Hearing The Unhearable

August 7, 2021 by Elliot Williams 51 Comments

My wife was watching a crime drama, and one of the plot twists involved a witness’ hearing aid malfunctioning so that he could hear electromagnetic waves around him. It’s not so implausible, if you think about it. Many hearing aids have a t-coil, which is essentially an inductor that’s designed to couple with the speaker in a telephone. If that went haywire, maybe you could hear all the changing magnetic fields around you, and if you could escape the constant hum of the mains power line, it might even be interesting.

So of course, she turns to me and says “we need to make one!” It shouldn’t be hard at all — a big inductor and an amplifier should do the trick. In fact, it’ll probably be easy enough that it’ll make a good introduction-to-electronics project for my son. But there are also enough unknowns here that it’ll be interesting. How big a coil? How close? How sensitive? What about that mains frequency bit? Ferrite core or not?

None of this is rocket science, for sure, but it will probably be full of kludges, discoveries, and straight-up exploration. In short, the perfect weekend project. And in the end, it’ll expose something that’s normally invisible, and that’s where the fun lies.

This must be the same urge that drove Faraday and Marconi, Volta and Maxwell. There’s something amazing about directly sensing, seeing, hearing, and understanding some of the stuff that’s outside of our limited hearing and eyesight, and yet is all around us. I can write down the equations that describe it — I learned them in school after all — but there’s no substitute for poking around in your own home. Who knows, maybe in a few more weekends we’ll build ourselves an all-band receiver.

What’s your favorite super power?

Capstan Drive Is Pulling The Strings On This Dynamic Quadruped

August 7, 2021 by Sonya Vasquez 8 Comments

When it comes to legged robots, it’s easy to think that the complexity and machining costs would keep these creatures far away from becoming anyone’s garage hobby. But, through a series of clever design choices, [Damian Lickindorf] has found a way to beat the odds and give life to Stanley, a low-cost, dynamic quadruped with some serious kick!

As if building a working legged robot weren’t already a tricky task, [Damian] has made some classy design choices to keep the price low and reduce fabrication complexity without sacrificing performance. Keeping up with the latest trend in Quasi-Direct Drive legged robots that started with the MIT Mini Cheetah, [Damian] constructed a small transmission with a gear reduction under 1:9. This choice slightly reduces the amount of heat produced by operating the motor at low-speeds with high torque without sacrificing too much control bandwidth (think: “leg responsiveness”).

Unlike the Cheetah, though, which uses a planetary gearbox, [Damian] opts for a capstan drive, a cable-driven transmission that’s both backlash free and backdriveable: two must-haves for force-sensitive dynamic legged robots. For legs, he’s opting for 2d machined FR4 (think: circuit board material). And for motors, he’s chosen a set of brushless motors with a large gap radius and driven by Moteus Drivers. The result is high fidelity, dynamic build that’s a fraction of the cost of some of the creatures we’re seeing emerge from academic research labs.

If you’re looking to feast your eyes on some action shots, look no further than [Damian’s] YouTube and Instagram presence. And if you’re looking to follow the project, have a look at the Hackaday.io project. While we’re eager to see the project continue to unfold, we’re thrilled by how far it’s come. In the meantime, be sure to take a look at one of the project’s inspirations: the Mjbots Quad A0.

Finally, since we’ve not seen capstan drives much on Hackaday, if you’re curious about these mechanisms and can get past the paywall, these two research papers might be a good place to dig deeper.

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Everything You Always Wanted To Know About Radioactive Lenses

August 7, 2021 by Al Williams 45 Comments

We think of radioactive material as something buried away in bunkers with bombs, power plants, and maybe some exotic medical equipment. But turns out, there are little bits of radiation in the water, our soil, bananas, granite countertops, smoke detectors, and even some camera lenses. Camera lenses? A few decades ago, camera companies added rare elements like thorium to their glass to change the optical properties in desirable ways. The downside? Well, it made the lenses somewhat radioactive. A post by [lenslegend] explains it all.

Exotic elements such as Thorium, Lanthanum and Zirconium are added to glass mixtures to create the high refractive indexes necessary in sophisticated lens designs. Selection of premium quantities of glass from the large glass pots, stringent spectrophotometric tests after stress and strain checks provide the valuable raw glass for ultimate use in lens elements.
—Konica Hexanon Lens Guide, Konica Camera Company, 1972

According to [lenslegend] the practice started in 1945 with Kodak. However, by the 1980s, consumer distaste for radioactive things and concern for factory workers ended the production of hot camera lenses.

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Game Boy Color Makes Itself At Home In A DMG-01

August 6, 2021 by Tom Nardi 2 Comments

When we last checked in with [Bucket Mouse], he had just finished cramming a Game Boy Advance (GBA) SP motherboard into the body of the iconic Game Boy DMG-01, complete with an aftermarket IPS display. Unfortunately, after a few weeks of using the system, he ran into a few issues that sent him back to the drawing board.

This time, he’s revamped Nintendo’s classic handheld with the internals from its successor, the Game Boy Color (GBC). Obviously that means this new build can’t play any GBA titles, but that was never actually the goal in the first place. It might seem obvious in hindsight, but owing to their general similarity, it ended up being far easier to fit the GBC hardware into the Game Boy’s shell. Though we still wouldn’t call this an “easy” swap by any stretch of the imagination…

Whether you want to follow his footsteps towards portable gaming bliss or just want to live vicariously through his soldering iron, [Bucket Mouse] has done an absolutely phenomenal job of documenting this build. While he cautions the write-up isn’t designed to be a step by step instructional piece, there’s an incredible wealth of information here for others looking to perform similar modifications.

The build involved removing much of the original Game Boy’s connectors and controls, such as the volume wheel, Link Port, and even headphone jack, and grafting them onto a GBC motherboard that’s been physically trimmed down. At a high level it’s not unlike the trimmed Wii portables we’ve seen, but made much easier due to the fact the GBC only used a two-layer PCB. It also helps that [Bucket Mouse] has once again used an aftermarket IPS display, as that meant he could literally cut off the LCD driver section of the GBC motherboard. Of course there have also been several hardware additions, such as a new audio amplifier, power regulation system, LiPo charger, and 2000 mAh battery.

There’s a lot of fantastic details on this one, so if you’re remotely interested in what made the Game Boy and its successors tick, we’d highly recommend taking the time to read through this handheld hacking tour de force. His previous build is also more than worthy of some close study, even if it ended up being a bit ungainly in practice.

Retro Computers From Paper

August 6, 2021 by Chris Lott 22 Comments

Want to start your own collection of retro computers, for free? Well graphic designer [Rocky Bergen]’s collection of paper craft models might be the answer. [Rocky] has designed over a dozen models of old computers, including classics such as the IMSAI 8080, Commodore Pet, and the BBC Microcomputer to name just a few.

The completed size of these models isn’t mentioned, but inspecting the PDF file of a randomly selected Commodore C64 model shows it was intended to be printed on A3 paper ( 297 x 420 mm, or roughly the size of an 11 x 17 ANSI C page if you think better in inches ). That still doesn’t give us the finished size of a model, but one collector posted on [Rocky]’s site that when he scaled it to A4 paper, the resulting computer was a perfect match for use with common 1/6 scale dolls and dollhouses (also known as playscale). Of course, the pattern existing as a computer PDF file, you can scale it to any size you want.

We’ve covered a few paper craft projects in the past, including these cool automata, a claw from a crane game, and even a gyroscope that really spins. Check out the video below the break to see [Rocky] assembling the Apple II paper craft model. Thanks to [CollegeCop] for sending this into our tip line.

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Pen Plotter Is About As Simple As It Can Get

August 6, 2021 by Al Williams 14 Comments

Sure, we see quite a few plotters and other motion machines, but the one from [DAZ Projects] has the virtual of looking dead simple. The Arduino and CNC shield are old hat, of course. But some 3D printed pulleys and a very simple-looking core XY arrangement looks like this could be a pretty quick build.

You might ask; if you have a 3D printer, why you wouldn’t just mount a pen on it and call it a day? Well, you could do that, of course, but what fun is that? Besides, that will tie up your printer, too. You can see a video of the project, below.

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Cool Binary Clock Uses Old-School LEDs And A Fancy Graphic PCB

August 6, 2021 by Lewin Day 21 Comments

Ah, the 5mm LED. Once a popular choice, they’ve been supplanted in modernity by smaller SMD components and/or more capable RGB parts in recent years. However, they’re still able to do the job and are a great way to give your project that proper homebrew look. [Ian Dunn] chose those very parts to produce his 4017 Decade Binary Clock.

The clock uses only digital logic ICs to tell the time – there are no microcontrollers here! After four or five iterations over almost a whole year, [Ian] was finally able to coax the circuit into reliable operation. As you’d expect, it relies on a 32.768 kHz crystal to provide a stable clock. Fed into a 4060 binary ripple counter, that clock is divided down 14 times to deliver a 2Hz square wave. This then goes through a 4027 flip flop to get the desired 1Hz signal. From there, a bunch of extra logic handles counting the seconds, minutes, and hours, and resetting the counters as appropriate.

The PCB that houses the project is printed on directly by a flatbed inkjet printer, which [Ian] purchased when inspired by our previous article on how to get your PCBs made at the mall. He didn’t actually use it to make the PCB in this case, but the flatbed printer does a great job of putting graphics on the board.

The result is quite an attractive look that might surprise a few electronics enthusiasts who haven’t seen a graphic printed board before. It’s a technique we think could be used to great effect on conference badges, too. If you’ve experimented with similar techniques, be sure to drop us a line!