Your Hard Disk As An Accidental Microphone

October 8, 2017 by Jenny List 30 Comments

We’re used to attaching peripherals to our computers, when we have a need for them to interact with the world around them. An Arduino Uno needs a shield to turn on the lights, for example. Just sometimes though there is the potential for unintended interaction between a computer and the real physical world which surrounds it, and it’s one of those moments that [Alfredo Ortega] has uncovered in his talk at the EKO Party conference in Buenos Aires. He demonstrates how a traditional spinning-rust computer hard disk interacts with vibration in its surroundings, and can either become a rudimentary microphone, or be compromised by sound at its resonant frequency (PDF).

It seems that you can measure the response time of the hard drive head during a read operation without requiring any privilege escalation. This timing varies with vibration, so can be used to reconstruct the sound that the drive is facing. Thus it becomes a microphone, albeit not a very good one with a profoundly bass-heavy response. He goes on to investigate the effect of sound on the drive, discovering that it has a resonant frequency at which the vibration causes it to be unreadable.

Sadly the talk itself appears not yet to be online, but given that previous years’ EKO talks are on YouTube it is likely that when the dust has settled you will be able to see it in full. Meanwhile he’s posted a video demonstration which we’ve posted below the break.

Continue reading “Your Hard Disk As An Accidental Microphone” →

Radio Tuning The Quicksilver Way

October 7, 2017 by Jenny List 58 Comments

Modern radios are often digital affairs, in which the frequency is derived from a stable crystal oscillator and varied through a microprocessor controlled frequency synthesiser. It won’t drift, and it’s exactly on the frequency dialed in. Older radios though relied on a tuned circuit, a combination of capacitor and inductor, for their frequency selection. If you were curious enough to peer inside — and we know you were — you’d have seen the moving vanes of a variable capacitor controlled by the tuning knob.

Of course, there is another way to adjust a tuned circuit: by changing the value of the inductor. Older car radios for instance moved a ferrite slug inside a coil to tune from station to station. But that method is not good enough for [David Mills]. Being in possession of some finely graduated syringes he decided to try liquid tuning by increasing the volume within the coil.

Solutions of salts made little difference, so he reached for some mercury. The result is an RF inductor wound round a syringe body, with a body of mercury whose position can be adjusted by the plunger. He measures the Q factor of the coil with air core or mercury core, and as the inductance decreases with more mercury, so does the Q.

We see home-made parts from time to time, and there’s nothing too special about permeability tuning. However, this unusual take on the matter makes this one rather special. We doubt we’ll see its like very often in the future.

Tape Cutting Bot Trims The Tedium

October 6, 2017 by Jenny List 12 Comments

If you have ever had to assemble a batch of electronic kits, you will know the tedious nature of cutting the tape containing your components. It’s easy enough to count four or five surface-mount resistors and snip them off with a pair of scissors once or twice, but when you are faced with repeating the task a hundred or more times, its allure begins to pale.

[Overflo] faced just such a problem when assembling hundreds of kits for a workshop at the upcoming 34C3 event in Germany. The solution? A tape-cutting robot, of course! (YouTube video, embedded below.)

At the heart of the machine is a pair of scissors operated by a stepper motor, snipping away at the component tape fed by another stepper. An infra-red light barrier sensor counts sprocket holes, and the whole is under the control of an Arduino Pro Mini. An especially clever trick is that the strip passes over a marker pen, allowing different components in a kit to be identified by a color code.

This isn’t the first such approach to this problem we’ve encountered, here’s one that cuts component tape with a laser.

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The Cambridge Z88 Lives! (As A USB Keyboard)

October 5, 2017 by Jenny List 19 Comments

What did [Clive Sinclair] do next? After his line of home computers including the iconic ZX Spectrum hit the buffers and was sold to Amstrad, that is. No longer in the home computer business, he released a portable computer for the business market. The Cambridge Z88 had a Z80 at its heart, a decent keyboard, a text-only LCD display, and ran for an impressively long time on a set of AA alkaline cells. It made a handy portable word-processor, or a serial terminal thanks to its rare-for-the-time RS232 port. And it’s that port that [Spencer Owen] made use of his Z88 in a modern setting, using it as a USB keyboard.

It’s a few years old, so he used a Minimus AVR microcontroller board to provide a serial-to-USB HID keyboard interface, and to keep things tidy he’s made a poor man’s enclosure for it using Sugru. It’s not quite an amazing hardware hack, but we’re featuring it simply for its use of a Z88. Retro computers used as keyboards are a common theme, but a Z88 is a particularly eclectic choice.

If you’re not British you may only know the name [Sinclair] through Brits on the Internet waxing lyrical about their ZX Spectrum computers, but in fact the man behind them is a serial electronics entrepreneur whose career has continued since the 1960s and has touched fields as diverse as portable television and bicycles aside from the computers he is best known for. Often his products took technology to the limit of practicality, but they were and continue to be the ones to watch. If [Clive Sinclair] is working in a field his products may not always hit the right note when released, but you can guarantee that you’ll be buying the same thing from the big boys within a few years. The Z88 is a classic Sinclair product, a little before its time in 1988 and pushing the technology a little too far, but delivering a truly portable and capable computer with a meaningful battery life a couple of decades before you’d find the same attributes from all but a few other niche manufacturers.

Not had enough USB HID devices? How about a Morse key? And if [Spencer] rings a bell, he’s the originator of the RC2014 retrocomputer we reviewed last year.

A 3D Printer Alone Doesn’t Make A Hackspace

October 5, 2017 by Jenny List 75 Comments

There was a time when hackspaces were few and far between — legendary environments that you’d read about online, where amazing projects were made by people who had come together to form communities of creative technology enthusiasts. Of course, they were always in places far afield, California, or Germany, never in provincial England where I call home. Eventually our movement spread its tentacles into the county towns, and several years later with a stint as a hackspace director behind me I sense that it is on the cusp of escaping its underground roots. Every month seems to bring news of yet another organisation wanting to open a makerspace of their own, be they universities, co-working spaces, enterprise centres, libraries, or even banks. It’s evident that our movement has attracted an aura of edginess when it comes to getting things done, and that these entities are anxious to secure a little piece of that for themselves.

So within a few miles of most hackspaces will be several places where you can find a 3D printer, maybe a vinyl cutter, a CAD workstation, and a soldering iron. There will be a fancy hipster coffee machine and some futuristic furniture, and probably some kind of enclosed meeting pod of dubious design. All of which can no doubt be viewed through a glass wall, so that people in suits can watch all that raw #innovation sizzling away.

Viewed from within the movement, it’s easy to see all this activity on the edges of the world of making as a threat. A struggling community organisation survives on its wits alone, it doesn’t have a multi-million pound (or dollar) university or investor behind it. Its tools are hard-won and patched up, and its coffee machine is a battered electric kettle and a jar of supermarket instant coffee. When it comes to gleaming innovation spaces, a group of assorted makers simply can’t compete. Surely the arrival of these spaces will tempt members away, and the hackspace will inevitably wither, and die.

It’s worth taking a step back at this point, and considering what makes a hackspace. Specifically, what makes a good hackspace.

Continue reading “A 3D Printer Alone Doesn’t Make A Hackspace” →

Drag Your Office Aircon Into The 21st Century With Wi-Fi Control

October 3, 2017 by Jenny List 32 Comments

We’ll all have worked in offices that have air-conditioning, but a little too much of it. It’s wonderful on a baking-hot day to walk into the blessèd cool of an air-conditioned office, but after an hour or two of the icy blast you’re shivering away in your summer clothing and you skin has dried out to a crisp. Meanwhile on the other side of the building [Ted] from Marketing has cranked up the whole system to its extreme because he’s got a high metabolism and an office in the full force of the midday sun.

Wouldn’t it be nice if individual air-conditioning units could be easily controlled. To that end, [Maya Posch] has made a rather nicely designed board that takes a NodeMCU board with its ESP8266 processor, and uses four of its outputs as PWM to produce 0-10 volt analogue outputs via filters and op-amps to control individual units. In addition there is an onboard CO2 sensor and a temperature sensor, with provision for an external temperature sensor. The whole fits very neatly into a standard electrical outlet enclosure.

Software wise, the system uses the Sming framework providing an MQTT communication with a backend server that allows the users to control their aircon experience. This is very much a work in progress, so the software has yet to be put up. (Hint, [Maya], hint!) The whole project though is an extremely tidy build, in fact a thing of beauty to a standard you’d expect from a high-quality commercial product. It’s this that tipped the balance into our featuring it before the software is released, it’s one to keep an eye on, because quality like this doesn’t come every day.

This isn’t the first aircon control we’ve brought you, take a look at this one controlled through Slack.

Accidental Satellite Hijacks Can Rebroadcast Cell Towers

October 2, 2017 by Jenny List 21 Comments

A lot of us will use satellite communications without thinking much about the satellite itself. It’s tempting to imagine that up there in orbit is a communications hub and distribution node of breathtaking complexity and ingenuity, but it might come as a surprise to some people that most communications satellites are simple transponders. They listen on one frequency band, and shift what they hear to another upon which they rebroadcast it.

This simplicity is not without weakness, for example the phenomenon of satellite hijacking has a history stretching back decades. In the 1980s for example there were stories abroad of illicit trans-atlantic serial links nestling as unobtrusive single carriers among the broad swathe of a broadcast satellite TX carrier.

Just sometimes, this phenomenon happens unintentionally. Our attention was drawn to a piece by [Harald Welte] on the unintended rebroadcast of GSM base station traffic over a satellite transponder, and of particular interest is the presentation from a conference in 2012 that it links to. The engineers show how they identified their interference as GSM by its timing frames, and then how they narrowed down its source to Nigeria. This didn’t give them the uplink in question though, for that they had to make a downconverter from an LNB, the output of which they coupled to an aged Nokia mobile phone with a wire antenna placed into an RF connector. The Nokia was able to decode the cell tower identification data, allowing them to home in on the culprit.

There was no fault on the part of the GSM operator, instead an unterminated port on the uplink equipment was enough to pick up the GSM signal and introduce it into the transponder as a parasitic signal for the whole of Europe and Africa to hear. Meanwhile the tale of how the engineers identified it contains enough detective work and outright hardware hacking that we’re sure the Hackaday readership will find it of interest.

If satellite hacks interest you, how about reading our thread of posts on the recapture of ISEE-3, or maybe you’d like to listen for a lost satellite from the 1960s.

Thanks [Kia] for the tip.