However, it would also find many other uses.

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Smartphone Hackability, Or, A Pocket Computer That Isn’t

August 11, 2025 by 88 Comments

Smartphones boggle my mind a whole lot – they’re pocket computers, with heaps of power to spare, and yet they feel like the furthest from it. As far as personal computers go, smartphones are surprisingly user-hostile.

In the last year’s time, even my YouTube recommendations are full of people, mostly millennials, talking about technology these days being uninspiring. In many of those videos, people will talk about phones and the ecosystems that they create, and even if they mostly talk about the symptoms rather than root causes, the overall mood is pretty clear – tech got bland, even the kinds of pocket tech you’d consider marvellous in abstract. It goes deeper than cell phones all looking alike, though. They all behave alike, to our detriment.

A thought-provoking exercise is to try to compare smartphone development timelines to those of home PCs, and see just in which ways the timelines diverged, which forces acted upon which aspect of the tech at what points, and how that impacted the alienation people feel when interacting with either of these devices long-term. You’ll see some major trends – lack of standardization through proprietary technology calling the shots, stifling of innovation both knowingly and unknowingly, and finance-first development as opposed to long-term investments.

Let’s start with a fun aspect, and that is hackability. It’s not perceived to be a significant driver of change, but I do believe it to be severely decreasing chances of regular people tinkering with their phones to any amount of success. In other words, if you can’t hack it in small ways, you can’t really make it yours.

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Jenny’s Daily Drivers: FreeDOS 1.4

August 6, 2025 by 67 Comments

When I was a student, I was a diehard Commodore Amiga user, having upgraded to an A500+ from my Sinclair Spectrum. The Amiga could do it all, it became my programming environment for electronic engineering course work, my audio workstation for student radio, my gaming hub, and much more.

One thing that was part of my course work it couldn’t do very well, which was be exactly like the PCs in my university’s lab. I feel old when I reflect that it’s 35 years ago, and remember sitting down in front of a Tulip PC-XT clone to compile my C code written on the Amiga. Eventually I cobbled together a 286 from cast-off parts, and entered the PC age. Alongside the Amiga it felt like a retrograde step, but mastering DOS 3.3 was arguably more useful to my career than AmigaDOS.

It’s DOS, But It’s Not MS-DOS

The FreeDOS installation screen
Where do I want to go today?

I don’t think I’ve used a pure DOS machine as anything but an occasional retrocomputing curio since some time in the late 1990s, because the Microsoft world long ago headed off into Windows country while I’ve been a Linux user for a very long time. But DOS hasn’t gone away even if Microsoft left it behind, because the FreeDOS project have created an entirely open-source replacement. It’s not MS-DOS, but it’s DOS. It does everything the way your old machine did, but in a lot of cases better and faster. Can I use it as one of my Daily Drivers here in the 2020s? There is only one way to find out.

With few exceptions, an important part of using an OS for this series is to run it on real hardware rather than an emulator. To that end I fished out my lowest-spec PC, a 2010 HP Mini 10 netbook that I hold onto for sentimental reasons. With a 1.6 GHz single core 32 bit Atom processor and a couple of gigabytes of memory it’s a very slow machine for modern desktop Linux, but given that FreeDOS can run on even the earliest PCs it’s a DOS powerhouse. To make it even more ridiculously overspecified I put a 2.5″ SSD in it, and downloaded the FreeDOS USB installer image. Continue reading “Jenny’s Daily Drivers: FreeDOS 1.4” →

A filament extruder is shown on a workbench. On the front is a knob and the display of a PID controller. A black geared spool is mounted on the top of the extruder, and on the right, a clear plastic bottle is positioned over a metal rod.

Turning Waste Plastic Into Spools Of Filament

August 1, 2025 by 28 Comments

Despite being a readily-available source of useful plastic, massive numbers of disposable bottles go to waste every day. To remedy this problem (or take advantage of this situation, depending on your perspective) [Igor Tylman] created the PETmachine, an extruder to make 3D printer filament from PET plastic bottles.

The design of the extruder is fairly standard for such machines: a knife mounted to the frame slices the bottle into one long strip, which feeds through a heated extruder onto a spool which pulls the plastic strand through the system. This design stands out, though, in its documentation and ease of assembly. The detailed assembly guides, diagrams, and the lack of crimped or soldered connections all make it evident that this was designed to be built in a classroom. The filament produced is of respectable quality: 1.75 mm diameter, usually within a tolerance of 0.05 mm, as long as the extruder’s temperature and the spool’s speed were properly calibrated. However, printing with the filament does require an all-metal hotend capable of 270 ℃, and a dual-drive extruder is recommended.

One issue with the extruder is that each bottle only produces a short strand of filament, which isn’t sufficient for printing larger objects. Thus, [Igor] also created a filament welder and a spooling machine. The welder uses an induction coil to heat up a steel tube, inside of which the ends of the filament sections are pressed together to create a bond. The filament winder, for its part, can wind with adjustable speed and tension, and uses a moving guide to distribute the filament evenly across the spool, avoiding tangles.

If you’re interested in this kind of extruder, we’ve covered a number of similar designs in the past. The variety of filament welders, however, is a bit more limited.

Thanks to [RomanMal] for the tip!

One Man’s Trash… Bicycle Edition

July 30, 2025 by 2 Comments

[Remy van Elst] found an obsolete bike navigation system, the Navman Bike 1000, in a thrift store for €10. The device was a rebadged Mio Cyclo 200 from 2015. Can a decade-old GPS be useful? Well, the answer depends on a little reverse engineering.

There were some newer maps available, but they wouldn’t download using the official software. Out comes WireShark and mitmproxy. That allowed [Remy] to eavesdrop on what was going on between the box and its home server. From there he could intercept the downloaded software image, which in turn yielded to scrutiny. There was one executable, but since the device mounted as a drive, he was able to rename that executable and put his own in using the same name.

The device turns out to run Windows CE. It could even run DOOM! Once he was into the box with a file manager, it was fairly straightforward to add newer software and even update the maps using OpenStreetMaps.

This is a great example of how a little ingenuity and open source tools can extend the life of consumer electronics. It isn’t always as easy to find an entry point into some device like this. Then again, sometimes it’s a little easier than maybe it should be.

We’d all but forgotten Windows CE. We see many people using WireShark, but fewer running mitmproxy. It sure is useful.

Power Line Patrols: The Grid’s Eye In The Sky

July 29, 2025 by 18 Comments

Those of us who like to monitor air traffic with ADS-B aggregators such as FlightAware and ADS-B Exchange tend to see some interesting flight paths. I’m not talking about the truly ambitious pictures drawn by pilots, or even the more ribald ones, but rather flights that follow paths that seem to make little sense from either a commercial or leisure standpoint.

Most of these mystery flights have long straight stretches interrupted by occasional tight loops, and often cover great distances across rural and urban landscapes alike. A glance at the ADS-B data indicates that these flights are usually pretty close to the ground, and are often completed by helicopters. Occasionally, the registration of the aircraft will even indicate ownership by some “three-letter” federal agency.

Although mystery helicopters flying odd patterns in the sky seems like a good excuse to don a tinfoil hat and head to one’s bunker, chances are pretty good that these aircraft are engaged in a far less nefarious and far more useful endeavour: aerial transmission line patrols. These flights are key to keeping the transmission lines that form the backbone of the grid in tip-top shape, especially at a time of unprecedented growth in load and a shift in the generation profile away from fossil fuels towards renewables.

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