It’s likely that even those of us who have never picked up a guitar in our lives will recognize the sound of an electric guitar with a fuzz box effects pedal. The raspy distorted sound has been at the heart of so many very well known recordings. Behind it is a distortion circuit, or as [Bill Jehle’s Mad Scientist Guitar Lab] is here to tell us, eight different circuit topologies.
The result is a fascinating trip through the evolution of rock music through the 1960s, as he examines circuits from simple diode clippers through to frequency doublers and phase shifters. He’s provided a playlist as an accompaniment so you can even have an immediate listen to each sound. It’ll mess up our YouTube recommendations, but worth it for the informative journey.
It’s also a window into a lost period in electronics where all they practically had was the transistor, so each device had to put in the maximum work for a living. Designing circuits like these called for intimate knowledge of the device characteristics, and just how they could be safely exceeded. The video is below the break, and well worth a watch.
Many pieces of consumer electronics are build down to a price, and the corners cut show up in their performance. The Gameboy Advance from Nintendo is no exception: its audio is a PWM stream that sounds awful through the included amplifier. [Cajun Panda] has a fix though, in the form of a replacement audio chain.
It takes the form of a PCB that hooks into the pads of the removed GBA audio chip, and provides a much cleaner audio path with filtering and EQ and a class D audio amplifier. In addition there’s an audio codec and an ESP32 for Bluetooth connectivity, enabled by a long press of a GBA button and configured via a web interface on the ESP. Best of all there is no case modification, this is designed to remain as stock as possible.
Everything can be found in a GitHub repository should you wish to make your own, so if you want to bring your GBA audio up to scratch you know where to go. If you want to make it even better don’t forget, you can always upgrade the screen.
If you’re blessed enough that you haven’t had blood drawn in a while, you might not have thought much about the process. You might imagine that a needle goes in, a syringe is drawn back, and the venous blood is thusly collected. Indeed, it can be done that way.
However, there is an altogether niftier and more efficient method of fast blood collection for pathology testing. It’s all about using vacuum and smart design to ease the work of phlebotomists, while maintaining a sterile and safe environment.
One of the fun aspects of open source software is that you can often find so many libraries and tools that implement the functionality you need, but ease of use for e.g. artists is often not a priority. This is where [Edin Spiegel] ‘s annoyances with photogrammetry tools led him down to the path of creating the Simple Photogrammetry GUI project, which is basically what it says on the tin.
In an associated video its development and use is demonstrated, combining tools like Colmap, OpenMVS, mvs-texturing, pymeshlab, brush and PoissonRecon to implement both photogrammetry and gaussian splatting to turn those photos into a not too shabby mesh along with realistic textures.
The GUI uses the Flutter GUI kit, so Linux support is still somewhat sketchy, but should work in this new release of this GUI wrapper. The author is asking for people to test this GUI and report any issues found so that they can be addressed.
From a quick glance at the project and the comments to the video it seems quite useful for anyone who wants to get started quickly with photogrammetry. One niggle is perhaps that it relies on processing using CUDA, with a much slower fallback to CPU processing if you do not happen to have an Nvidia-blessed GPU installed. Of course this is one of those universal issues in a world where theoretically everyone should be using OpenCL already.
In addition to the build instructions you can also download an AppImage for Linux and compiled binaries for Windows to theoretically get started as fast as your internet connection allows. Interestingly, the AppImage is well over a GB in size, whereas the Windows ZIP file is just 207 MB for the v1.1.5 release, so take that into account.
Last time we found out the idea of space stations is surprisingly old. By the 1950s, everyone knew we’d be working in beautiful space stations that rotated like a wheel to give us the illusion of gravity. Of course, that didn’t happen. But we did get some practical space stations, even before the current crop. The road to get there, though, was predictably bumpy.
Convair: From TASSEL to MARS
Convair had been studying multi-person orbital stations under Krafft Ehricke since the late 1950s. One result was TASSEL, an acronym for the Three Astronaut Space System Experimental Laboratory. Proposed in 1960, TASSEL was a three-man laboratory intended for an Atlas-Centaur launch into a roughly 200-nautical-mile orbit and missions lasting two or three weeks.
Around the same time, the Air Force asked contractors for proposals for a Military Test Space Station, or MTSS. Convair was one of five companies selected for the study in 1960. The surviving record suggests that Convair’s TASSEL work fed directly into its MTSS proposal.
Not the prettiest ruby, for sure. (Credit: Gems of Science, YouTube)
Sapphires and rubies aren’t just pretty, they also got a range of practical uses. This makes it even more useful to be able to make them at home for obviously completely innocent experiments. Cue [Gems of Science] and his attempts to make good-looking rubies, without resorting to the brute-force laser blasting approach that [Styropyro] previously used to create murky-looking gems.
That basic method used involves blasting aluminium oxide with a laser, which results in a container full of what are technically gems, but – as the image on the right makes clear – not exactly the prettiest or easiest to shine up. Much of the problem here is that these are hollow geodes composed of countless tiny crystals instead of solid singular crystals.
Although there are commercial ways to fairly easily create large crystals from a small seed crystal, none of these lend themselves to a DIY hobbyist with just a garage to muck about in. This leaves one alternative: the flux method. Rather than melting the material that will be grown onto the seed crystal, this flux crystal growth method uses a solvent (flux) and temperatures that a home kiln can achieve.
These rubies may be small, but are very shiny. (Credit: Gems of Science, YouTube)
Of note here is also that it’s the addition of Cr3+ ions into the base Al2O3 matrix that makes a ruby into a ruby, by giving it its red glow. In order to grow crystals this way you need to pick not only a suitable solvent, but also use a crucible that doesn’t want to become part of said crystal. Unfortunately a platinum crucible runs into the thousands of USD, but a graphite crucible should do if you keep oxygen away from it.
For the flux molybdenum oxide was used, mixed with chromium oxide and aluminium oxide to provide the ingredients for crystal growth. Unfortunately added charcoal interfered with the molybdenum, ruining that batch. This led to trying out more crucible types to find a recipe that worked, thereby finding out that an ‘alumina’ crucible also contained silica, which poisons the reaction, resulting in only tiny ruby crystals.
Ultimately pure alumina crucibles seemed to work great, until they began to shatter en masse, resulting in pained wallet noises and the purchases of some pre-loved platinum crucibles. This worked really well, but now the flux was evaporating too quickly to enable large crystal growth, thus requiring additives to stabilize it. Along with temperature cycling to induce the growth of larger crystals, this finally generated some solid results. After a first batch of smaller rubies, next up larger ones of up to 10 mm were grown.
While cutting one of these large rubies to set into a ring it was clear that it was still rather flawed, with pockets of flux captured into the crystal, but with the basic method now more or less dialed in it should be possible to address these small flaws as well.
The Casio F-91W digital watch is perhaps one of the most successful pieces of consumer electronics ever made, having quietly supplied the essential function of an inexpensive and accurate LCD digital timepiece for many decades. As a result it has a huge following, and we’ve seen plenty of projects based upon it. [Matteo P] has one that we think you’ll like, he’s turned his Casio into a contactless payment device. We missed it when it came out, but sometimes a good project needs sharing.
If you’re a long-time Hackaday reader you may remember our investigation of 13.56 MHz NFC cards in which we showed you a disassembled card in which he antenna was a tuned circuit covering most of the card, with a small coupling coil for the chip. It’s this kind of card he uses, and ends up with an SLA printed front face for the watch that places the chip above the display and puts a pick-up coil around the outside. The most interesting part of the write-up though isn’t in the build, instead it’s the deep-dive into designing the RF parts and ensuring a good coupling at something close to resonance. Read it, if you fancy trying NFC-enabling any other random items.
