Author: Jenny List

3309 Articles

One Person’s Experience Of Having PCB Assembly Done In China

August 7, 2017 by 41 Comments

Those of us who have our PCBs manufactured by Chinese PCB fab houses will be used to seeing tempting offers to also assemble our completed boards. Send the Gerbers as normal, but also send a BoM, and for an extra slice of cash you can receive fully assembled PCBs instead of just bare boards. It sounds alluring, but leaves a few questions for those without the experience. How much will it cost, what will the quality be like, and will my boards work? [Alexander Lang] had a limited run of ten small pressure sensor boards to make, and since his board house had started an assembly service,  decided to take the plunge and opt for full assembly.

His first step was to assemble his BoM and send it with the Gerbers. He is at pains to stress that the BoM is key to the whole project, and getting it right with the correct packages and more than one source for each component is critical. The board house first charged him £32.05 ($41.76) to make his PCBs and stencil, and assess his BoM for a build quote. A few days passed, and then he had a quote for assembly, £61.41 ($80). He placed the order, the board house processed it and made the boards, and in due course his working PCB modules arrived.

This might sound at this point like an unexciting saga, but its very smoothness is the key to what makes it interesting. Those of us who have wondered about the risks involved in taking up such a service need to hear stories like this one as surely as we do stories of failure, because without them we’re flying blind. Whether £93.46 ($121.76) for ten small boards represents good enough value is another matter, but if surface-mount soldering is not your thing you might be interested to follow [Alexander]’s example. After all, it wasn’t so long ago that getting a cheap PCB made in China was a similar leap of faith.

A New Battery For A Potted Clock Module

August 6, 2017 by 31 Comments

If you did much dismantling of PCs back in the 1980s and 1990s, you might be familiar with the Dallas Semiconductor range of potted real-time clock modules. These were chunky dual-in-line devices containing clock and non-volatile RAM chips, a crystal, and a lithium battery. The battery was good for about a decade, which was fine for most PCs of the day because the majority of desktop computers are replaced long before that deadline.

[Glitch], however has an industrial single-board computer with a 486 processor that has had a life much more prolonged than its desktop siblings due to its application. The battery in the onboard Dallas DS1387 has long ago expired, and since these devices are so long out of production to be unavailable, he’s had to improvise.

Improving on some previous documented projects he found through an internet search, he carefully ground away the potting compound to reveal a couple of the battery conductors, cut them with a PCB drill, and mounted a lithium cell holder on the top of the device with some tidily soldered Kynar wires to bring in the power. A CR1225 cell was used rather than the ubiquitous CR2032, as space was at a premium in the width of the ISA card form factor.

The potted RTC module is something of a rare device these days, but if you have a retro computer containing one this seems to be a very useful piece of work to bring it back to life. We’ve covered another similar one with a slightly larger battery in the past.

Hackaday Prize Entry: A Six Axis Robotic Arm With Fingertip Control

August 4, 2017 by 3 Comments

If you were a child of the 1980s whose fascination extended to the contents of your local Radio Shack store, you may remember the Armatron robot arm as a particular object of desire. It was a table top robot arm operated not by motors or a microcontroller, but by a clever set of gears directed manually from a pair of joysticks. If you took a look at it with an eye to control from your 8-bit home computer you were likely to be disappointed, but nevertheless it was an excellent toy.

The Armatron may be long gone, but if you hanker for a similar device you should take a look at [3D Meister]’s finger controlled six axis arm. This is an arm similar to the Armatron in size, but with far more capabilities. Control is via cable loops to sliders at the arm’s base, and in addition to the usual arm movements there is an extra loop which can be used to operate any of a selection of tools including a gripper, a magnet, and a clipper. The video below the break shows the arm in action, and for the faint-hearted it should be noted that it contains the gratuitous death of some innocent plants.

Continue reading “Hackaday Prize Entry: A Six Axis Robotic Arm With Fingertip Control” →

The Amazon Echo As A Listening Device

August 3, 2017 by 31 Comments

It is an inevitability that following swiftly on the heels of the release of a new device there will be an announcement of its rooting, reverse engineering, or other revealing of its hackability. Now the device in question is the Amazon Echo, as MWR Labs announce their work in persuading an Echo to yield the live audio from the microphone and turn the voice assistant device into a covert listening device.

The work hinges on a previous discovery and reverse engineering (PDF) of Amazon’s debug connector on the base of the Echo, which exposes both an SD card interface and a serial terminal. Following that work, they were able to gain root access to the device, analyze the structure of the audio buffers and how the different Echo processes use them, and run Amazon’s own “shmbuf_tool” application to pipe raw audio data to a network stream. Astoundingly this could be done without compromising the normal operation of the device.

It should be stressed, that this is an exploit that requires physical access to the device and a bit of knowledge to perform. But it’s not inconceivable that it could be made into a near-automated process requiring only a device with a set of pogo pins to be mated with an Echo that has had its cover quickly removed.

That said, inevitably there will be enough unused Echos floating around before too long that their rootability will make them useful to people in our community. We look forward to what interesting projects people come up with using rooted Echos.

This isn’t the first time we’ve covered the use of an Echo as a listening device.

Via Hacker News.

Amazon Echo image: FASTILY [CC BY-SA 4.0].

Avoiding The Engineer-Saviour Trap

August 3, 2017 by 94 Comments

The random seaside holidays of Hackaday staffers rarely sow the seeds of our articles, but my most recent trip had something slightly unusual about it. I was spending a couple of days in a resort town on the Isle of Wight, just off the coast of Southern England, and my hotel was the local outpost of a huge chain that provides anonymous rooms for travelling salesmen and the like. I could probably find an identical place to lay my head anywhere in the world from Anchorage to Hobart and everywhere in between.

My room though was slightly different to the norm. By chance rather than necessity I’d been assigned one of the hotel’s accessible rooms, designed with people with disabilities in mind. And once I’d reached the limit of the free amusement that the digital TV channels of Southern England could provide, my attention turned to the room itself, eyeing up its slightly unfamiliar design features as an engineer.

Continue reading “Avoiding The Engineer-Saviour Trap” →

Getting Data Out Of Air-Gapped Networks Through The Power Cable

August 1, 2017 by 28 Comments

If you are an organisation that is custodian of sensitive information or infrastructure, it would be foolhardy of you to place it directly on the public Internet. No matter how good your security might be, there is always the risk that a miscreant could circumvent it, and perform all sorts of mischief. The solution employed therefore is to physically isolate such sensitive equipment from the rest of the world, creating an air gap. Nothing can come in and nothing can go out, or so goes the theory.

Well, that’s the theory, anyway. [Davidl] sends us some work that punches a hole in some air-gapped networks, allowing low-speed data to escape the air gap even if it doesn’t allow the reverse.

So how is this seemingly impossible task performed? The answer comes through the mains electrical infrastructure, if the air gap is bridged by a mains cable then the load on that mains cable can be modulated by altering the work undertaken by a computer connected to it. This modulation can then be detected with a current transformer, or even by compromising a UPS or electricity meter outside the air gap.

Of course, the Hackaday readership are all upstanding and law-abiding citizens of good standing, to whom such matters are of purely academic interest. Notwithstanding that, the article goes into the subject in great detail, and makes for a fascinating read.

We’ve touched on this subject before with such various techniques as broadcast radio interference and the noise from a fan,  as well as with an in-depth feature.

Amateur Radio Just Isn’t Exciting

August 1, 2017 by 171 Comments

As ARRL president, [Rick Roderick, K5UR] spends a significant amount of time proselytising the hobby. He has a standard talk about amateur radio that involves tales gleaned from his many decades as a licence holder, and features QSL cards from rare DX contacts to show how radio amateurs talk all over the world.

He’s delivered this talk countless times, and is used to a good reception from audiences impressed with what can be done with radio. But when he delivered it to a group of young people, as Southgate ARC reports, he was surprised to see a lack of interest from his audience, to whom DX or contesting just don’t cut it when they have grown up with the pervasive Internet. Writing in the 2016 ARRL Annual Report, he said:

“Change generally doesn’t come easy to us. But when I looked out at that group of young faces and saw their disinterest in traditional ham pursuits, I realized that I had to change. We have to change. It won’t come easy, but it’s essential that we get to work on it now.”

If you were to profile a typical group of radio amateurs, it would not be difficult to see why [K5UR] found himself in this position. It might be an unflattering portrait for some amateurs, but it’s fair to say that amateur radio is a hobby pursued predominantly by older more well-off men with the means to spend thousands of dollars on commercial radios. It is also fair to say that this is hardly a prospect that would energize all but the most dedicated of youthful radio enthusiasts. This is not a new phenomenon, where this is being written it was definitely the case back in the days when they were issuing G7 callsigns, for instance.

Were Hackaday to find ourselves in the position of advising the ARRL on such matters, we’d probably suggest a return to the roots of amateur radio, a time in the early 20th century when it was the technology that mattered rather than the collecting of DXCC entities or grid squares, and an amateur had first to build their own equipment rather than simply order a shiny radio before they could make a contact. Give a room full of kids a kit-building session, have them make a little radio. And lobby for construction to be an integral part of the licensing process, it is very sad indeed that where this is being written at least, the lowest tier of amateur radio licence precludes home-made radio equipment. Given all that, why should it be a surprise that for kids, amateur radio just isn’t exciting?

We’ve shown you some fantastic amateur radio builds over the years. If you have a youngster with an interest in radio, show them a BitX transceiver, or the world of QRP.

Header image: enixii. [CC BY 2.0]. We hope these snoozing kids aren’t in the middle of a lecture on amateur radio.