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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You Can Find Military Radars On Publicly-Available Satellite Data

March 2, 2022 by Lewin Day 15 Comments

When it comes to hunting down military radar installations and associated hardware, we typically think of equipment that is firmly in the price bracket of nation states and their military forces. Whether it’s early warning radar, those used for air defence, or for naval purposes, you’d think it was relatively difficult to intercept or track these emissions.

However, a new tool built by geocomputation lecturer Ollie Ballinger shows this isn’t the case. In fact, openly-available data captured via satellite can be used to find all manner of military radar emitters. Let’s explore how!

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screenshow showing the supposed AllSpice interface. It resembles the GitHub interface, and shows a pull request open to add some ESD protection to a device.

AllSpice Building A Hardware Development Ecosystem For Companies

February 27, 2022 by Arya Voronova 7 Comments

In our “hardware development gets serious” news, we’ve recently learned about AllSpice, a startup building hardware development collaboration infrastructure for companies. Hardware developers are great at building hardware tools for themselves, but perhaps not always so when it comes to software, and AllSpice aims to fill that gap at the “hardware company” level. Nowadays, what commonly happens is that software development tools and integrations are repurposed for hardware needs, and the results aren’t always as stellar as they get in the software world. In other words, AllSpice is learning from the positive outcomes of software industry and building a platform that takes the best parts from these tools, aiming to get to similarly positive outcomes in areas where currently hardware team experiences are lacking.

What AllSpice is building seems to be an umbrella platform designed to augment, integrate and hook into a slew of different already-developed platforms like GitHub, GitLab, Jira (and some other ones), and add much-needed features that large-scale hardware developers can’t afford to maintain and develop themselves. “Design review by screenshot” isn’t unheard of in hardware circles, and likely a thing that everyone of us with hardware collaboration experience has partaken in. On a company scale, there’s a myriad of hardware-related problems like that to solve and polish over.

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Here’s How Those Battery-Free Flashing Phone Stickers Worked

February 26, 2022 by Lewin Day 27 Comments

The late 90s and early 2000s were a breakout time for mobile phones, with cheap GSM handsets ushering in the era in which pretty much everybody had a phone. Back then, a popular way to customize one’s phone was to install a sticker that would flash when the phone rang. These required no batteries or any other connection to the phone, and [Big Clive] has dived in to explain how they worked.

The simple schematic of the flashing sticker circuit. The flashing was generated by the pulses of RF energy from the smartphone.

It’s an old-fashioned teardown that requires a bit of cutting to get inside the sticker itself. A typical example had three LEDs in series for a total voltage drop of around 7V, hooked up to two diodes and a PCB trace antenna. A later evolution used raw unpackaged components bonded to the PCB. Future versions went down to a single diode, using the LEDs to serve as the second. The basic theory was that the PCB traces would pick up RF transmitted by the phone when a call was coming in, lighting the LEDs.

In the 2G era, the freuqencies used were on the order of 300 MHz to 1.9GHz. A combination of the change in frequencies used by modern phone technology and the lower transmit powers used by handsets means that the stickers don’t work properly with modern phones according to [Big Clive].

Incidentally, you might like to consider running your own old-school cellphone network. Video after the break.

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A 3D-printed mechanical system that moves weather symbols around

3D Printed Mechanical Contraption Shows Live Weather Forecast

February 26, 2022 by Robin Kearey 3 Comments

“What’s the weather going to be like today?” is a question that’s near-permanently on the mind of those living in places like Britain, where brilliant sunshine can follow thick clouds, only to turn into drizzle an hour later. Nowadays you simply need to glance at your phone to know whether you need to pack an umbrella, but where’s the fun in that? Why not have a huge mechanical display to show you a summary of today’s weather?

As a fan of automatons and other contraptions filled with gears and pulleys, [Mike] decided to build just such a machine for his latest Mikey Makes video. It uses brightly coloured indicators inspired by the BBC’s famous “fluffy cloud” symbols that can show various combinations of sunshine, clouds, rain and snow. These symbols are moved around by dozens of gears, levers, swinging arms and other moving parts which were all 3D printed. We especially like the system that folds out rays of sunshine from behind the cloud; you can see it working in the video embedded below.

Live weather data is fetched through an open weather API by an Arduino MKR WiFi 1010. This then drives the mechanical system through a pair of motor driver ICs. The heavy work is performed by stepper motors and servos, while micro-switches and optical detectors determine the end point of each movement.

If you’re into weather displays, you’re in luck: we’ve featured many different styles over the years, including e-paper screens, analog gauges, split-flap displays and even a miniature recreation of the local weather.

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Ray Tracing On A Modern TI Graphing Calculator

February 21, 2022 by Maya Posch 16 Comments

Something being impractical isn’t any reason not to do it, which is why just about anything with a CPU in it can run Doom by now. For the same reason there obviously is a way to do ray tracing of 3D scenes on a modern-day TI-84 Plus CE graphical calculator. This is excellent news for anyone who has one of these calculators, along with a lot of time, perhaps during boring classes, to spare.

As [TheScienceElf] demonstrates in a video, also embedded after the break, it’s not quite the real-time experience one would expect from an NVidia RTX 30-series GPU. Although the eZ80-based CPU in the calculator is significantly more efficient than a Z80 as found in many 1980s home computers, the demo scene at standard resolution takes about 12 minutes to render, as also noted on the GitHub project page.

Perhaps the most interesting part about this project is its use of the Clang-based C & C++ toolchain for the TI-84 Plus CE which gives easy access to the calculator’s hardware and related, including graphics, file I/O, fonts, keypad input and more. Even if using a TI-84 Plus CE to render the next Pixar-level movie isn’t the most productive use imaginable for these devices, this project and the CE toolchain make it all too easy to tinker with these $150 devices.

It would also offer a nice change of pace from writing Snake in TiBASIC, a BASIC dialect in which [TheScienceElf] incidentally has also written a ray tracer.

(Thanks to [poiuyt] for the tip)

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On the left, four through-hole USB-C connectors laid out on a purple cutting mat. On the right, a teardown picture shows that there's neither resistors nor CC connections inside such a connector, resulting in consequences described in the article.

The USB-C Connectors You Never Knew You Wanted To Avoid

February 20, 2022 by Arya Voronova 24 Comments

On Tech Twitter, some people are known for Their Thing – for example, [A13 (@sad_electronics)], (when they’re not busy designing electronics), searches the net to find outstanding parts to marvel at. A good portion of the parts that they find are outstanding for all the wrong reasons. Today, that’s a through-hole two-pin USB Type-C socket. Observing the cheap tech we get from China (or the UK!), you might conclude that two 5.1K pulldown resistors are very hard to add to a product – this socket makes it literally impossible.

We’ve seen two-pin THT MicroUSB sockets before, sometimes used for hobbyist kits. This one, however, goes against the main requirement of Type-C connectors – sink (Type-C-powered) devices having pulldowns on CC pins, and source devices (PSUs and host ports) having pull up resistors to VBUS. As disassembly shows, this connector has neither of these nor the capability for you to add anything, as the CC pins are physically not present. If you use this port to make a USB-C-powered device, a Type-C-compliant PSU will not give it power. If you try to make a Type-C PSU with it, a compliant device shall (rightfully!) refuse to charge from it. The only thing this port is good for is when a device using it is bundled with a USB-A to USB-C cable – actively setting back whatever progress Type-C connectors managed to make.

As much as USB Type-C basics are straightforward, manufacturers get it wrong on the regular – back in 2016, a wrong cable could kill your $1.5k MacBook. Nowadays, we might only need to mod a device with a pair of 5.1K resistors every now and then. We can only hope that the new EU laws will force devices to get it right and stop ruining the convenience for everyone, so we can finally enjoy what was promised to us. Hackers have been making more and more devices with USB-C ports, and even retrofitting iPhones here and there. If you wanted to get into mischief territory and abuse the extended capabilities of new tech, you could even make a device that enumerates in different ways if you flip the cable, or make a “BGA on an FPC” dongle that is fully hidden inside a Type-C cable end!