45 Minute Podcast Served Up On A Floppy Disk

Near the turn of the millenium, portable media players like the iPod led to the development of the podcast. The format generally consists of content similar to talk-based radio, and is typically served up in modern codecs like AAC, M4A and MP3. However, [Sean Haas] decided these were all too chunky, and wanted to see if it was possible to deliver similar content on a floppy disk. The results are predictable, but impressive.

[Sean]’s aim was to try and fit roughly 45 minutes of audio on to a 1.44 MB floppy disk. To pull this off, he looked far and wide for a codec fitting for the task. The choice landed on was Adaptive Multi-Rate, or AMR. Typically used to encode audio for GSM phone calls, it can also be used to create compressed audio files.

Initial attempts weren’t quite good enough to do the job, so [Sean] introduced a pre-processing step with FFMPEG, to speed the audio up 1.2 times. It was then passed through SoX and encoded in AMR at approximately 5 kbit/s. This allowed a 45-minute long MP3 file of 72MB to be compressed down into just 1.2 MB, and thus able to fit onto a floppy disk. Audio quality is predictably poor, as you can hear in the embedded clip below, but definitely intelligible. You’d probably want to skip any musical passages if you were doing this seriously.

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Talking Head Teaches Laplace Transform

Most people who deal with electronics have heard of the Fourier transform. That mathematical process makes it possible for computers to analyze sound, video, and it also offers critical math insights for tasks ranging from pattern matching to frequency synthesis. The Laplace transform is less familiar, even though it is a generalization of the Fourier transform. [Steve Bruntun] has a good explanation of the math behind the Laplace transform in a recent video that you can see below.

There are many applications for the Laplace transform, including transforming types of differential equations. This comes up often in electronics where you have time-varying components like inductors and capacitors. Instead of having to solve a differential equation, you can perform a Laplace, solve using common algebra, and then do a reverse transform to get the right answer. This is similar to how logarithms can take a harder problem — multiplication — and change it into a simpler addition problem, but on a much larger scale.

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Hackaday Links: August 9, 2020

We regret to admit this, but we completely missed the fact that Windows 10 turned five years old back in March. Granted, things were a little weird back then — at least it seemed weird at the time; from the current perspective, things were downright normal then. Regardless, our belated congratulations to Microsoft, who, like anyone looking after a five-year-old, spends most of their time trying to keep their charge from accidentally killing itself. Microsoft has done such a good job at keeping Windows 10 alive that it has been installed on “one billion monthly active devices”. Of course, back in April of 2015 they predicted that the gigainstall mark would be reached in 2018. But what’s a couple of years between friends?

Of all the things that proved to be in short supply during the pandemic lockdowns, what surprised us most was not the toilet paper crunch. No, what really surprised us was the ongoing webcam supply pinch. Sure, it makes sense, with everyone suddenly working from home and in need of a decent camera for video conferencing. But we had no idea that the market was so dominated by one manufacturer — Logitech — that their cameras could suddenly become unobtainium. Whatever it is that’s driving the shortage, we’d take Logitech’s statement that “demand will be met in the next 4-6 weeks” with a huge grain of salt. After all, back-to-school shopping is likely to look vastly different this year than in previous years.

Speaking of education, check out the CrowPi2 STEM laptop. On the one hand, it looks like just another Raspberry Pi-based laptop, albeit one with a better level of fit and finish than most homebrew Pi-tops. With a Raspberry Pi 4b on board, it can do all the usual stuff — email, browse the web, watch videos. The secret sauce is under the removable wireless keyboard, though: a pretty comprehensive electronics learning lab. It reminds us of the Radio Shack “150-in-One” kits that so many of us cut our teeth on, but on steroids. Having a complete suite of modules and a breadboarding area built right into the laptop needed to program it is brilliant, and we look forward to seeing how the Kickstarter for this does.

Exciting news from Hackaday Superfriend Chris Gammell — he has launched a new podcast to go along with his Contextual Electronics training courses. Unsurprisingly dubbed the Contextual Electronics Podcast, he already has three episodes in the can. They’re available as both video and straight audio, and from the few minutes we’ve had to spend on them so far, Chris has done a great job in terms of production values and guests with Sophy Wong, Stephen Hawes, and Erik Larson leading off the series. We wish him luck with this new venture, and we’re looking forward to future episodes.

One of the best things about GoPro and similar sports cameras is their ability to go just about anywhere and show things we normally don’t get to see. We’re thinking of those gorgeous slo-mo selfies of surfers inside a curling wave, or those cool shots of a skier powder blasting down a mountain slope. But this is the first time we’ve seen a GoPro mounted inside a car’s tire. The video by the aptly named YouTuber [Warped Perception] shows how he removed the tire from the wheel and mounted the camera, a battery pack, and an LED light in the rim, then remounted the tire. The footage of the tire deforming as it contacts the ground is fascinating but oddly creepy. It sort of reminds us a little of the footage from cameras inside the Saturn V fuel tanks — valuable engineering information to be sure, but forbidden in some way.

How About A Nice Cuppa TEA Laser?

If lasers are your hobby, you face a conundrum. There are so many off-the-shelf lasers that use so many different ways of amplifying and stimulating light that the whole thing can be downright — unstimulating. Keeping things fresh therefore requires rolling your own lasers, and these DIY nitrogen TEA and dye lasers seem like a fun way to go.

These devices are the work of [Les Wright], who takes us on a somewhat lengthy but really informative tour of transversely excited atmospheric (TEA) lasers. The idea with TEA lasers is that a gas, often carbon dioxide in commercial lasers but either air or pure nitrogen in this case, is excited by a high-voltage discharge across long parallel electrodes. TEA lasers are dead easy to make — we’ve covered them a few times — but as [Les] points out, that ease of construction leads to designs that are more ad hoc than engineered.

In the video below, [Les] presents three designs that are far more robust than the typical TEA laser. His lasers use capacitors made from aluminum foil with polyethylene sheets for dielectric, sometimes with the addition of beautiful “doorknob” ceramic caps too. A spark gap serves as a very fast switch to discharge high voltage across the laser channel, formed by two closely spaced aluminum hex bars. Both the spark gap and the laser channel can be filled with low-pressure nitrogen. [Les] demonstrates the power and the speed of his lasers, which can even excite laser emissions in a plain cuvette of rhodamine dye — no mirrors needed! Although eye protection is, of course.

These TEA lasers honestly look like a ton of fun to build and play with. You might not be laser welding or levitating stuff with them, but that’s hardly the point.

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Hands-On: Internet Of Batteries Quantum Badge Brings Badgelife Add-Ons The Power And Internet They Crave

Our friends in the Whiskey Pirates crew sent me the unofficial DEF CON badge they built this year. The Internet of Batteries QUANTUM provides power and connectivity to the all-important add-on badges of DC28. The front of the badge is absolutely gorgeous to the point I don’t really want to solder on my add-on headers and disrupt that aesthetic.

The gold-plated copper makes for a uniformed and reflective contrast to the red solder mask which occupies the majority of the front. Here we see the great attention to detail that [TrueControl] includes in his badges. The white stripe of silk screen separating the two colors is covered by some black detailing tape that looks much better than the white.

The antenna of the ESP32 module poking out the underside of the gold cover end of the badge gets its own rectangle of the holographic sticker material, the same as the sheet of stickers that was included in the box. Both decals are small details that make a huge difference to your eye.

The line of nine RGB LEDs have black bezels which goes along with the black stripe motif and underscores the typography of the badge name. These lights are hosted on a daughter board soldered to the underside of the badge with a slot for the LEDs to pass through. They are addressed in a 2×15 matrix that is scanned on the low side by the PSoC5 that drives the badge. This low-res image shows that daughter board before the lithium cell is placed.

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Recreating Early Apple Mice For The Modern Era

At a time when practical graphical user interfaces were only just becoming a reality on desktop computers, Apple took a leap of faith and released one of the first commercially available mice back in 1983. It was criticized as being little more than a toy back then, but we all know how that particular story ends.

While the Apple G5431 isn’t that first mouse, it’s not too far removed. So much so that [Stephen Arsenault] believed it was worthy of historic preservation. Whether you want to print out a new case to replace a damaged original or try your hand at updating the classic design with modern electronics, his CAD model of this early computer peripheral is available under the Creative Commons license for anyone who wants it.

The model is exceptionally well detailed.

[Stephen] tells us that he was inspired to take on this project after he saw new manufactured cases for the G5431 popping up online, including a variant made out of translucent plastic. Realizing that a product from 1986 is old enough that Apple (probably) isn’t worried about people cloning it, he set out to produce this definitive digital version of the original case components for community use.

With these 3D models available, [Stephen] hopes that others will be inspired to try and modify the iconic design of the G5431. Perhaps by creating a Bluetooth version, or adding the ability to right-click. Considering we’ve already seen custom PCBs for mice, it’s hardly a stretch. We’d love to see somebody take him up on the offer, but even if not, the digital preservation of computer history is always welcome.

OAK Vision Modules Help You See The Forest And The Trees

OpenCV is an open source library of computer vision algorithms, its power and flexibility made many machine vision projects possible. But even with code highly optimized for maximum performance, we always wish for more. Which is why our ears perk up whenever we hear about a hardware accelerated vision module, and the latest buzz is coming out of the OpenCV AI Kit (OAK) Kickstarter campaign.

There are two vision modules launched with this campaign. The OAK-1 with a single color camera for two dimensional vision applications, and the OAK-D which adds stereo cameras for that third dimension. The onboard brain is a Movidius Myriad X processor which, according to team members who have dug through its datasheet, have been massively underutilized in other products. They believe OAK modules will help the chip fulfill its potential for vision applications, delivering high performance while consuming low power in a small form factor. Reading over the spec sheet, we think it’s fair to call these “Ultimate Myriad X Dev Boards” but we must concede “OpenCV AI Kit” sounds better. It does not provide hardware acceleration for the entire OpenCV library (likely an impossible task) but it does cover the highly demanding subset suitable for Myriad X acceleration.

Since the campaign launched a few weeks ago, some additional information have been released to help assure backers that this project has real substance. It turns out OAK is an evolution of a project we’ve covered almost exactly one year ago that became a real product DepthAI, so at least this is not their first rodeo. It is also encouraging that their invitation to the open hardware community has already borne fruit. Check out this thread discussing OAK for robot vision, where a question was met with an honest “we don’t have expertise there” from the OAK team, but then ArduCam pitched in with their camera module experience to help.

We wish them success for their planned December 2020 delivery. They have already far surpassed their funding goals, they’ve shipped hardware before, and we see a good start to a development community. We look forward to the OAK-1 and OAK-D joining the ranks of other hacking friendly vision modules like OpenMV, JeVois, StereoPi, and AIY Vision.