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Fix Your Insecure Amazon Fire TV Stick

April 18, 2018 by 48 Comments

I recently spent a largely sleepless night at a hotel, and out of equal parts curiosity and boredom, decided to kill some time scanning the guest network to see what my fellow travelers might be up to. As you’d probably expect, I saw a veritable sea of Samsung and Apple devices. But buried among the seemingly endless number of smartphones charging next to their sleeping owners, I found something rather interesting. I was as picking up a number of Amazon-made devices, all of which had port 5555 open.

As a habitual Android tinkerer, this struck me as very odd. Port 5555 is used for Android Debug Bridge (ADB), a development tool used to control and perform various administrative tasks on an Android device over the network or (more commonly) locally over USB. The number of users who would have legitimately needed to enable network ADB on their devices is surely rather low, so to see a half dozen of them on the network at the same time seemed improbable to say the least.

Why would so many devices manufactured by Amazon all have network ADB enabled? I realized there must be a connection, and it didn’t take long to figure it out.

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TensorFlow In Your Browser

April 16, 2018 by 24 Comments

If you want to explore machine learning, you can now write applications that train and deploy TensorFlow in your browser using JavaScript. We know what you are thinking. That has to be slow. Surprisingly, it isn’t, since the libraries use Graphics Processing Unit (GPU) acceleration. Of course, that assumes your browser can use your GPU. There are several demos available, include one where you train a Pac Man game to respond to gestures in your webcam to control the game. If you try it and then disable accelerated graphics in your browser options, you’ll see just what a speed up you can gain from the GPU.

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Two-Cent Temperature Sensors

April 16, 2018 by 89 Comments

When they need to add temperature control to a project, many hackers reach for a K-type thermocouple for their high-temperature needs, or an integrated temperature-sensing IC when it doesn’t get that hot. The thermocouple relies on very small currents and extremely high gain, and you pretty much need a dedicated IC to read it, which can be expensive. The ICs aren’t as expensive, but they’re basically limited to boiling water. What do you do if you want to control a reflow oven?

There’s a cheaper way that spans a range between Antarctic winter and molten solder, and you’ve probably already got the parts on your shelf. Even if you don’t, it’s only going to run you an extra two cents, assuming that you’ve already got a microcontroller with an ADC in your project. The BOM: a plain-vanilla diode and a resistor.

I’ve been using diodes as temperature sensors in three projects over the last year: one is a coffee roaster that brings the beans up to 220 °C in hot air, another is a reflow hotplate that tops out around 210 °C, and the third is a toner-transfer iron that holds a very stable 130 °C. In all of these cases, I don’t really care about the actual numerical value of the temperature — all that matters is reproducibility — so I never bothered to calibrate anything. I thought I’d do it right for Hackaday, and try to push the humble diode to its limits for science.

What resulted was a PCB fire, test circuits desoldering themselves above 190 °C, temperature probes coming loose, and finally a broken ramekin and 200 °C peanut oil all over my desk. Fun times! On the other hand, I managed to get out enough data to calibrate some diodes, and the results are fantastic. The circuits under test included both best practices and the easiest thing that could possibly work, and the results are pretty close. This is definitely a technique that you want to have under your belt for most temperature ranges. The devil is in the details, of course, so read on!

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Custom Built Vacuum Tube Cassette Player

April 16, 2018 by 40 Comments

As we’ve said many times here on Hackaday, it’s not our place to question why people make the things they make. There’s a legitimate need or utility for many of the projects we cover, no doubt about it. But there’s also a large number of them which are so convoluted that they border on absurd. Not that we love the crazy ones any less, in fact, we usually like those the best.

So when we saw this incredible modification to a Panasonic RN-404 microcassette recorder which replaces the audio hardware with a custom built vacuum tube amplifier, we didn’t bother asking what the point was. Perhaps it’s an attempt to make the most impractical method for recording and playing back audio, or maybe it was just to see if it was possible. No matter why it was done, it’s here now and it’s absolutely glorious.

If the look of the hardware didn’t tip you off that this project makes use of old Soviet-era components, the video after the break certainly will. Specifically, it’s using 1ZH25R and 1S38A tubes which were originally intended for military use. Just like all cool old Soviet tech was. Say what you will about the Cold War, it certainly got the engineering juices flowing.

There’s quite a bit of information about how these ancient tubes were brought back to life by way of this gorgeous home-etched PCB. Suffice to say, working with tubes is an art to begin with, but working with such small and unique ones is on a whole new level.

This isn’t the first time we’ve seen some tiny tubes make their way into a piece of consumer audio equipment, but this one certainly takes the top spot in terms of professional final results.

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Mechanisms: The Spring

April 13, 2018 by 64 Comments

Most people probably don’t think about springs until one kinks up or snaps, but most of the world’s springs are pretty crucial. The ones that aren’t go by the name Slinky.

We all use and encounter dozens of different types of springs every day without realizing it. Look inside the world of springs and you’ll find hundreds of variations on the theme of bounce. The principle of the spring is simple enough that it can be extended to almost any shape and size that can be imagined and machined. Because it can take so many forms, the spring as a mechanism has thousands of applications. Look under your car, take apart a retractable pen, open up a stapler, an oven door, or a safety pin, and you’ll find a spring or two. Continue reading “Mechanisms: The Spring” →

Another Reason To Learn Morse Code: Kidnapping

April 13, 2018 by 81 Comments

Morse code — that series of dots and dashes — can be useful in the strangest situations. As a kid I remember an original Star Trek episode where an injured [Christopher Pike] could only blink a light once for yes and twice for no. Even as a kid, I remember thinking, “Too bad they didn’t think to teach him Morse code.” Of course odd uses of Morse aren’t just for TV and Movies. Perhaps the strangest real-life use was the case of the Colombian government hiding code in pop music to send messages to hostages.

In 2010, [Jose Espejo] was close to retirement from the Colombian army. But he was bothered by the fact that some of his comrades were hostages of FARC (the Revolutionary Armed Forces of Colombia; the anti-government guerrillas), some for as many as ten years. There was a massive effort to free hostages underway, and they wanted them to know both to boost morale and so they’d be ready to escape. But how do you send a message to people in captivity without alerting their captors?

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Hacking When It Counts: Pigeon-Guided Missiles

April 11, 2018 by 51 Comments

The image of the crackpot inventor, disheveled, disorganized, and surrounded by the remains of his failures, is an enduring Hollywood trope. While a simple look around one’s shop will probably reveal how such stereotypes get started, the image is largely not a fair characterization of the creative mind and how it works, and does not properly respect those who struggle daily to push the state of the art into uncharted territory.

That said, there are plenty of wacky ideas that have come down the pike, most of which mercifully fade away before attracting undue attention. In times of war, though, the need for new and better ways to blow each other up tends to bring out the really nutty ideas and lower the barrier to revealing them publically, or at least to military officials.

Of all the zany plans that came from the fertile minds on each side of World War II, few seem as out there as a plan to use birds to pilot bombs to their targets. And yet such a plan was not only actively developed, it came from the fertile mind of one of the 20th century’s most brilliant psychologists, and very nearly resulted in a fieldable weapon that would let fly the birds of war.

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