If you’re coming to Hackaday Europe 2025, you’ve got just over a week to get your bags packed and head on out to Berlin. Of course you have tickets already, right? And if you were still on the fence, let us tempt you with our keynote talk and some news about the Friday night meetup, sponsored by Crowd Supply.
We’ll take a guess that most readers have a set of digital calipers somewhere close to hand right now. The cheapest ones tend to be a little unsatisfying in the hand, a bit crusty and crunchy to use. But as [Matthias Wandel] shows us, these budget tools are quite hackable and a lot more precise than they appear to be.
[Matthias] is perhaps best known around these parts for making machine tools using mainly wood. It’s an unconventional material for things like the CNC router he loves to hate, but he makes it work through a combination of clever engineering and a willingness to work within the limits of the machine. To assess those limits, he connected some cheap digital calipers to a Raspberry Pi by hacking the serial interface that seems to be built into all of these tools. His particular calipers output a pair of 24-bit words over a synchronous serial connection a couple of times per second, but at a level too low to be read by the Pi. He solved this with a clever resistor ladder to shift the signals to straddle the 1.8 volt transition on the Pi, and after solving some noise problems with a few strategically placed capacitors and some software debouncing, he was gathering data on his Pi.
Although his setup was fine for the measurements he needed to make, [Matthias] couldn’t help falling down the rabbit hole of trying to milk better resolution from the calipers. On paper, the 24-bit output should provide micron-ish resolution, but sadly, the readings seem to fluctuate rapidly between two levels, making it difficult to obtain an average quickly enough to be useful. Still, it’s a good exercise, and overall, these hacks should prove handy for anyone who wants to dip a toe into automated metrology on a budget.
Continue reading “Hacking Digital Calipers For Automated Measurements And Sorta-Micron Accuracy”
If you came of age in the 1990s, you’ll remember the unmistakable auditory handshake of an analog modem negotiating its connection via the plain old telephone system. That cacophony of screeches and hisses was the result of careful engineering. They allowed digital data to travel down phone lines that were only ever built to carry audio—and pretty crummy audio, at that.
Speeds crept up over the years, eventually reaching 33.6 kbps—thought to be the practical limit for audio modems running over the telephone network. Yet, hindsight tells us that 56k modems eventually became the norm! It was all thanks to some lateral thinking which made the most of the what the 1990s phone network had to offer.
Continue reading “Why 56k Modems Relied On Digital Phone Lines You Didn’t Know We Had”
If you’re familiar with Java here in 2025, the programming language you know is a world away from what Sun Microsystems planned for it in the mid-1990s. Back then it was key to a bright coffee-themed future of write-once-run-anywhere software, and aside from your web browser using it to run applications, your computer would be a diskless workstation running Java bytecode natively on the silicon.
What we got was slow and disappointing Java applets in web pages, and a line of cut-down SPARC-based JavaStations which did nothing to change the world. [FatSquirrel] has one of these machines, and a quarter century later, has it running NetBSD. It’s an interesting journey both into 1990s tech, and some modern-day networking tricks to make it happen.
These machines suffer as might be expected, from exhausted memory backup batteries. Fortunately once the serial port has been figured out they drop you into an OpenBoot prompt, which, in common with Apple machines in the ’90s, gives you a Forth interpreter. There’s enough info online to load the NVRAM with a config, and the machine stuttered into life. To do anything useful takes a network with RARP and NFS to serve an IP address and disk image respectively, which a modern Linux machine is quite happy to do. The resulting NetBSD machine maybe isn’t as useful as it could be, but at risk of angering any Java enthusiasts, perhaps it’s more useful than the original JavaOS.
We remember the promise of a Java-based future too, and tasted the bitter disappointment of stuttering Java applets in our web pages. However, given that so much of what we use now quietly runs Java in the background without our noticing it, perhaps the shade of Sun Microsystems had the last laugh after all. This isn’t the first ’90s machine that’s been taught new tricks here, some of them have received Java for the first time.
For those who love systems and structure, owning a 19-inch rack with just one slot filled is just not it. But what if the rest of your gear isn’t 19-inch? Well, then you go out and make it so, just like [Cal Bryant] did recently.
The goal was to consolidate multiple devices — DAC, input selector, streamer, and power routing — into a single 2U rackmount unit. His first attempts involved drilling 1U panels to attach gear with removable faceplates. That worked, but not all devices played nice. So his next step became a fully custom enclosure with CAD-modeled brackets and front panels.
OpenSCAD turned out to be a lifesaver, letting [Cal] design modular mounting solutions. Exporting proper circles for CNC turret punching however appeared to be a nightmare. It was FreeCAD to the rescue for post-processing. After some sanding and auto-shop painting, the final faceplate looked factory-made.
Custom switch boxes for power and audio routing keep things tidy, housing everything from USB to XLR inputs. A 4-pole switch even allows seamless swapping between his DAC and DJ controller, while UV-printed graphics bring the finishing touch to this project. For those looking to clean up their Hi-Fi setup (or just love modding for the sake of it), there’s a lot to learn from this build.
If buying a rack is not within your budget, you could start with well-known IKEA LACK furniture.
It’s something of a surprise, should you own a CRT TV to go with your retrocomputers, when you use it to view a film or a TV show. The resolution may be old-fashioned, but the colors jump out at you, in a way you’d forgotten CRTs could do. You’re seeing black levels that LCD screens can’t match, and which you’ll only find comparable on a modern OLED TVs. Can an LCD screen achieve decent black levels? [DIY Perks] is here with a modified screen that does just that.
LCD screens work by placing a set of electronic polarizing filters in front of a bright light. Bright pixels let through the light, while black pixels, well, they do their best, but a bit of light gets through. As a result, they have washed-out blacks, and their images aren’t as crisp and high contrast as they should be. More modern LCDs use an array of LEDs as the backlight which they illuminate as a low resolution version of the image, an approach which improves matters but leaves a “halo” round bright spots.
The TV in the video below the break is an older LCD set, from which he removes the backlight and places the electronics in a stand. He can show an image on it by placing a lamp behind it, but he does something much cleverer. An old DLP projector with its color wheel removed projects a high-res luminance map onto the back of the screen, resulting in the coveted high contrast image. The final result uses a somewhat unwieldy mirror arrangement to shorten the distance for the projector, but we love this hack. It’s not the first backlight hack we’ve seen, but perhaps it give the best result.
Continue reading “A TV With Contrast You Haven’t Seen For Years”
Nowadays, if you have a microscope, you probably have a camera of some sort attached. [Applied Science] shows how you can add an array of tiny LEDs and some compute power to produce high-resolution images — higher than you can get with the microscope on its own. The idea is to illuminate each LED in the array individually and take a picture. Then, an algorithm constructs a higher-resolution image from the collected images. You can see the results and an explanation in the video below.
You’d think you could use this to enhance a cheap microscope, but the truth is you need a high-quality microscope to start with. In addition, color cameras may not be usable, so you may have to find or create a monochrome camera.
Continue reading “Ptychography For High Resolution Microscopy”
