BAMF: Hard Drive Platter Launcher Among All-Time Favorites

The hard drive platter launcher that [Krux] built has been among my all-time favorite builds and I am so excited that he is showing it off at this year’s Bay Area Maker Faire. At its core the concept is quite simple; dump a large amount of current through a coil all at once, and the magnetic current generated spontaneously repels the aluminum hard drive platter. The devil is in the details and this is where [Krux’s] work really shines.

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Box ‘o Bangs, A 2,180J Capacitor Bank

What happens when you wire up 16 capacitors? Sixteen 2500V 40uF capacitors to be precise… [Lemming] calls it the Box ‘O Bangs. Theoretically it outputs 4000A at 2500V for a split second.

They bought the capacitors off of eBay, and they appear to be good quality BOSCH ones, straight from Germany. They were apparently used for large-scale industrial photo-flashes, but who knows since they’re from eBay.

Soldering it all together proved to be a challenge, as once they realized just how many amps this thing was going to put out, they needed some thick wire. It looks like about 2ga wire, which, spoiler alert, still isn’t enough for 4000A — but since it’s only for a split second it seems to do fine.

Once everything was built, it was time for some scientific tests — what can we put between the leads to explode? Stay tuned for some slow-motion glory.

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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 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.