One Man’s Tale Of EMC Compliance Testing

If you turn over almost any electronic device, you should find all those compliance logos: CE, FCC, UL, TÜV, and friends. They mean that the device meets required standards set by a particular region or testing organisation, and is safe for you, the consumer.

Among those standards are those concerning EMC, or ElectroMagnetic Compatibility. These ensure that the device neither emits RF radiation such that it might interfere with anything in its surroundings, nor is it unusually susceptible to radiation from those surroundings. Achieving a pass in those tests is something of a black art, and it’s one that [Pero] has detailed his exposure to in the process of seeing a large 3-phase power supply through them. It’s a lengthy, and fascinating post.

He takes us through a basic though slightly redacted look at the device itself, before describing the testing process, and the EMC lab. These are fascinating places with expert staff who can really help, though they are extremely expensive to book time in. Since the test involves a mains power supply he describes the Line Impedance Stabilisation Network, or LISN, whose job is to safely filter away the RF component on the mains cable, and present a uniform impedance to the device.

In the end his device failed its test, and he was only able to achieve a pass with a bit of that black magic involving the RF compliance engineer’s secret weapons: copper tape and ferrite rings. [Pero] and his colleagues are going to have to redesign their shielding.

We’ve covered our visits to the EMC test lab here before.

A Converter You Won’t Have: PS/2 Mouse To Serial Mouse

When did you last buy a mouse? Did it have a little adapter in the box? There was a time when if you bought a USB mouse, in the box was also an adapter to allow it to be used with the older PS/2 interface. And if you were to go back a few more years into the past, you’d have found when you bought a mouse with a PS/2 connector fitted, it may well have come with an adapter for a 9-pin RS232 serial port. Those mice from a decade or more ago would have contained the software to recognise the interface into which they were plugged, and emulate it accordingly. It is unlikely then that you could take a modern USB-only device and an unholy chain of USB-to-PS/2-to-serial adapters, and have it work as a serial mouse. Want to run Windows 3.1 on a 386DX? You need a serial mouse.

Happily, [matze525] has come along with a solution for those of you with a need to drive an ancient PC with a serial mouse. He’s created a PS/2 to RS232 mouse converter, and it takes the form of a little PCB with an AT90S2313P microcontroller to do the translation and an RS232 level converter chip.

It might sound like a rather unexpected device to produce, but we can see it fills an important niche. In the early 1990s mice were not the reliable optical devices we have today, instead they had nasty mechanical connections inside, or if you were extremely lucky, optical encoder wheels. The supply of still-reliable RS232 mice must therefore be dwindling, and if you have a Windows 3.1 PC to keep alive then we can see the ability to use a more modern pointing device has a lot going for it.

If you have one of those machines from that era that came with proprietary interfaces, maybe you can make use of a USB to quadrature converter.

Typhoon-proof Wind Turbine

While wind energy is rapidly increasing its market share across the world, wind turbines are not able to be constructed everywhere that they might be needed. A perfect example of this is Japan, where a traditional wind turbine would get damaged by typhoons. After the Fukushima disaster, though, one Japanese engineer committed himself to building a turbine specifically for Japan that can operate just fine within hurricane-force winds. (YouTube, embedded below.)

The “typhoon turbine” as it is known works via the Magnus effect, where a spinning object directs air around it faster on one side than on the other. This turbine uses three Magnus effect-driven cylinders with a blade on each one, which allows the turbine to harvest energy no matter how high the wind speeds are. The problem with hurricanes and typhoons isn’t just the wind, but also what the wind blows around. While there is no mention of its impact resistance it certainly looks like it has been built as robustly as possible.

Hopefully this turbine is able to catch on in Japan so they can reduce their reliance on other types of energy. Wind energy has been getting incredibly popular lately, including among hikers who carry a portable wind generator, and even among people with just a few pieces of scrap material.

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Screwdriving

Screwdriving! It’s like wardriving but instead of discovering WiFi networks, the aim is to discover Bluetooth Low Energy (BLE)  devices of a special kind: adult toys. Yes, everything’s going to be connected, even vibrators. Welcome to the 21st century.

Security researcher [Alex Lomas] recently found that a lot of BLE-enabled adult toys are completely vulnerable to malicious attacks. In fact, they are basically wide open to anyone by design.

“Adult toys lend themselves to being great testbeds for IoT research: they’re BLE, they’re relatively cheap, they’re accessible and have companion apps for the full spectrum of testing.”

Yes… great test beds… Erm, anyway, [Alex Lomas] found that there is no PIN nor password protection, or the PIN is static and generic (0000 / 1234) on every Bluetooth adult toy analysed. Manufacturers don’t want to go through the hassle, presumably because sex toys lack displays that would enable a classic Bluetooth pairing, with random PIN and so on. While this might be a valid point, almost all electronic appliances have an “ON/OFF” button for input and some LED (or even vibration in these cases) that allow some form of output. It could be done, and it’s not like vibrators are the only minimalistic appliances out there in the IoT world.

Although BLE security is crippled by design (PDF), it is possible to add security on top of flawed protocols. The average web-browser does it all the time. The communications don’t have to be clear-text where you can literally see “Vibrate:10” flying around in packets. Encryption could be implemented on top of the BLE link between the app and the device, for instance. Understandably, security in some devices is not absolutely critical. That being said, the security bar doesn’t have to be lowered to zero — it’s not safe for work or play.

[via Arstechnica]

Zenith’s New Watch Oscillator is Making Waves

Swiss watchmaker Zenith has created what many mechanical watch fanatics are calling the biggest improvement to mechanical watch accuracy since the invention of the balance spring in 1675. The Caliber ZO 342 is a new type of harmonic oscillator that runs at 15 Hz, which is almost four times the speed of most watches. The coolest part? It’s fabricated out of silicon using Deep Reactive Ion Etching (DRIE), and it single-handedly replaces about 30 components.

Before explaining how Zenith’s oscillator works and why this is such exciting news, it’s important to understand why the balance spring and balance wheel were such a big step forward when they were the newest thing. The system was invented by [Christiaan Huygens], a Dutch mathematician and scientist. [Huygens] had previously invented the pendulum clock, which is widely accepted as the first precision timepiece.

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This 3D Printer Enclosure Takes Ventilation Seriously

A lot of work has gone into hacking common items (like IKEA Lack tables) into useful and effective 3D printer enclosures, but [Stefan.Lu] has taken a harder look at the whole business. He decided to start with some specific goals that were unmet by current solutions. In particular, he wanted to allow for proper ventilation and exhaust. Not only do some filaments smell bad, but there is ongoing research around UFP (ultra-fine particles) emitted from the 3D printing process. Just in case UFPs turn out to be this generation’s asbestos or something equally terrible, [Stefan.Lu] felt that a bit more work and expense up front would be worth it to meet his goals of a ventilation-friendly enclosure.

In addition to ventilation and exhaust, [Stefan.Lu] wanted to locate the printer at a comfortable working height, and preferred not to build things entirely from scratch. He did it for well under $200 by using a common storage rack shelf as the foundation and acrylic panels for the sides, and a few thoughtful uses of basic hardware. The angled metal supports made for easy attachment points and customization, and a combination of solid shelf plus anchoring to the wall put an end to vibrations. The side panels are secured by magnets, and [Stefan.Lu] points out that if you don’t have access to a laser cutter, cast acrylic withstands drilling and cutting better than extruded acrylic.

The final touch was a fire alarm, which is an excellent precaution. 3D printers are heating elements with multiple moving parts and they often work unattended. It makes sense to have a fire alarm around, or at least not enclose the device in highly flammable material in the first place.