One Stepper Plus A Whole Bunch Of Magnets Equals A Unique Seven-Segment Display

March 5, 2022 by Dan Maloney 24 Comments

Sometimes the cost of simplicity is extra complexity. It seems counterintuitive, but it seems to be true. And this single-motor mechanical seven-segment display seems to be a perfect example of this paradox.

On second thought, [aeropic]’s mechanism isn’t really all that mechanically complicated, but there sure was a lot of planning and ingenuity that went into it. The front has a 3D-printed bezel with the familiar segment cutouts, each of which is fitted with a pivoting segment, black on one side and white on the other.

Behind the bezel is a vertical shaft with three wheels, one behind each horizontal segment, and a pair of horizontal shafts, each with two wheels behind each vertical segment. The three shafts are geared to turn together by a single stepper in the base. Each wheel has ten magnets embedded in the outer circumference, with the polarity oriented to flip the segment in front of it to the right orientation for the current digit. It’s probably something that’s most easily understood by watching the video below.

We’ve seen quite a few of these mechanical seven-segment displays lately — this cam-and-servo mechanism comes to mind. We love them all, of course, but the great thing about [aeropic]’s display is how quiet it is — the stepper is mostly silent, and the segments make only a gentle clunk when they flip. It’s very satisfying.

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Hackaday Podcast 158: Phased Array Physics, CRTs Two Ways, A Micro Microcontroller, And A Surgically Implanted Red Herring

March 4, 2022 by Dan Maloney 1 Comment

Join Editor-in-Chief Elliot Williams and Staff Writer Dan Maloney as they take a look at the week’s top stories, taken straight off the pages of Hackaday. What happens when you stuff modern parts into a 90’s novelty PC case? Nothing good, but everything awesome! Is there any way to prevent PCB soil moisture sensors from being destroyed by, you know, soil moisture? How small is too small for a microcontroller, and who needs documentation anyway? We also cast a jaundiced eye — err, ear — at an electronic cheating scandal, and if you’ve ever wondered how phased arrays and beam steering work, gazing into a pan of water might just answer your questions. We also share all our soldering war stories, and hey — what’s with all these CRT projects anyway?

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct Download (52 MB, but sounds like at least 58 MB!)

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Big LED Matrix Becomes Tiny LED Matrix Thanks To Fiber Optics

March 1, 2022 by Dan Maloney 11 Comments

Everyone loves LED matrices, and even if you can’t find what you like commercially, it’s pretty easy to make just what you want. Need it big? No problem; just order a big PCB and some WS2812s. Need something tiny? There are ridiculously small LEDs that will test your SMD skills, as well as your vision.

But what if you want a small matrix that’s actually a big matrix in disguise? For that, you’ll want to follow [elliotmade]’s lead and incorporate fiber optics into your LED matrix. The build starts with a 16×16 matrix of WS2812B addressable LEDs, with fairly tight spacing but still 160 mm on a side. The flexible matrix was sandwiched between a metal backing plate and a plastic bezel with holes directly over each LED. Each hole accepts one end of a generous length of flexible 1.5-mm acrylic light pipe material; the other end plugs into a block of aluminum with a 35 by 7 matrix of similar holes. The small block is supported above the baseplate by standoffs, but it looks like the graceful bundle of fibers is holding up the smaller display.

A Raspberry Pi Pico running a CircutPython program does the job of controlling the LEDs, and as you can see in the video below, the effect is quite lovely. Just enough light leaks out from the fibers to make a fascinating show in the background while the small display does its thing. We’ve seen a few practical uses for such a thing, but we’re OK with this just being pretty. It does give one ideas about adding fiber optics to circuit sculptures, though.

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Sprockets And Chains Drive This Unique Mechanical Digital Clock

March 1, 2022 by Dan Maloney 17 Comments

When it comes to mechanical timepieces, we’re used to seeing mechanisms stuffed with tiny gears and wheel, often of marvelous complexity and precision. What we’re perhaps less used to seeing is a clock that uses chains and sprockets, and that looks more like what you’d find on a bicycle on your typical bicycle.

We can’t recall seeing anything quite like [SPE]’s “Time Machine” before. It’s one of those builds that explains itself by watching it work, so check out the video below and you’ll see where this one is going. The clock has three loops of roller link chain, each of which has a series of numbers welded to the links. The loops of chain are advanced around sprockets by a trio of geared-down motors, with the numbers standing up straight at the top of each loop. A microcontroller keeps track of the time and starts the clock advancing every minute, but a series of microswitches that are activated by the passing chain do all the rest of the control — sounds like a perfect time to say, “Could have used a 555,” but we still think it’s great the way it is.

Surprisingly, [SPE]’s clock seems like it wouldn’t be that hard to live with. Many unique electromechanical clocks that we feature, like a clock that’s nothing but hands or The Time Twister, are a little on the noisy side. While “Time Machine” isn’t exactly silent, its whirring isn’t terrible, and even though its clicks are a little loud, they’ve got a satisfying mechanical sound to them.

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Old Portable TV Becomes Unique CRT Cyberdeck

February 28, 2022 by Dan Maloney 10 Comments

Remember the “suitcase” form-factor for PCs? In the time before latops, these luggable machines were just the thing for the on-the-go executive. OK, maybe not really — but the ability to have PC, monitor, and peripherals in a single package had real appeal, and a lot of that rationale is behind the cyberdeck phenomenon. So when we saw this retro portable TV turned into a cyberdeck, it really caught our eye.

Ironically, the portable black-and-white TV that [Lucas Dul] chose as the basis for his cyberdeck hails from about the same period in time that luggable PCs were having their brief time in the sun. Scored from eBay, the Magnavox TV/radio combo had seen better days, and required a bit of surgery to repair what might have been drop damage. With the CRT restored and the video and audio paths located, the TV got a Raspberry Pi, a small touchpad, and a couple of concealed USB connectors. The Pi’s composite output drives the CRT, with about the results you’d expect. The keyboard appears to be just about the right size to serve as a cover, but [Lucas] said that’s a future project.

Still, with the TV’s original handle acting as a stand, this cyberdeck gives off a real Compaq or IBM portable PC vibe. We’ve seen a few luggable-lookalike cyberdecks before, but none that dared use a CRT monitor. It may be a far cry from HDMI, but we really appreciate that [Lucas] chose this way rather than slapping in an LCD.

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Logic Simulation Hack Chat With Al Williams

February 28, 2022 by Dan Maloney 3 Comments

Join us on Wednesday, March 2 at noon Pacific for the Logic Simulation Hack Chat with Al Williams!

Many of us probably remember — some fondly, some less so — our first encounter with a truth table. The little grid of ones and zeros seemed simple enough, but it held real power in its tabular representation of the output of a logic circuit for a given set of inputs. It’s what makes more complex logic circuits possible, but only up to a point — add enough gates, flip flops, and counters, and keeping track of what’s high and what’s low becomes problematic with just pencil and paper.

If you’ve reached the point where keeping your digital design in your head doesn’t work anymore, or if you never could keep your NANDs and NORs straight, then you’re ready for a digital logic simulator. Applications like Falstad and LogiSim let you build a design using everything from discrete logic gates to complete assemblies like adders, counters, and even arithmetic logic units. Add in some passives like capacitors and inductors, and a logic simulator may be the only tool you need to bring a design to life in the virtual world before ever touching a breadboard.

To help us figure out where logic simulators fit in our design processes, Hackaday Staff Writer Al Williams will hop onto the Hack Chat with us. Al ran a very successful FPGA Bootcamp series back in 2018, which included a review of digital logic using Falstad. He’ll expand on that in this Hack Chat, so come along with your questions and comments. You won’t want to miss this one!

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, March 2 at 12:00 PM Pacific time. If time zones have you tied up, we have a handy time zone converter.

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Hackaday Links: February 27, 2022

February 27, 2022 by Dan Maloney 15 Comments

If there’s one thing that can trigger people, it’s the printer racket. Printer manufacturers who put DRM-like features into their consumables are rightly viewed as Satan’s spawn, and while these monsters have been content so far to only put digital rights management features into their ink and toner cartridges, they appear to now have their rapacious gaze set on print media too. At least according to the good folks over at the Electronic Frontier Foundation, who claim that Dymo’s latest generation of label printers will have RFID tags in the label cartridges, apparently to prevent consumers from buying non-Dymo media. The company doesn’t bill it as a way to lock you into their exorbitantly priced consumables, of course; rather, this is an exciting new feature that’s called “Automatic Label Recognition,” which keeps track of what labels are installed and how many are left. Of course, this is just red meat to people like us, and we fully expect to see workarounds in the not-to-distant future.

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