Subwoofer Vortex Cannon: 300V of “Thwup!”

Need a cool toy for your kids? How about something with a bunch of fun fluid dynamics and a tinge of higher-than-average-voltage danger? Did we mention the subwoofer and bank of high-voltage capacitors? Have we got the project for you: [Robert Hart]’s vortex cannon design.

We’ve seen vortex cannons before, where you usually fix a balloon to the back of a trash can. Pull on the balloon membrane and then let it go with a snap, and it sends out a swirling donut of high-pressure air that travels surprisingly far. It’s like smoke rings, but amped up a bit.

[Robert]’s addition is to bolt on a high-power subwoofer in place of the balloon’s rubber membrane, and generate the air pulse by dumping a capacitor bank into the speaker.

6699171432446530681The circuit design is a bit more clever than we thought at first. The bottom half is a voltage inverter followed by a diode bridge rectifier that essentially makes 320V DC (peak) out of 12V, and stores this in four fairly large capacitors. A pushbutton activates a relay that dumps the capacitors through the speaker.

On top of the circuit is a -12V voltage inverter. Just before firing, the speaker is pulled back a little bit by applying this -12V to the speaker, and then the relay is triggered and the capacitors dump, shooting the speaker cone forward.

6973681433156869012[Robert] is still developing and testing the device out, so if you’re curious or just want to say hi, head on over to Hackaday.io and do so! Be sure to check out his videos. The smoke tests are starting to look good, and we love the control box and high-voltage warning stickers.

“Giger Counter” Makes Radiation Detection Surreal

Here’s a quick question: are Geiger and Giger (as in H.R. Giger, designer of the Alien Xenomorph) pronounced the same? The answer is no. Nevertheless, the late artist has had his name mispronounced (for the record, it’s ghee-gur) by many over the years. [Steve DeGroof’s] friend posted a goofy tweet that gave him the inspiration to finally put a skeletal lid on the matter, the Giger Counter.

The innards are a Mightyohm Geiger Counter Kit. The external casing is where the true hack lies in this project, made from a 1:2 scale plastic skeleton model, flexible conduit, and dark metallic spray paint. Only the ribcage, some vertebrae, and part of the skull are used from the model. They are assembled in a delightfully inhuman fashion with some conduit wrapped around it and into the bottom of the ribcage for good measure. After some gluing and spray painting, the LED from the Geiger Counter kit is placed through a drilled hole in the skull while the board sits inside the ribcage. Getting the board in and out can be a little tricky, but it looks like the batteries can be changed without having to pull the whole board out.

Check out the video below to see the Giger Counter. If you want another hack inspired by H.R. Giger’s artistic vision, take a look at this Xenomorph suit we covered.  Or, if you can’t get enough Geiger counters, we’ve featured plenty of cool ones on this site.

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Nice Looking Countdown Timer for the Home Game Show Enthusiast

Every couple of weeks, [Roo’s] place of employment, TMW Unlimited, has a contest. This contest takes place in the form of a game show and the contestants have 30 seconds to pitch their current project to the group. A panel of judges vote on the best pitches. Winners receive cupcakes and drinks. Originally, stopwatches were used to keep track of the elapsed time, however, a stopwatch is not very game showy. [Roo] set out to make a countdown timer to add some authenticity to the bi-weekly event.

The main enclosure is a plastic fence post. Fifteen holes and 15 large LEDs are covered up by large plastic translucent spheres. End caps were designed and 3D printed to not only make the rig look good but also to serve as a speaker mount. Inside resides an Arduino that does the counting and turns off the row of lights, one every 2 seconds, as the countdown continues. A speaker not only ticks and tocks its way down with the lights, it also buzzes when time is up. Starting and resetting the timer is as easy as pushing a single button mounted on the case.

If you’ve already built a game show timer, you may want to check out this DIY game buzzer system!

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Jacquard Loom Becomes A Display

The world’s leading expert on mechanical computers wasn’t [Charles Babbage]; sure, he could design stuff, but eventually you need to actually build something. We are now graced with the expertise of [Chris Fenton]. He’s built mechanical calculators, a mechanical digital computer, and now a mechanical display inspired by the Jacquard loom.

[Chris] calls his creation the PixelWeaver, and the name isn’t far from the truth; it’s a 32-hook Jacquard style punch card reader that could be mounted over a small loom. Instead of weaving rugs and fabric, the PixelWeaver controls a 6×5 black and white display.

The PixelWeaver is built out of t-slot aluminum, 3D printed parts, and a web of thread to transfer motion from rotating cams to ratchets and pixels. The display itself is heavily inspired by a Lego mechanical display, and the cards that store the data for the display are laser-cut plywood. Interestingly, there’s nothing in this machine that couldn’t have been made 150 years ago; it’s the same technology used to weave rugs, although the necessity of a bitmap display in the Victorian era is a bit questionable.

You can see a few videos of the PixelWeaver below. If you’re wondering what else has come out of [Chris]’ mechanical computing lab, check out his digital computer and Fibonacci calculating set of gears. For a real treat, here’s a machine that will calculate all primes under 1000 in 30 years.

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Tweet-Powered Bat Removes Effort Required To Obtain Pinata Contents

A child filled game-launch event was happening in London and [Roo] was asked to use his serious making skills to construct a machine that would hit a pinata with a baseball bat. This is a great idea, well, because giving bats to a bunch of kids at a populated event probably wouldn’t end well. One of the characters from the game Skylanders is named ‘Painyatta‘ and that is whom the pinata is modeled after. Tweeting #HitPainyatta initiates a bat swing. The swing tweeter gets to keep any treats that happen to fall out.

The physical machine is pretty simple. Most of it is made of MDF and wood. A large base supports a tall, skinny box. Mounted on top is a large stepper motor with a long wooden arm holding an aluminum bat. Once a tweet came in, a moderator would check for offensive content (hey, there are kids around) using a custom Twitter API app, and if acceptable, the tweet would be displayed on an LED matrix while an Arduino controlled a stepper driver to spin the motor and swing the bat.

…no children were harmed in the making of this project…

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Levitating Objects In Paramagnetic Liquids

Two weekends ago was the Bay Area Maker Faire, and lacking a venue to talk to people who actually make things, we had a meetup at a pub. This brought out a ton of interesting people, and tons of interesting demos of what these people were building. By either proclivity or necessity, most of these demos were very blinkey. The demo [Grant McGregor] from Monterey Community College brought was not blinkey, but it was exceptionally cool. He’s levitating objects in paramagnetic liquids with permanent magnets.

Levitating objects in a paramagnetic solution around a magnetic field has been an intense area of research for the Whitesides Research Group for a few years now, with papers that demonstrate methods of measuring the density of objects in a paramagnetic solution and fixing diamagnetic objects inside a magnetic field. [Grant] is replicating this research with things that can be brought to a bar in a small metal box – vials of manganese chlorate with bits of plastic and very strong neodymium magnets. The bits of plastic in these vials usually float or sink, depending on exactly what plastic they’re made of. When the paramagnetic solution is exposed to a magnetic field, the density of the solution changes, making the bits of plastic sink or float.

It’s a bizarre effect, but [Grant] mentioned a nurd rage video that shows the effect very clearly. [Grant]’s further experiments will be to replicate the Whitesides Research Group’s experiment to fix a diamagnetic object inside a magnetic field. As for any practical uses for this effect, you might be able to differentiate between different types of plastic (think 3D printing filament) with just a vial of solution and a strong magnet.

[Grant] was heading out of the pub right when I ran into him, but he did stick around long enough to run into the alley behind the pub and record an interview/demo. You can check that out below.

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Covert Remote Protest Transmitters

As a piece of protest art, “Covert Remote Protest Transmitters” ticks all the boxes. An outdoor covert projector that displayed anti-globalization messages at a G20 summit is protest. To disguise it inside a surveillance camera body housing — sticking it to the man from inside one of his own tools — is art. And a nice hack.

However you feel about the politics of globalization (and frankly, we’re stoked to be able to get cheap tech from anywhere in the world) the open-source DIY guidebook to building the rig (PDF) makes up for it all.

They installed the camera/projector long before the summit, where it sat dormant on a wall. A cell phone inside turned on the projector’s light with each ring because they attached a relay to the cell phone’s speaker circuit. In the instructions there’s an example of using a light-dependent resistor (CdS cell) to do the same thing, relying on the phone’s backlight functionality instead. There are a lot of ways to go here.

The optics consist of a couple of lenses aligned by trial and error, then fixed in place to a balsa wood frame with hot glue. A big fat Cree LED and driver provide the photons.

The video documentation of the piece is great. It’s mostly the news media reacting to the art piece as a “security breach”. A security breach would be a gun or a bomb. This was an overhead projector displaying messages that were out of the organizers’ control. Equating security with the supression of dissent is double-plus-ungood. Touché, CRPT.

Anyway, while you’re getting prepped for your next protest, have a look at the Image Fulgurator.