2026-04-05 19:00:23
It’s a common ritual: whipping out those calipers or similar measuring devices to measure part of a physical object that we’re trying to transfer into a digital model in an application like FreeCAD. Wouldn’t it be nice if said measurements were to be transferred instantaneously into the model’s sketch, including appropriate units of measurement? That’s essentially what [stv0g] has done by merging a Sylvac Bluetooth-enabled caliper and FreeCAD using a plugin.
Key to the whole operation is a Bluetooth-enabled caliper like the Sylvac S_Cal EVO that [stv0g] managed to score on EBay for a mere €90 when it normally goes for multiple times that amount. This has BLE built in, using BLE’s standard GATT profiles for device communications specifications. Along with the provided Sylvac developer tools, this made it relatively easy to develop the InstrumentInput addon for FreeCAD.
This addon can be easily installed via FreeCAD’s addon manager as well, or if you wish to just use the calipers this way and don’t care about FreeCAD, the base Python library is also available.
Interestingly, this BLE-enabled caliper also supports HID mode, to emulate keyboard input, and thus it can work in any application by default. The reason why [stv0g] didn’t use this was that it only sends data when you press the caliper’s button, and it’s rather slow and limited.
Ever wonder what’s inside those calipers? We did too.
2026-04-05 16:00:04
Now that early PCs have moved firmly from the realm of e-waste into being collector’s items, it’s worth putting in some effort to restore them if you find one. [Epictronics] has an early IBM 5150, the ancestor of all today’s PCs, and is bringing it back to life. Along the way, he’s building a replica AdLib sound card, making a useful discovery about how to make new parts look authentic.
The video below the break is a gentle journey through an early PC teardown, followed by the construction of the replica sound card. Here’s the interesting nugget of information: these new cards are careful recreations of the originals, but they just don’t look right. It seems modern soldermask is too shiny, and as luck would have it, there’s another option that is much more period-authentic. We hadn’t noticed matte green was available, but it certainly captures the look of those days much better.
As you might expect, such an old machine has a range of dead capacitors and a few chips. There’s a lucky escape with a Varta battery on an expansion card, having very little leakage, and part of one of the floppy drives needs some surgery. It’s gentle hacking that’s engaging to watch, and of course, at the end, we’re rewarded with the thing booting properly.
You might think reproducing a sound card is unusual, but we’ve seen it a number of times.
2026-04-05 13:00:16
Many of us are guilty of toeing the line between having a ready supply of components at hand and simply hoarding for fear of throwing anything out. In a first admission of this problem, [Scott Lawson] decided to implement a couple of changes to assess his own position on this sliding scale.
The first change was to only put parts, components, and supplies in transparent boxes. Next was to add a sticker on each box noting the contents and box creation date. This was extended to plastic bags inside the boxes when further subdivision was warranted.
Next, the question was about usage patterns, as you may think that you know how often you use something from a specific box, or how important its contents are, but it helps to add some objectivity to this. For this, [Scott] used sheets of dot stickers, with a sticker added each time he opened a box and used something from it.
By persistently doing this for a few years at his home lab, [Scott] was able to assess which boxes fell into any of three categories: hot, warm, and cold. Cold boxes are very rarely — if ever — accessed, and can thus be readily moved to the attic, shed, or even sold off if they have spent a year or longer in cold storage. Hot boxes should obviously be kept near the work areas. This way, one can make objective decisions of what boxes should go where for optimal access, and what things in your home lab are basically just there to look pretty and gather dust.
This is an effective low-tech way to get organized. Or you can go the opposite direction.
2026-04-05 10:00:59
There were a plethora of tiny, local ISPs in the days of dial-up internet. Along with the big providers, many cities would have more than one. Some of those have survived broadband, but none of them were as small as [Jeff Geerling]’s Pi ISP — a tiny dialup ISP built so his Aunt’s old G3 MacBook can get online at 36kbps, as God and [Robert Khan] intended.
Hardware-wise, the Raspberry Pi is at one end of the chain, and your retrocomputer at another. In between, you’ll have a USB modem plugged into the Pi, and a device called a “two-way line simulator” to create a dial tone for that plain-old-telephone goodness. [Jeff] notes that these were commonly used in prisons for the phones that visitors use to talk to inmates.
Of course, since these devices are designed strictly for voice transmissions, which POTS was built for, you’re not going to get over 36 kbps, and that’s even with high-quality gear. The cheaper options might drop you down to 28k… just like with an ISP back in the day. ‘You get what you pay for’ is very rarely false.
Now, you can use this technology to just connect two computers together — as we’ve featured previously — but [Jeff] has gone the extra mile to put together, via Ansible, an easy-to-install software package that will let the Raspberry Pi act just like your ISP’s servers once did, and connect you to that series of tubes once called the World Wide Web. Of course, the World Wide Web isn’t built for dial-up anymore, so you’re going to be waiting… a while. Hackaday’s front page isn’t especially heavy, weighing about 4MB at the time of this writing, but that’s 15 minutes of load time, and you still aren’t reading the articles.
You also won’t be able to access much on old machines that can’t do HTTPS, but [Jeff] thought of that and bundles [rdmark]’s MacProxyClassic to translate the modern web into HTML tags that Netscape can understand and serve them over HTTP. You’ll still be waiting for our modern bloat, but perhaps not quite so long.
If you want the “authentic” dial-up experience, you’ll need to see the lightweight webpages of Yesteryear, and MacProxyClassic contains a Wayback Machine extension for that purpose. We featured a similar project a while back that did that, but without all the joys of dial-up. Now get off the computer, we’re expecting a call!
2026-04-05 07:00:17
From outer space to down here on Earth, there are many places where ionizing radiation levels are high enough that they effectively bar access for humans, but also make life miserable for anything containing semiconductor technology. This is especially true for anything involving wireless communications, such as Wi-Fi. However, recently Japanese researchers have created a Wi-Fi chip that is claimed to be so radiation-hardened that it can be used even in gamma ray-rich environments, such as in the worst contaminated depths of the Fukushima Daiichi nuclear reactor.
The indicated dose exposure of 500 kilograys that the chip survived during testing is quite significant. A single gray (Gy) is the absorption of one joule of energy per kilogram of matter. In radiation therapy, a solid epithelial tumor can receive as much as 60 to 80 Gy in a single dose, for example.
That this Wi-Fi chip was still able to function after such a large cumulative dose was therefore quite impressive, as it rivals what space-based probes receive over numerous years. Unfortunately, the research paper is paywalled, but the PR article from the Tokyo Institute of Science fills in a few more details along with the IEEE Spectrum article.
The key was reducing the number of transistors to offer as few targets for radiation as possible. Further inductors were used instead of transistors, for example, variable-gain, as these are less sensitive to ionizing radiation. Remaining transistors were physically enlarged, reducing the number of parallel segments and using NMOS transistors instead of PMOS, due to the latter’s higher radiation resistance.
Although degradation in receiver performance was observed after successive blasts at 300 kGy and then 500 kGy, the change was on the order of 1.5-1.6 dB. The next challenge is to make a Wi-Fi transmitter, which is much harder and may require the addition of materials like diamond.
Designing for a hostile radiation environment is an art form unto itself. And if you are generating radiation, you have to be extra careful.
2026-04-05 04:00:26
Every collector ends up with items that are worthless, usually because they are broken or incomplete. When [Graindead] found a 1920s glass-plate reflex camera for pennies with plenty of missing parts, it was obvious that what he had was a piece of junk. Throw it away? No, he turned it digital with the aid of a small document scanner.
A reflex camera like this one is the ancestor of the 35mm single-lens reflex cameras we may still be familiar with today, in that is has a flip-up mirror inside to bounce the light onto a ground glass screen. The photographer can see what the lens sees to set up the shot, before flipping the mirror out of the way and exposing the glass plate film by pulling out a dark slide. This one was missing the ground glass and the lens, so he has to grind a replacement, and bodge in a similar-age Carl Zeiss Tessar lens.
In the video below you can see the build, and a range of pictures including some trichrome colour shots. It gives an imperfect result even compared to the same camera with its period film, but the point here is the art rather than the clarity. We’d take this one out with us, if it were ours.
For more vintage digital fun, have a look at a similar adaptation that shoots video.
