One Project At A Time, Or A Dozen?

February 10, 2024 by Elliot Williams 34 Comments

We got a bunch of great food for thought in this week’s ask-us-anything on the Hackaday Podcast, and we all chewed happily. Some of my favorite answers came out of the question about how many projects we all take on at once. Without an exception, the answer was “many”. And while not every one of the projects that we currently have started will eventually reach the finish line, that’s entirely different from saying that none of them ever do. On the contrary, Tom Nardi made the case for having a number of irons simultaneously in the fire.

We all get stuck from time to time. That’s just the nature of the beast. The question is whether you knuckle down and try to brute-force power your way through the difficulty, or whether you work around it. A lot of the time, and this was Dan Maloney’s biggest bugaboo, you lack the particular part or component that you had in mind to get the job done. In that situation, sometimes you just have to wait. And what are you going to do while waiting? Work on Project B! (But take good notes of the state of Project A, because that makes it a lot easier to get back into the swing of things when the parts do arrive.)

Al and I both weighed in on the side of necessity, though. Sometimes, no matter how many attractive other projects you’ve got piled up, one just needs to get out the door first. My recent example was our coffee roaster. Before I start a big overhaul, I usually roast a couple days’ worth of the evil bean. And then the clock starts ticking. No roasting equals two unhappy adults in this household, so it’s really not an option. Time pressure like that helps focus the mind on the top-priority project.

But I’m also with Tom. It’s a tremendous luxury to have a handful of projects in process, and be able to hack on one simply because you’re inspired, or in love with the project at that moment. And when the muse calls, the parts arrive, or you finally figure out what was blocking you on Project A, then you can always get back to it.

Minitel, The 1980s Console Game Platform You Never Had

February 10, 2024 by Jenny List 14 Comments

We’ve made no secret over the years here at Hackaday of our admiration for the Minitel. The ubiquitous CRT terminals which made 1980s France the most connected country in the world never made it to where we grew up, but OH! how we wanted them to! We’ve seen quite a few Minitels repurposed as serial terminals here, but for the time being we think [Louis H] has won the Minitel Internet with his plugin game console cartridges. These have a DIN plug to fit the Minitel serial port, and present themselves as a serial game.

The cartridge itself is an extremely simple affair, a tube which fits over the DIN plug body, containing a slim PCB with an ATmega328 and its supporting components. The games must be programmed such that their gameplay can work over a serial interface, so as an example the first game is a version of 2048.

We applaud both the simplicity and creativity of this project, and we love it that a new 1980s console we never knew we had has been unearthed, without the need for hardware modification. Meanwhile if you’d like to peer inside an Alcatel Telic 1, we can take you there.

Simple Magnetic Levitator

February 10, 2024 by Al Williams 9 Comments

[Stoppi] always has exciting projects and, as you can see in the video below, the latest one is a very simple magnetic levitator design. The design is classic and simple: a 5 V regulator IC, a Hall effect sensor, a 741 op amp, and a MOSFET to turn the electromagnet on and off.

Sure, there are a few passive components and a diode, too, but nothing exotic. The sensor normally presents 2.5 V of output. The voltage rises or drops depending on the polarity of the magnetic field. The stronger the field, the more the voltage changes away from the 2.5 V center.

The op amp acts as a comparator with a potentiometer setting the trip point. As the ball moves up towards the coil, the voltage increases, triggering the comparator, which turns off the FET. With no current through the coil, there’s no more electromagnet, and the ball starts to fall.

Of course, as the ball falls, the voltage from the sensor also drops, and this eventually turns on the electromagnet. The ball eventually reaches a relatively stable position.

This is one of those cases where a simple analog circuit might work better than a digital one. Or make it hard on yourself and use an FPGA.

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Droplet Watch Keeps Time Via Electrowetting

February 9, 2024 by Navarre Bartz 7 Comments

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

February 9, 2024 by Maya Posch 17 Comments

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

February 9, 2024 by Tom Nardi 5 Comments

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

February 9, 2024 by Dan Maloney 11 Comments

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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