When Airsoft gets boring, build a coil gun!


Here at Hackaday, we’re all about repurposing old items you no longer use. Reader [Liquider] wrote in to share his latest creation, a coil gun built from an old Airsoft pistol.

He removed a handful of components from the pistol and installed a 800 uF/300V capacitor inside the grip. A small storage compartment was added under the barrel, which houses the AA battery he uses to drive the circuit. A modified reloading mechanism makes it easy to drop a metal projectile right in front of the coil before firing.

Once the pistol is charged up, a switch installed behind the trigger discharges the cap, creating a magnetic pulse that accelerates the metal projectile forward. [Liquider] estimates that the kinetic energy produced by the coil is 0.1 Joules, which fires of the slug at a reasonable speed.

Continue reading to see a quick video demo of the pistol in action.

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Zigbee home automation gives us another reason not to get up

[Russell] sent in a neat home automation project he’s been working on. Even though the project only has two devices so far, we can already see the potential of his project.

Instead of the X10 standard that has been a staple of home automation for more than 30 years, [Russell] went with ZigBee modules. Aside from being much faster and more flexible than X10 home automation modules, ZigBees also open up a bunch of projects that would be impossible if he went with X10. With some well-placed IR transmitters hidden in his living room, it would be possible to have a TV and cable box controlled via the Internet.

So far, [Russell] built an network-controlled RGB ‘mood lamp’ and an infrared remote for his central air. Everything is controlled through a web app, and [Russell] says that additional modules can be easily added to the code.

Check out [Russell]‘s demo of his project after the break.

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More FrankenKindle progress

[Glenn] sent us an update on his FrankenKindle project. You might remember this hack from back in July. [Glenn] is modding the device to make it easier for his sister, who has Cerebral Palsy, to use.

The latest revision adds a case for the hardware. The silver button pad is what remains of the V.Reader (a children’s toy), having had the screen portion hacked off. The case provides a stable base for the reader and buttons, holding them at a nice angle for easy use. There’s just a bit of cable routing that needs to be finished to protect some fragile connections. The picture above does show the circuit board to the side, but there is a place for it around back.

In the video after the break [Glenn] mentions that the response to keypresses is a little sluggish. Sure, some of this is Kindle’s own delay when refreshing the ePaper display. But we can’t help but think the code running on the Teensy could also be optimized. We’ve asked him to post his code if he wants some tips, so check back and help out if you can.

We do have one feature suggestion for him. The Kindle keyboard no longer functions because that flat cable coming out the side is what connects to it. It’s quite easy to add a PS/2 keyboard port to a microcontroller. That would be a nice addition to the FrankenKindle as it would make things like shopping for books a bit easier.

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Cellphone controlled retro-radio stores and plays your digital library

[Autuin] was worried about having desirable electronics stolen while on the road with his band. He didn’t want to take a laptop along on tour, but he didn’t want to be without his music either. To solve this problem, he built a music player inside of a cheap-looking radio. His write-up covers two different portable MP3 solutions, but it’s the second rendition that catches our attention.

After hollowing out the old radio he filled the void with an Asus WL-HDD 2.5. That hardware is meant to be an easy way to add network storage; it houses a laptop hard drive and has WiFi and Ethernet connectivity. But it also has one USB port, and can be hacked to add a second. [Autuin] did just that, using the two USB connections to add a Bluetooth dongle and a USB sound card. Music is synced with the hard drive via some cat-5 cable that’s hidden in the battery compartment of the vintage box. The NAS runs Linux, and the audio playback software is controlled though a Mobile Java application running on a somewhat broken cellphone. That’s an idea that might find its way into our next project.

Water-powered multi-channel audio

[Niklas Roy] is rolling out some water-powered music for Berlin’s Museum night. It seems that this water-wheel is attached to the side of the Museum. It’s got a stream flowing past it and the wheel is constantly turning. The thing is, that work isn’t being used for anything. Now we’ve already seen [Niklas] making electricity from moving water, but that’s far from what he had in mind this time around. Instead he’s driving a multitude of music boxes with the motion transferred from the water.

He teamed up with another artist named [La belle Imira] to build and connect a series of pulleys to the waterwheel. The video after the break shows the rope system being strung throughout the grounds of the museum. After passing around the output drum of the water wheel, the rope snakes through each pulley. Many of the pulleys have the mechanism from a music box attached to their axles, so whenever the water is flowing, music plays. They don’t all play the same tune, so you get a variety of selections as you walk around. We could swear that one of them is playing ‘My Way’.

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The Dish-o-Tron 6000 is back and better than ever


When designing a circuit on the bench, sometimes things work far better than they do in real life. [Quinn Dunki] learned this lesson over the last few months as she struggled with one of her recent creations, the Dish-o-Tron 6000. We featured the Dish-o-Tron back in April, and at that point things seemed to be working out well for [Quinn]. As time passed however, she found the device to be an unreliable power hog. Aside from eating through a battery every few weeks, it kept spontaneously switching states from ‘Dirty’ to ‘Clean’ and back. It was time to take the Dish-o-Tron back to the bench for some debugging.

The random status flip from ‘Dirty’ to ‘Clean’ was a relatively easy fix, and required a small capacitor between the set pin and ground to eliminate the electrical noise that was tripping things up. She nailed down the spontaneous ‘Clean’ to ‘Dirty’ flip to a stuck tilt switch, which she swapped out for a mercury-based model, making things far more reliable. She solved her battery problems by wiring in a 12v wall wart, which might not be any more energy efficient, but it does save her from swapping out batteries all the time.

It’s always nice to see how projects evolve over time, and how the inevitable bugs are worked out of an initial design.

Forget that boring old fire pit, build a Flame Tree instead!


Maker Faire is a great event to attend not only because you get to see all sorts of cool designs and machinations, but because you can participate as well. At Maker Faire Bay Area 2011, maker [Brett Levine] put together a fun and interactive display he likes to call the DIY Flame Tree.

The concept is pretty simple, and he says everyone who participated got a pretty good kick out of lending a hand. Each participant was given a piece of copper tubing and allowed to bend, twist, and sculpt it to their liking before using a drill to add holes wherever they pleased. They were then allowed to choose where their portion of the project would be mounted on the existing tree.

With everyone standing a safe distance away from the display, [Brett] pumped it full of propane and lit the various sections on fire. In the video below, you can see that the display was blown around a bit by the wind, but we imagine it would look pretty awesome on a still summer evening.

Even if you’re not into this sort of art, you have to admit that it certainly beats a boring old fire pit!

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