Fail Of The Week: Marginally Documented Pad Shorts To Maskless PCB

October 13, 2015 by 33 Comments

[Erich Styger] was bit by a nasty gotcha when soldering a QFN surface mount chip. The problem rears its ugly head when combining a chip possessing a padless conductor and a PCB without a solder mask. As you can see in the image above, there is a conductor exiting the side of the plastic QFN, but there is no pad associated with it. For this reason, you won’t see the conductor documented in the datasheet as a pin. It is documented in the mechanical drawing of the package, without any explicit reference to its existence. This is the Jason Bourne of package quirks.

The PCB layout just happens to have a trace exiting right under this conductor. The two aren’t touching, but without solder mask, a bit of melted metal was able to mind the gap and connect the two conductors. [Eric] notes that although the non-pad isn’t documented, it’s easy to prove that it is connected to ground and was effectively pulling down the signal on that trace.

In a recent article on Hackaday I talked about “dangling pointers” and the challenge when interrupts expose the bug. [Erich’s] covered a ton of posts about embedded software. I was doing some poking around and was delighted to find that he covered the same concept and a solution for it using a program called cppcheck.

Tiny PIC Clock Is Not A Tiny Bomb

October 13, 2015 by 100 Comments

It’s been a few weeks since the incident where Ahmed Mohamed, a student, had one of his inventions mistaken for a bomb by his school and the police, despite the device clearly being a clock. We asked for submissions of all of your clock builds to show our support for Ahmed, and the latest one is the tiniest yet but still has all of the features of a full-sized clock (none of which is explosions).

[Markus]’s tiny clock uses a PIC24 which is a small yet powerful chip. The timekeeping is done on an RTCC peripheral, and the clock’s seven segment displays are temporarily lit when the user presses a button. Since the LEDs aren’t on all the time, and the PIC only consumes a few microamps on standby, the clock can go for years on a single charge of the small lithium-ion battery in the back. There’s also a phototransistor which dims the display in the dark, and a white LED which could be used as a small flashlight in a pinch. If these features and the build technique look familiar it’s because of [Markus’] tiny MSP430 clock which he was showing around last year.

Both of his tiny clocks are quite impressive for their size, features, and power consumption. Some of the other clocks we’ve featured recently include robot clocks, clocks for social good, and clocks that are not just clocks (but still won’t explode). We’re suckers for a good clock project here, so keep sending them in!

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DARE To Fly: Live Coverage Of A 50KM Rocket Launch

October 12, 2015 by 4 Comments

We wrote about the Delft Aerospace Rocket Engineering (DARE) project recently: a group of students at Delft Technical University who are trying to launch a rocket to 50kM, breaking the European amateur rocketry record. Now, the group is close to their latest launch attempt, which is scheduled to take place from their launch base in Spain between the 14th and the 20th of October.

Launch preparations are underway, with the team working through a 10,000 point pre-launch checklist. Last year, their launch failed because of a leaking valve, but the amateur engineers have just successfully completed a pressure test using inert gas, so they are confident that this problem won’t happen again. They are offering a live video feed of the launch (embedded below), and will be regularly updating their twitter feed as they prepare. We wish them the best of luck.

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Internet-Connected Box Displays Emotion, Basement Dwellers Still Unaffected

October 12, 2015 by 15 Comments

For one reason or another, Twitter has become the modern zeitgeist, chronicling the latest fashions, news, gossip, and irrelevant content that sends us spiraling towards an inevitable existential ennui. This is a Twitter mood light. It tells you what everyone else on the planet is feeling. You, of course, feel nothing. Because of the ennui.

[Connor] decided it would be a good idea to audit the world’s collective mood using experimental social analytics. He’s doing that by watching millions of tweets a day and checking them against hundreds of keywords for several emotions. These emotions are graphed in real time, placed on a server, correlated and corroborated, and downloaded by a moodLight. Inside the moodLight, the emotions are translated into colors, and displayed with the help of a few RGB LEDs.

The moodLight is currently a Kickstarter campaign, with a $30 pledge getting you an assembled board with an ATMega328, an ESP8266, a few RGB LEDs, and a laser cut enclosure. After it’s assembled, the moodLight connects automagically to the analytics server for a real-time display of the emotional state of the Twitterverse. The display is updated every second, making the backend of this build just slightly more impressive than Kickstarter itself. It’s great work from [Connor], and an interesting experiment in analyzing the state of the Internet.

Passive, But Not Innocuous

October 12, 2015 by 19 Comments

Maxim Integrated recently posted a series of application notes chronicling how there’s more going on than you’d think in even the simplest “passive” components. Nothing’s safe: capacitors, resistors, and even printed circuit boards can all behave in non-ideal ways, and that can bite you in the reflow-oven if you’re not aware of them.

You might already know that capacitors have an equivalent series resistance that limits how fast they can discharge, and an equivalent inductance that models departures from ideal behavior at higher frequencies. But did you know that ceramic capacitors can also act like voltage sources, acting piezoelectrically under physical stress?

For resistors, you’ll also have to reckon with temperature dependence as well as the same range of piezoelectric and inductance characteristics that capacitors display. Worse, resistors can display variable resistance under higher voltages, and actually produce a small amount of random noise: Johnson Noise that depends on the value of the resistance.

Finally, the third article in the series tackles the PCB, summarizing a lot of potential manufacturing defects to look out for, as well as covering the parasitic capacitance, leakage currents, and frequency dependence that the actual fiberglass layers themselves can introduce into your circuit.

If you’re having a feeling of déjà-vu, the same series of articles ran in 2013 in Electronic Design but they’re good enough that we hope you won’t mind the redundant repetition all over again. And if you’re already quibbling with exactly what they mean by “passive”, we feel your pain: they’re really talking about parasitic effects, but we’ll let that slide too. We’re in a giving mood today.

[via Dangerous Prototypes]

Quick And Easy Thermic Lance Is Hot Enough To Melt Rocks

October 12, 2015 by 42 Comments

Heat can be a hacker’s best friend. A little heat can help release a stubborn nut cleanly, and a lot of heat can melt a rusty bolt clean off. An oxy-acetylene torch is handy for these applications, but if you need a more portable setup, and you want enough heat to melt rocks, you might want to look into this field-expedient thermic lance.

Thermic lances have been around a long time in the demolition industry, where cutting steel quickly is a common chore. Commercial thermic lances are just a bundle of steel fuel rods which are set on fire while oxygen is blown down a consumable outer tube. The resulting flame can reach up to 4500°C with impressive results. In need of a similarly destructive device, [NightHawkInLight] came up with a super-simple lance – a small disposable tank of oxygen and regulator, a length of Tygon tubing, and a piece of 5/8″ steel brake line. No need for fuel rods in this design; the brake line provides both fuel and oxygen containment. As you can see in the video below, lighting the little lance without the usual oxy-acetylene torch is no problem – a “wick” of twisted steel wool is all that’s needed to get the torch going. The results are pretty impressive on both steel and rock.

You say you’re fresh out of brake line and still need some “don’t try this at home” action? No problem at all – just hit up the pantry for the materials needed for this tinfoil and spaghetti thermic lance.

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CyberPunk Yourself – Body Modification, Augmentation, And Grinders

October 12, 2015 by 116 Comments

“We accept pain as a price of doing business, even if it is just for aesthetic purposes. You want to put a magnet in your finger, a doctor will ask you why; a mod artist will ask when you can start.” As with many other people who are part of the growing grinder movement, [Adam] has taken a step that many would consider extreme – he’s begun to augment his body.

Grinders – men and women who hack their own bodies – are pushing the boundaries of what is currently possible when it comes to human augmentation. They’re hackers at heart, pursuing on an amateur level what they can’t get from the consumer market. Human augmentation is a concept that is featured heavily in science fiction and futurism, but the assumption most people have is that those kinds of advancements will come from medical or technology companies.

Instead, we’re seeing augmentation begin in the basements of hackers and in the back rooms of piercing studios. The domain of grinders is the space where body modification and hacking meet. It mixes the same willingness to modify one’s body that is common among the tattooed and pierced, and adds an interest in hacking technology that you find in hackerspaces around the world. When those two qualities intersect, you have a potential grinder.

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