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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WiFi Fob Acquaints OLED With ESP

When you think of WiFi in projects it’s easy to get into the rut of assuming the goal is to add WiFi to something. This particular build actually brings WiFi awareness to you, in terms of sniffing what’s going on with the signals around you and displaying them for instant feedback.

[0miker0] is working on the project as his entry in the Square Inch Project. It’s an adapter board that has a footprint for the 2×4 pin header of an ESP8266-01 module, and hosts the components and solder pads for a 128×64 OLED display. These are becoming rather ubiquitous and it’s not hard to figure out why. They’re relatively inexpensive, low-power, high-contrast, and require very few support components. From the schematic in the GitHub Repo it looks like 5 resistors and 7 caps.

The video below shows off two firmware modes so far. The first is an AP scan that reads out some information, the second is a weather-display program. Anyone who’s worked with the ESP modules knows that they have the potential to gather all kinds of data about WiFi signals — one of our favorite demos of this is when [cnlohr] used it to create a 3d light painted map of his WiFi signal strength. Chuck a rechargeable LiPo on this thing, tweak the example code for your needs, and you have a new gadget for wardriving-nouveau.

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Random Parcel Launches Steganographic Compulsion

A mysterious CD arrives in the mail with a weird handwritten code on it. What should you do? Put it in the computer and play the thing, of course!

Some might be screaming at their screens right now… this is how modern horror films start and before you know it the undead are lurking behind you waiting to strike. Seasonal thrills aside, this is turning into an involved community effort to solve the puzzle. [Johny] published the video and posted a thread on reddit.

We ran a similar augmented reality game to launch the 2014 Hackaday Prize solved by a dedicated group of hackers. It’s really hard to design puzzles that won’t be immediately solved but can eventually be solved with technology and a few mental leaps. When we come across one of these extremely clever puzzles, we take note.

This has all the hallmarks of a good time. The audio spectrogram shows hidden data embedded in the file — a technique known as steganography. There are some real contortions to make meaning from this. When you’re looking for a solution any little hit of a pattern feels like you’ve found something. But searching for the decrypted string yields a YouTube video with the same name; we wonder if they’ve tried to recover steganographic data from that source?

[Johny] mentions that this parcel was unsolicited and that people have suggested it’s a threat or something non-sensical in its entirety. We’re hoping it’s a publicity stunt and we’re all disappointed in the end, because solving the thing is the best part and publicity wouldn’t work if there was no solution.

The bright minds of the Hackaday community should be the ones who actually solve this. So get to work and let us know what you figure out!

SuperCon Presenters Revealed

When we announced the Hackaday SuperConference earlier this week we weren’t able to mention any presenters; the call for proposals to this epic hardware conference was still open. Now that the proposals are in we have been poring over them and starting to send acceptance notifications. Just a few of the notable presenters who have already confirmed are listed below. This is more than enough to get the excitement started but we will of course announce more in the coming days.

Check out the amazing space we’ve booked at Dogpatch Studios. It is perfect for the non-stop, high-throughput schedule that has been assembled. There will be one speaking track for talks that spans the entire weekend, while multiple concurrent workshops are held on the other floor of the venue. The evening party will kick off with the announcement of the 2015 Hackaday Prize winner, and the winner of Best Product.

Head over and apply now to attend the two-day SuperCon in San Francisco on November 14th and 15th. This list of amazing people and topics is just a taste of over thirty talks and workshops going on at the hardware conference you’ve been waiting for.

Shanni R. Prutchi  | Construction of an Entangled Photon Source for Experimenting with Quantum Technologies

Sprite_TM | Implementing the Tamagotchi Singularity

Michael Ossmann | Simple RF Circuit Design Workshop

Fran Blanche | Fun and Relevance of Antiquated Technology

Paul Stoffregen | Advanced Microcontroller-Based Audio Workshop

Noah Feehan | Making in Public

Sarah Petkus | NoodleFeet: Building a Robot as Art

Minas Liarokapis | OpenBionics

Luke Iseman | Starting a Hardware Startup

Dozens more to come.


Download the SuperCon poster and hang it everywhere. Share the @hackaday #SuperCon.  Do it now.

Thor’s Hammer Build Recognizes Its Master’s Hand

electromagnetic-thors-hammerOnly those who have completely insulated themselves from modern pop culture will miss the meaning of a Mjolnir build. It is, of course, the mythical hammer wielded by Thor, and only Thor. It’s a question of being worthy; a question solved perfectly by this electromagnetic Mjolnir build.

Using an electromagnet is smart, right? Just plunk the thing down on something metal (that is itself super-heavy or well-anchored) and nobody will be able to pick it up. It starts to get more interesting when you add a fingerprint reader, allowing only Mjolnir’s Master to retrieve it from atop a manhole cover.

But for us the real genius in the build is that the hammer isn’t burning power from the four 12V batteries most of the time. All of the people in the video below could have picked up the hammer had they first nudged it off the metal plate with their foot. The build uses a capacitive touch-sensor to enable and disable the microwave over transformer used as the electromagnet. An engineering trick like this really separates the gods from the posers.

We hate to admit it, but this is probably a cooler build than the Telsa-Coil powered Mjolin that [Caleb] built a few years back. Still, his held up as the best for many years, and if you’re going to be displaced this really is a build worthy of the new title: coolest Mjolnir hack.

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Kids Explore Engineering With Cartoon Tech Build

“To the Tortuga!” my husband and I heard the announcement from the backyard. Our two boys, Ben (7) and Miles (3), had become pleasantly obsessed with the coolest brothers in nature – the Kratt Brothers. From the moment that these two energetic animal-loving brothers were discovered by our kids, they’ve been huge fans. Our house has been transported to the Sonora Desert where we saved a Gila Monster, then to the Australian Outback to learn about the Thorny Devil. We even went to swing with the Spider Monkeys in South America and then back to the good ‘ole U.S. of A to harness the speed of the Roadrunner – since we are, after all, a family of runners!

creaturepod-from-show
Creaturepod [Source: WildKratts Wiki]
Our boys have been the Grand Brothers for months and there are no signs of it letting up. At the end of summer, I decided to reward the kids with a Creaturepod, a plastic toy meant to look like the fictional walkie talkie of the same name used on PBS Kids’ Wild Kratts program. They loved it, but soon found that it didn’t do anything on its own. They both have wild imaginations and like to bring to life most of their play, but the toy just wasn’t doing it for them. Being that Chris and Martin Kratt are brothers in real life, and Ben and Miles Grand are brothers in real life, Ben thought it would only be right to have “real life” Creaturepods. Real walkie talkies that he could use to communicate with his friends and have Wild Kratts adventures. This natural interest provided an opportunity to make learning, designing, and building a source of fun for the boys. It is an amazing way to teach that you can change the world around you by having an idea, making a plan, and gathering everyone with the skills needed to complete the project.

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Hand-Cranked Cyclotron

Okay, not actually a cyclotron… but this ball cyclotron is a good model for what a cyclotron does and the concepts behind it feel kooky and magical. A pair of Ping Pong balls scream around a glass bowl thanks the repulsive forces of static electricity.

It’s no surprise that this comes from Rimstar, a source we’ve grown to equate with enthralling home lab experiments like the Ion Wind powered Star Trek Enterprise. Those following closely will know that most of [Steven Dufresne’s] experiments involve high voltage and this one is no different. The same Wimshurst Machine he used in the Tea Laser demo is brought in again for this one.

A glass bowl is used for its shape and properties as an insulator. A set of electrodes are added in the form of aluminum strips. These are given opposite charges using the Wimshurst machine. Ping Pong balls coated in conductive paint are light enough to be moved by the static fields, and a good crank gets them travelling in a very fast circuit around the bowl.

When you move a crank the thought of being connected to something with a chain pops into your mind. This feels very much the same, but there is no intuitive connection between the movement of the balls and your hand on the crank. Anyone need a prop for their Halloween party?

If you don’t want to buy or build a Wimshurst machine you can use a Van De Graaff generator. Can anyone suggest other HV sources that would work well here?

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