Taking a picture with a single photoresistor is a brain-breaking idea. But go deeper and imagine taking that same picture with the same photoresistor, but without even facing the object. [Jon Bumstead] did exactly that with compressed sensing and a projector. Incredibly, the resulting image is from the perspective of the projector, not the “camera”.
This camera setup is very similar to one we’ve seen before, but far more capable. The only required electronics are a small projector and a single photodiode. The secret sauce in this particular design lies in the pattern projected and the algorithm to parse the data.
The construction is simple enough, attractive in its own way, with a rugged junk-assembly sort of style. The video starts out by demonstrating the use of a piezo element hooked up as a simple contact microphone, before developing it into something more eclectic.
The basic concept: Mount the piezo element to a metal box fitted with a variety of oddball implements. What kind of implements? Spiralled copper wires, a spring, and parts of a whisk. When struck, plucked, or twanged, they conduct vibrations through the box, the microphone picks them up, and the box passes the sound on to other audio equipment.
It might seem frivolous, but it’s got some real value for avant-garde musical experimentation. In particular, if you’re looking for weird signals to feed into your effects rack or modular synth setup, this is a great place to start.
The world of custom mechanical keyboards is vibrant, with new designs emerging weekly. However, keyboards are just one way we interact with computers. Ploopy, an open-source hardware company, focuses on innovative user interface devices. Recently, [Colin] from Ploopy introduced their latest creation: the Ploopy Knob, a compact and thoughtfully designed control device.
At first glance, the Ploopy Knob’s low-profile design may seem unassuming. Housed in a 3D-printed enclosure roughly the size of a large wristwatch, it contains a custom PCB powered by a USB-C connection. At its core, an RP2040 chip runs QMK firmware, enabling users to easily customize the knob’s functions.
The knob’s smooth rotation is achieved through a 6705ZZ bearing, which connects the top and bottom halves and spans nearly the device’s full width to eliminate wobble. Unlike traditional designs, the Ploopy Knob uses no mechanical encoder or potentiometer shaft. Instead, an AS5600 magnetic encoder detects movement with remarkable precision. This 12-bit rotary encoder can sense rotations as fine as 0.088 degrees, offering 4096 distinct positions for highly accurate control.
True to Ploopy’s philosophy, the Knob is fully open-source. On its GitHub Page, you’ll find everything from 3D-printed case files to RP2040 firmware, along with detailed guides for assembly and programming. This transparency empowers users to modify and build their own versions. Thanks to [Colin] for sharing this innovative device—we’re excited to see more open-source hardware from Ploopy. For those curious about other unique human-machine interfaces, check out our coverage of similar projects. Ploopy also has designs for trackballs (jump up a level on GitHub and you’ll see they have many interesting designs).
For over a decade, most passports have contained an NFC chip that holds a set of electronically readable data about the document and its holder. This has resulted in a much quicker passage through some borders as automatic barriers can replace human officials, but at the same time, it adds an opaque layer to the process. Just what data is on your passport, and can you read it for yourself? [Terence Eden] wanted to find out.
The write-up explains what’s on the passport and how to access it. Surprisingly, it’s a straightforward process, unlike, for example, the NFC on a bank card. Security against drive-by scanning is provided by the key being printed on the passport, requiring the passport to be physically opened.
Old hardware tends to get less support as the years go by, from both manufacturers and the open-source community alike. And yet, every now and then, we hear about fresh attention for an ancient device. Consider the ancient SoundBlaster sound card that first hit the market 31 years ago. [Mark] noticed that a recent update squashed a new bug on an old piece of gear.
Jump over to the Linux kernel archive, and you’ll find a pull request for v6.16-rc3 from [Takashi Iwai]. The update featured fixes for a number of sound devices, but one stands out amongst the rest. It’s the SoundBlaster AWE32 ISA sound card, with [Iwai] noting “we still got a bug report after 25 years.” The bug in question appears to have been reported in 2023 by a user running Fedora 39 on a 120 MHz Pentium-based machine.
The fixes themselves are not particularly interesting. They merely concern minutiae about the DMA modes used with the old hardware. The new updates ensure that DMA modes cannot be changed while the AWE32 is playing a PCM audio stream, and that DMA setups are disabled when changing modes. This helps avoid system lockups and/or ugly noises emanating from the output of the soundcard.
It’s incredibly unlikely this update will affect you, unless you’re one of a handful of users still using an ISA soundcard in 2025. Still, if you are — and good on you — you’ll be pleased someone still cares about your user experience. Meanwhile, if you’re aware of any other obscure old-school driver updates going on out there, don’t hesitate to let us know on the tips line. Want to relive your ISA card’s glory days? Plug it into USB.
The Ceran discs, freshly cut from the old stovetop and awaiting polishing. (Credit: Huygens Optics)
Ceran is a name brand for a type of glass ceramic that has a very low coefficient of thermal expansion (CTE). This is useful for stovetops, but it is also a highly desirable property for optical glass. The natural question: Can an old ceramic stovetop be upcycled into something visually striking? This is the topic of the most recent video in [Huygens Optics]’s series on glass ceramics.
Interestingly, by baking sections of the Ceran glass ceramic for 10 minutes at 961 °C, the CTE can be lowered by another five times, from 0.5 ppm / °C to a mere 0.1 ppm / °C. Following baking, you need a lot of grinding and polishing to remove any warping, existing textures, and printing. After polishing with 220 grit by hand for a few minutes, most of these issues were fixed, but for subsequent polishing, you want to use a machine to get the required nanometer-level precision, as well as to survive the six to eight hours of polishing.
Following this final polishing, the discs were ground into mirrors for a Newtonian telescope. This raised a small issue of the Ceran being only 4 mm thick, which requires doubling up two of the discs using a very thin layer of epoxy. After careful drilling, dodging cracked glass, and more polishing, this produced the world’s first ceramic stovetop upcycled into a telescope. We think it was the first, anyway. All that’s left is to coat the discs with a more reflective coating and install them into a telescope frame, but even in their raw state, they show the potential of this kind of material.
If you decide to try this, and you’ve already cut up your stove, you might as well attack some kitchen bowls, too.
If you’re unfamiliar with Beyblades, they’re a simple toy. They consist of spinning tops, which are designed to “fight” in arenas by knocking each other around. While the off-the-shelf models are deemed safe enough for children to play with, [Jon Bringus] decided to take the danger level up a few notches with some custom launchers of his own design.
[Jon]’s project started with some of the early metal Beyblades, which are traditionally launched with a small geared ripcord device. He soon realized he could up the action by doing one simple thing—spinning the tops far faster than the manufacturer ever intended. More rotational speed equals more kinetic energy equals more legal liability fun, or so the equation goes.
The design for [Jon’s] “WMD Launcher” is straightforward enough—he combined a lawnmower pull starter with a 12:1 geartrain to turn the Beyblades at truly ludicrous speeds. It’s basic engineering — a couple of 3D-printed gears do the job — but the results are hilarious. The tops begin to emit loud noises as they turn in combat, and some move so fast and erratically that they won’t even stay inside the arena. Protective eyewear is virtually mandatory. Files are on Printables for those eager to build one at home.
Yes, ruining a game of Beyblades is as simple as building an irresponsibly fast launcher. You needn’t even use some fancy brushless motor to hurt yourself — just a little gearing is enough to cause havoc. We’ve featured similar work on this topic before, too. Video after the break.
