If you don’t own a cat, hearing the sound of one meowing from somewhere in the house probably comes as quite a shock. The Cat Prank box built by [Reuben] promises to deliver such hilarity with aplomb.
The idea is simple: hide the Cat Prank box in a cupboard or other space in a friend’s house, and it will meow from its secret location. When found, either the light sensor or motion sensor will trigger the yowling of an angry feline, with hopefully startling effects.
An Arduino Mini is the brains of the operation, paired with an XY-V17B sound module which plays the required animal wailings. There’s also a 433 MHz radio module that lets the prankster trigger meowing via remote control.
Code is available for those wishing to build their own. We’d love to see a mod with a time delay built in, so the device could be hidden and left to start meowing at some later date when the prankster is far away.
Similar work has graced these pages before, like the devilishly fiendish OpenKobold design. Just make sure your friends are receptive to such jokes before you go ahead and invest time and hardware in the prank!
Over on Retro Recipe’s YouTube channel, [Perifractic] has been busy restoring an old promotional video of how Commodore computers were made back in 1984 (video below the break). He cleaned up the old VHS-quality version that’s been around for years, translated the German to English, and trimmed some bits here and there. The result is a fascinating look into the MOS factory, Commodore’s German factory, and a few other facilities around the globe. The film shows the chip design engineers in action, wafer manufacturing, chip dicing, and some serious micro-probing of bare die. We also see PCB production, and final assembly, test and burn-in of Commodore PET and C64s in Germany.
Check out the video description, where [Perifractic] goes over the processes he used to clean up video and audio using machine learning. If restoration interests you, check out the piece we wrote about these techniques to restore old photographs last year. Are there any similar factory tour films, restored or not, lurking around the web? Let us know in the comments below.
Continue reading “Commodore Promotional Film From 1984 Enhanced” →
Those readers who have experimented with winding their own inductors will know that it’s not an easy task, and when those inductors are handling high voltages it can be especially tricky to maintain adequate insulation between layers of windings. [Open Frime TV] has a video addressing this in a novel way, by creating the windings for a switch-mode power supply transformer using stacked PCB coils instead of wire (Russian language; you’ll have to enable YouTube’s subtitle auto-translation).
The video below the break makes for a handy primer on PCB coil construction, reminding the viewer that the turns need all to lie in the same direction as well as the importance of insulation between windings. There’s a discussion of the properties of a PCB coil in relation to the switching frequency, and once the transformer has been assembled, we see it hooked up to a power supply board for a test. What happens next may be familiar to seasoned transformer-winders; nothing works, and the transformer gets hot. In making the PCB he’s left some copper on each board which amounts to a shorted turn — cutting these allows the transformer to work perfectly.
This technique might not be the solution to all transformer woes, but makes for an interesting option if your work takes you in the direction of winding transformers. If PCB coils take your interest, how about a Tesla coil using them?
Continue reading “Planar PCB Coils As An Alternative To Winding Transformers” →
Seems like all the cool kids are rewriting legacy C programs in Rust these days, so we suppose it was only a matter of time before somebody decided to combine the memory-safe language with some of the most historically significant software ever written by way of a new Apollo Guidance Computer (AGC) emulator. Written by [Felipe], the Apache/MIT licensed emulator can run either ROM files made from the computer’s original rope core memory, or your own code written in AGC4 assembly language.
It’s worth noting that the emulator, called
ragc, needs a bit of help before it can deliver that authentic Moon landing experience. Specifically, the code only emulates the AGC itself and stops short of recreating the iconic display and keyboard (DSKY) module. To interact with the programs running on the virtual AGC you’ll need to also install yaDSKY2, an open source project that graphically recreates the panel Apollo astronauts actually used to enter commands and get data from the computer.
Of course, the next step would be to hack in support for talking to one of the physical recreations of the DSKY that have graced these pages over the years. Given the limitations of the AGC, we’d stop short of calling such an arrangement useful, but it would certainly make for a great conversation starter at the hackerspace.
Thanks for the tip, [CJ].
Looking to get into fault injection for your reverse engineering projects, but don’t have the cash to lay out for the necessary hardware? Fear not, for the tools to glitch a chip may be as close as the nearest barbecue grill.
If you don’t know what chip glitching is, perhaps a primer is in order. Glitching, more formally known as electromagnetic fault injection (EMFI), or simply fault injection, is a technique that uses a pulse of electromagnetic energy to induce a fault in a running microcontroller or microprocessor. If the pulse occurs at just the right time, it may force the processor to skip an instruction, leaving the system in a potentially exploitable state.
EMFI tools are commercially available — we even recently featured a kit to build your own — but [rqu]’s homebrew version is decidedly simpler and cheaper than just about anything else. It consists of a piezoelectric gas grill igniter, a little bit of enameled magnet wire, and half of a small toroidal ferrite core. The core fragment gets a few turns of wire, which then gets soldered to the terminals on the igniter. Pressing the button generates a high-voltage pulse, which gets turned into an electromagnetic pulse by the coil. There’s a video of the tool in use in the Twitter thread, showing it easily glitching a PIC running a simple loop program.
To be sure, a tool as simple as this won’t do the trick in every situation, but it’s a cheap way to start exploring the potential of fault injection.
Thanks to [Jonas] for the tip.
The really nice thing about doing something the “wrong” way is that there’s just so much variety! If you’re doing something the right way, the fastest way, or the optimal way, well, there’s just one way. But if you’re going to do it wrong, you’ve got a lot more design room.
Case in point: esoteric programming languages. The variety is stunning. There are languages intended to be unreadable, or to sound like Shakespearean sonnets, or cooking recipes, or hair-rock ballads. Some of the earliest esoteric languages were just jokes: compilations of all of the hassles of “real” programming languages of the time, but yet made to function. Some represent instructions as a grid of colored pixels. Some represent the code in a fashion that’s tantamount to encryption, and the only way to program them is by brute forcing the code space. Others, including the notorious Brainf*ck are actually not half as bad as their rap — it’s a very direct implementation of a Turing machine.
So you have a set of languages that are designed to be maximally unlike each other, or traditional programming languages, and yet still be able to do the work of instructing a computer to do what you want. And if you squint your eyes just right, and look at as many of them all together as you can, what emerges out of this blobby intersection of oddball languages is the essence of computing. Each language tries to be as wrong as possible, so what they have in common can only be the unavoidable core of coding.
While it might be interesting to compare an contrast Java and C++, or Python, nearly every serious programming language has so much in common that it’s just not as instructive. They are all doing it mostly right, and that means that they’re mostly about the human factors. Yawn. To really figure out what’s fundamental to computing, you have to get it wrong.
The quality of consumer-grade 3D printing has gone way up in recent years. Resin printers, in particular, can produce amazing results and they get less expensive every day. [Squidmar] took a miniature design and printed it (or had it printed) on some cheap resin printers and a 65,000 Euro DWS029. How much difference could there be? You can see for yourself in the video below.
We were surprised at the specs for the more expensive machine. It does use a solid-state laser, but for that cost, the build volume is relatively small — around 15 x 15 x 10 cm. There were actually five prints created on four printers. Three were on what we think of as normal printers, one was on the 65,000 Euro machine, and the fifth print was on a 10,000 Euro printer that didn’t look much different from the less expensive ones.
Of course, there is more to the process than just the printer. The resin you use also impacts the final object. The printers tested included a Phrozen 4K Mini, a Phrozen 8K Mini, a Solos Pro, and the DWS 029D. The exact resins or materials used was hard to tell in each case, so that may have something to do with the comparisons, too.
Do you get what you pay for? Hard to say. The 8K and Solos were neck-and-neck with some features better on one printer and some better on the other. The DWS029D did perform better, but was it really worth the increase in price? Guess it depends on your sensitivity. The 8K printer did a very credible job for a fraction of the cost. Of course, some of that could have been a result of the materials used, too, but it does seem likely that a very expensive dental printer ought to do better than a hobby-grade machine. But it doesn’t seem to do much better.
The DWS printer uses a laser, while most hobby printers use UV light with an LCD mask. We’ve seen low-end resin printers on closeout for around $100 and you can get something pretty nice in the $200 neighborhood. In between these two extremes are printers that use Digital Light Processing (DLP).
Continue reading “3D Printer Showdown: $350 Consumer Vs $73,000 Pro Machine” →