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.

19 thoughts on “Subwoofer Vortex Cannon: 300V Of “Thwup!”

  1. Very cool. When I was a kid Mattel or someone made the “Sonic Air Blaster”. There was a handheld and a shoulder bazooka style. A big lever cocked the hand held by pulling back a rubber diaphragm. They were not silent, but they didn’t sound like they were going to blow your hat off from 20 feet. Here is Kurt Russel demonstrating https://www.youtube.com/watch?v=El6t8lcz0V4 I can’t find the hand held one. Maybe the rubber diaphragms are all shot.

    1. In the add, Kurt Russel is aiming the “Air blaster” along a busy highway. What would happen to a kid doing that today? Favorite Kurt Russel movie: Escape from New York 1981, (even worse that the Tina Turner Mad Max movie).

    1. A side effect of using a relay is its delay which in this case is useful: when shoot button is pressed the woofer is supplied with -12V which moves backwards the cone. As soon as the relay closes (which is not instantaneous) the woofer sees the full positive voltage and moves forward. In other words, it “charges itself” with a bit more air just before firing. Brilliant!

  2. “Where there’s smoke there’s fire”, but in this case there’s “fire” but no smoke. An invisible vortex isn’t much fun. What happens if you fire this in a room that’s been filled with fog or smoke? (Especially if you have clear air in the cannon and uncover it just before firing). Do you get an inverse vortex? I’d also like to try firing it into a mist of water coming from a garden hose, especially in bright sunlight. And I’d REALLY like to try firing it at the annoying dogs next door–nonlethal dog repellent! (Hmm… Maybe I’ll fill it with a cloud of chili flakes.) Hang one over my flower bed with a motion sensor and scare away pesky rabbits and squirrels. Endless possibilities for weaponizing!

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.