Coke-Propane Rocket Blasts Off Without Ignition

Everyone’s seen the Diet Coke and Mentos “experiment” that ends in a brown eruption. But have you seen the Coke and Propane experiment insanity that results in a rocket launch? As [Itay] pointed out when he sent us the tip, this doesn’t need to be lit. The simple act of turning the bottle upside down starts a powerful reaction without any ignition.

coke-propane-rocket-thumbOf course it’s the how of this that tickles our brains, but let’s finish the setup. This starts with a bottle of Coke which is about 3/4 full. The head space is displaced by spraying propane into the bottle; propane is heavier than air. All that’s left is to turn the bottle upside down and pray it doesn’t smack anyone in the noggin as it takes off.

In trying to find an explanation for this phenomenon we came across a plausible answer on the Chemistry StackExchange. It points to the Mentos phenomenon combined with the temperature differential caused by the very cold propane. The answering user theorizes that tiny ice crystals form and when the bottle is turned upside down the cold propane and micro crystals rise through the warmer soda acting as a much more rapid catalyst than Mentos alone. Of course this is just a theory so please share your own ideas below.

We thought the folks who microwave stuff outside of a microwave enclosure had their fill of danger but this videos is also one of theirs. It should be no surprise that they also tried the experiment with an ignition source. That video is found after the break and should immediately convince you to never try any of this yourself.

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FPGAs For The Raspberry Pi

FPGA development has advanced dramatically in the last year, and this is entirely due to an open-source toolchain for Lattice’s iCE40 FPGA. Last spring, the bitstream for this FPGA was reverse engineered and a toolchain made available for anything that can run Linux, including a Raspberry Pi. [Dave] from Xess thought it was high time for a Raspberry Pi FPGA board. With the help of this open-source toolchain, he can program this FPGA board right on the Raspberry Pi.

The inspiration for [Dave]’s board came from the XuLA and StickIt! boards that give the Raspberry Pi an FPGA hat. These boards had a problem; the Xilinx bitstreams had to be compiled on a ‘real’ PC and brought over to the Raspberry Pi world. The new project – the CAT Board – brings an entire FPGA dev kit over to the Raspberry Pi.

The hardware for the CAT Board is a Lattice iCE-HX8K, 32 MBytes of SDRAM, a serial configuration flash, LEDs, buttons, DIP switches, grove connectors, and SATA connectors (although [Dave] is just using these for differential signals; he doesn’t know if he can get SATA hard drives to work with this board).

Despite some problems with his board house, [Dave] eventually got his FPGA working, or at least the bitstream configuration part, and he can blink a pair of LEDs with a Raspberry Pi and programmable logic. The Hello World for this project is done, and now the only limit is how many gates are on this FPGA.

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Guinea pig power

Guinea Pig Methane Power!

Half-way around the world, a couple in Peru is harnessing the power of guinea pig poop, to generate methane for their farm. We couldn’t make that up if we tried.

The couple are a pair of retired plant physiology professors who have taken to running a sustainable agriculture program in their very own villa called Casa Blanca. It’s a beautiful set of gardens complete with a lab for research. But the most curious thing is the thousand guinea pigs they raise. They have a special shed for them with small compartments separated by brickwork. The guinea pigs eat specialized plant waste, and in turn, produce an astonishing 3 tonnes of fecal matter per month.

They use around 200kg of the excrement to power their very own bio-digester which in turn produces 3 cubic meters of methane per day which they use for powering their villa. The rest of it is used for fertilizer that they sell to local farms.

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C++ Turns 30 – Looking Forward To The Future

[Bjarne Stroustrup] introduced C++ to the world on Monday 14th October 1985 at the ACM annual conference on “The Range of Computing”. On its 30th anniversary [Bjarne] reviewed the history, his experience, and his thoughts on the future of the language in an interview. Also on that day the first edition of his book, “The C++ Programming Language” was released. It’s now available in a 4th edition. The title differed only in the “++” from the classic C book by [Kernighan] and [Ritchie] that graced the desktops of a multitude of C programmers.

The first versic++ bjarneons of C++ were compiled with CFront, a compiler that generated C code which was then compiled as normal. Around the 1990s, it’s unclear when, numerous native compilers became available, notably for PCs, which lead to explosive growth from 400,000 users to an estimated 4.4 million today.

 

One of the frustrations [Stroustrup] expresses is how C++ is viewed by developers,

… a problem that has plagued C++ forever: Poor teaching and poor understanding of C++ even among its practitioners. There has always been a tendency to describe C++ as some odd variant of something else.

Soon the standards committee is meeting to discuss C++17 in Hawaii. Fair winds and bright skies look to be in the future of C++.

LED Pendulum Pulses Out Clock Face

You have to admit [Dylan Rush’s] clock is a real swinger. Literally. You’ve seen the desk novelties where an arm with leds mounted on it sweeps out a message? [Dylan] did the same thing to make a clock but instead of drawing numbers, he actually draws an analog clock face. Y’know one of those round things with arms?

IMG_20150824_2156213_rewindBehind the clock is an Arduino driving a MAX7219 LED controller. Using the MAX7219 was a challenge because it expects a grid of LEDs while the clock needs a linear array. [Dylan] used a line of individual LEDs wired to match what the controller wanted. A rotary encoder tells the processor the position of the arm so the Arduino sketch can determine which LEDs should be lit to show the time and clock face.

What’s even more amazing is [Dylan] created this before clocks became infamous.

Swing over to the video after the break.

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RF Attack Controls Nearby Smartphones Via “Okay Google” And “Hey Siri”

Screenshot_20151016-170014Most spy movies (at least the ones worth their salt) will include a few scenes that depict nerds in a van listening in on conversations remotely and causing the victims phones to do things like turn themselves or their cameras on. We have been made to believe that it takes an entire van of equipment and one or two MIT level hackers to pull this off. Turns out all it takes is about $2300, some know how, and an unsuspecting target with a set of microphone-equipped headphones attached to their phone.

The French Government’s information security research group ANSSI has been investigating this and published a paper with their findings. Unfortunately that paper is behind a paywall. Wired has a pretty good summation of the findings, which use a transmitter to induce a current in the headphone wires. This in itself isn’t surprising. But they’re able to do it with such accuracy that it can both trigger, and successfully interact with the hands-free features provided by Siri and Google Now.

We think this is a really cool proof-of-concept. It’s mentioned that an attacker could potentially use this to make calls or do other things that cost the victim money. We think it’s more likely to be implemented by resourceful young engineers as a practical joke. Rick Rolling is a poplar go-to. But if you can make the phone “hear” audio, you should also be able to make someone wearing headphones hear ghosts. This has a lot of potential. The first one to make this happen really needs to let us know about it.

 

3D Printed Gun Is Off The Rails

There are certain topics that cause people to have knee-jerk reactions: Try asking a crowd which Star Trek was best or–around here–take a stance for or against the Arduino and you’ll see what we mean. Certainly people polarize quickly when you talk about a 3D printed gun. However, if anyone can sneak [xtamared’s] 3D printed rail gun through airport security, then some guards will have to be fired. It looks like a cool prop from a bad movie, but (as you can see in the videos below) it can project a conductive slug into a decidedly low-tech target.

There aren’t many build details, although you can deduce a few things from the pictures and the captions. At the rear of the gun is a paintball tank that gets the slug moving before it hits the rails which further accelerate the projectile. The electric part is Arduino-based and the very prominent capacitors at the front end can deliver 1800 joules of energy (and add 20 pounds of weight to the gun).

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