Droplet Watch Keeps Time Via Electrowetting

Hackers just can’t help but turn their sights on timepieces, and [Armin Bindzus] has designed an electrowetting-based watch.

Electrowetting is a way of changing the contact angle of droplets on a surface using electricity, and can be used to move said droplets. The liquid needs to be polar, so in this case [Bindzus] has used a red ink mixed with mono-ethylene glycol to stand out against the white dielectric back of the device. The 60 individual electrodes of the bottom section were etched via laser out of the ITO-coated glass that makes up the bottom plates of the face.

The top plate houses the small round pillars that keep the ink constrained to its paths. They are made of a photosensitive epoxy that is spin-coated onto the glass and then cured via the laser. The plates are put together at a distance of 0.23 mm with epoxy, but a small hole is left to insert the droplets and a filler liquid. An Attiny1614 microcontroller runs the show along with a DS3231 RTC. A 46V signal drives the droplets around their path.

It seems this project is a bit away from true wearable use, but perhaps [Bindzus] could make a desk clock first? If you’re interested in another ink-based, watch, how about this custom E-Ink Tank watch?

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Breaking Through The 1 MB Barrier In DOS With Unreal Mode And More

The memory map of the original 8086 computer with its base and extended memory made the original PC rather straightforward, but also posed countless issues for DOS-based applications as they tried to make use of memory beyond the legacy 1 MB address space. The initial ways to deal with this like EMS, XMS and UMB were rather cumbersome and often impractical, but with the arrival of the 80286 and 80386 processors more options opened up, including protected mode. More interestingly, this led to unreal mode, DOS extenders and the somewhat more obscure LOADALL instruction, as covered by [Julio Merino] in a new article.

This article builds on the first one which covered the older methods and covered the basics of protected mode. Where protected mode is convenient compared to real mode is that with the former the memory accesses go via the MMU and thus allows for access to 16 MB on the 80286 and 4 GB on the 80386. The segment descriptors and resolving of these that make this possible can be (ab)used on the 80286 and up by realizing that these segment descriptors are also used in real mode. Unreal mode is thus about switching to protected mode, loading arbitrary segment descriptors and switching back to real mode. As this is outside the original processor spec, it is commonly called ‘unreal mode’.

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20,000 Volt Plasma Knife Slices, Dices, And Sparks

For the most part, here at Hackaday we’re more interested in how something was made than the backstory on why an individual actually put it together. Frankly, it’s not really our business. But we’ve been around long enough to know that practicality isn’t always the driving force. Some folks build things because they want to challenge themselves, others because there’s nothing commercially available that quite meets their needs. Of course, there’s another camp that just builds things to look cool.

In the case of the plasma-infused blade [Jay Bowles] recently put together for Plasma Channel, we imagine it was a bit from each column. The basic inspiration was to create something in the style of the “Energy Sword” from Halo, but the resulting electrified blade is no mere prop. Inside the 3D printed enclosure, it packs not only the electronics necessary to produce 20,000 volts from the built-in battery pack, but a fan to help push the resulting plasma down the length of the two-piece steel blade.

As you might expect, it took a few attempts to get there. In the video after the break, [Jay] shows off the design process and some earlier incarnations of the plasma knife that didn’t quite live up to expectations. While there were always some impressive sparks, the spacing of the blades and the output power of the miniature high-voltage generator both needed fine tuning before it resulted in the band of plasma he was aiming for.

Is there a practical use for such a thing? Well the spark between the blades can apparently be used to light stuff on fire, and of course, you can cut things with it. But realistically…no, not really. It just looks cool, which is fine by us.

Should you prefer your high-voltage experimentation to have a more clearly defined goal, you might be interested in the ongoing work [Jay] has been doing with ionic propulsion and magnetohydrodynamic drives (MHDs).

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Keeping Track Of The Night Sky With Discrete Logic Chips

As hobbies go, stargazing has a pretty low barrier to entry. All you really need is a pair of Mark 1 eyeballs and maybe a little caffeine to help you stay up late enough. Astronomy, on the other hand, takes quite a bit more equipment, not least of which is a telescope and a way to get it pointed in the right direction at the right time, and to make up for the pesky fact that we’re on a moving, spinning ball of rock.

Yes, most of the equipment needed for real astronomy is commercially available, but [Mitsuru Yamada] decided to go his own way with this homebrew retro-style telescope motor controller. Dubbed MCT-6, the controller teams up with his dual-6502 PERSEUS-9 computer to keep his scope on target. There are a lot of literally moving parts to this build, including the equatorial mount which is made from machined aluminum and powered by a pair of off-the-shelf stepper-powered rotary stages for declination and right ascension. The controller that runs the motors is built completely from discrete 74HCxx logic chips that divide down a 7.0097-MHz crystal oscillator signal to drive the steppers precisely at one revolution per diurnal day. The pulse stream can also be sped up for rapid slewing, to aim the telescope at new targets using a hand controller.

As impressive as all this is, the real star (sorry) of the show here is the fit and finish. In typical [Yamada-san] fashion, the impeccably wire-wrapped mainboard fits in a robust die-cast aluminum case that fits the retro aesthetic of the whole project. The PERSEUS-9 is used mainly as a display and control terminal, running custom software to show where the telescope is pointed and calculate the coordinates of various heavenly bodies. As a bonus, the 40×7 alphanumeric red LED display should be easy on dark-adapted eyes.

Hats off to [Mitsuru Yamada] on another fabulous build. If you haven’t had enough of his build style yet, be sure to check out his PERSEUS-8 or even his foray into the analog world.

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FOSDEM Saved, With 3D Printing

If you were to consider what the most important component of a hacker event might be, the chances are you’d pick something that’s part of the program, the ambiance, or the culture. But as the organizers of FOSDEM in Brussels found out, what’s really the most important part of such an event is the toilet paper.

If you can’t keep the supplies coming, you’re in trouble, and since they only had one key for the dispensers across the whole event, they were heading for a sticky situation. But this is a hacker event, and our community is resourceful. The folks on the FreeCAD booth created a model of the key which they shared via the Ondsel collaboration tools, while those on the Prusa booth fired up their Prusa XL and ran off a set of keys to keep the event well supplied.

Perhaps for many of us, the act of running off a 3D model and printing it is such a mundane task as to be unremarkable — and indeed the speed at which they were able to do it points to it being a straightforward task for them. But the sight of a bunch of hardware hackers saving the event by doing what they do best is still one to warm the cockles of our hearts. We’re fairly certain it’s not the first time we’ve seen a bit of clandestine venue hacking save an event, but perhaps for the sake of those involved, we’d better not go into it.

Better Living Through Biomedical Engineering

We don’t often think of medicine and engineering as being related concepts, and most of the time, they aren’t. But there’s a point where medicine alone may not be enough to treat a particular ailment or injury, and it might be necessary to blend the mechanical with the biological. When a limb is lost, we don’t have the technology to regrow it, but we can apply engineering principles to build a functional facsimile that can help the patient regain lost independence and improve their quality of life.

The area where these two disciplines overlap is called biomedical engineering (BME), and it’s a field that’s seeing fantastic growth thanks to advances in 3D printing, materials science, and machine learning. It’s also a field where open source principles and DIY are making surprising inroads, as hobbyists look to put their own knowledge and experience to use by creating low-cost assistive devices — something we were honored to help facilitate over the years through the Hackaday Prize.

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Hackaday Podcast Episode 256: 0, 256, 400, 0x100, And 10000000

For this week’s episode, we did something super special — we all convened to answer your burning questions about your hosts, both as hackers and as humans. We kick things off with a segment featuring a hearty round-table discussion between Elliot, Al, Dan, Kristina, and Tom. What’s on our benches? What do we type on? Go find out!

None of us figured out What’s That Sound though a few of us had some creative guesses. Can you guess the sound? There could be a t-shirt in it for ya.

Kristina and Elliot went on to have a normal podcast too, but since the round table section went so long, we’ll process up that section and put it out early next week.

Check out the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Download this epic monument of podcasting and savor it for the next 256 weeks.