This week Jonathan chats with benny Vasquez about AlmaLinux! Why is AlmaLinux the choice for slightly older hardware? What is the deal with RISC-V? And how does EPEL fit in? Tune in to find out!
Continue reading “FLOSS Weekly Episode 839: I Want To Get Paid Twice”
In Greek mythology, Sisyphus was a figure who was doomed to roll a boulder for eternity as a punishment from the gods. Inspired by this, [Aidan], [Jorge], and [Henry] decided to build a sand-drawing table that endlessly traces out beautiful patterns (or at least, for as long as power is applied). You can watch it go in the video below.
The project was undertaken as part of the trio’s work for the ECE4760 class at Cornell. A Raspberry Pi Pico runs the show, using TMC2209 drivers to command a pair of NEMA17 stepper motors to drag a magnet around beneath the sand. The build is based around a polar coordinate system, with one stepper motor rotating an arm under the table, and another panning the magnet back and forth along its length. This setup is well-suited to the round sand pit on top of the table, made with a laser-cut wooden ring affixed to a thick base plate.
The trio does a great job explaining the hardware and software decisions made, as well as showing off how everything works in great detail. If you desire to build a sand table of your own, you would do well to start here. Or, you could explore some of the many other sand table projects we’ve featured over the years.
The Raspberry Pi has been used for many things over its lifetime, and we’re guessing that many of you will have one in perhaps its most common configuration, as a small server. [Thibault] has a Pi 4 in this role, and it’s used to back up the data from his VPS in a data centre. The Pi 4 may be small and relatively affordable, but it’s no slouch in computing terms, so he was extremely surprised to see it showing a transfer speed in bytes per second rather than kilobytes or megabytes. What was up? He set out to find the bottleneck.
We’re treated to a methodical step-through of all the constituent parts of the infrastructure between the data centre and the disk, and all of them show the speeds expected. Eventually, the focus shifts to the encryption he’s using, both on the USB disk connected to the Pi and within the backup program he’s using. As it turns out, while the Pi is good at many things, encryption is not its strong point. Some work with htop shows the cores maxed out as it tries to work with encrypted data, and he’s found the bottleneck.
To show just how useful a Pi server can be without the encryption, we’re using an early model to crunch a massive language corpus.
Header image: macrophile, CC BY 2.0.
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.
Continue reading “Pictures From Paper Reflections And A Single Pixel”
The humble piezo element is often used as little more than a buzzer in many projects. However, you can do more with them, as [Something Physical] demonstrates with their nifty piezo noise box. Check out the video (and audio) below.
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.
Time for another European flavoured Hackaday Podcast this week, as Elliot Williams is joined by Jenny List, two writers sweltering in the humidity of a Central European summer. Both of our fans and air conditioners made enough noise to be picked up on the microphone when they were turned on, so we’re suffering for your entertainment.
The big Hackaday news stories of the week are twofold, firstly a cat-themed set of winners for the 2025 Pet Hacks contest, and then the announcement of a fresh competition: the 2025 Hackaday One Hertz Challenge. Get your once-a-second projects ready!
This week gave us a nice pile of interesting hacks, including some next-level work growing and machining the crystal for a home-made Pockels cell light valve, an upcoming technique for glass 3D prints, and enough vulnerabilities to make any Nissan Leaf owner nervous. We note that mechanical 7-segment displays are an arena showing excellent hacks, and we’re here for it.
Meanwhile among the quick hacks a filament made of PLA with a PETG core caught Elliot’s eye, while Jenny was impressed with a beautifully-made paper tape punch. Finally in the can’t miss section, The latest in Dan Maloney’s Mining and Refining series looks at drilling and blasting. Such an explosive piece should come last, but wait! There’s more! Al Williams gives us a potted history of satellite phones, and explains why you don’t carry an Iridium in your pocket.
Or download it your own fine self. MP3 for free!
[Ralph] is excited about impedance matching, and why not? It is important to match the source and load impedance to get the most power out of a circuit. He’s got a whole series of videos about it. The latest? Matching using a PI network and the venerable Smith Chart.
We like that he makes each video self-contained. It does mean if you watch them all, you get some review, but that’s not a bad thing, really. He also does a great job of outlining simple concepts, such as what a complex conjugate is, that you might have forgotten.
