DO NOT Build A Fully Automatic Battery-launching Air Gun

November 7, 2011 by 177 Comments

There’s nothing quite like [Elliot]’s cherubic sense of wonder and maniacal laughter after he tests his fully automatic AA battery-launching air gun. That fires 600 rounds a minute. At 200 feet per second.

We need to take a minute and say [Elliot]’s gun is stupidly unsafe. He used PVC pipe to hold air pressure, so that may… explode one of these days. Also, the AA batteries coming out of the end of the barrel have the same kinetic energy as a .22 rifle bullet.

The mechanics of the gun is a simple blow forward bolt. When he pulls the trigger, the bolt – and battery – are forced forward due to air pressure. After the bolt has cleared a plug, air is allowed to flow through the bolt pushing the battery along with it. Once the pressure in the barrel is back down to normal, a spring forces the bolt back into place and the 23 round magazine loads another battery. Simple, really. [Elliot] posted some pics of his gun on the spudfiles.com forum.

The gun is accurate to about 100 yards. It’s a very impressive piece of engineering for a bit of PVC pipe, but we don’t feel the need to copy this one. Check out the videos after the break to see this thing in action.

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Google Hangout Laser Turret

November 7, 2011 by 13 Comments

The guys from the House4Hack hackerspace in Johannesburg won the 2011 Google+ Hackathon with their Friggin’ Laser Turret. The build started off as a remote-controlled webcam that can be controlled by anyone in a Google+ hangout. On a whim, the team decided to add a laser to the build because lasers are awesome.

The inspiration for the build was to have a Google+ hangout available whenever someone is at the hackerspace. If a guest can’t grace the team with their physical presence, at least they can be there virtually. The camera is controlled by an Arduino running a bog-standard servo library implementation. The Arduino is connected to a laptop over a serial connection and is able to move left and right. To spice things up a little, the team added a 25mA laser diode to the build controlled from a digital output on the Arduino.

For winning the Jo’burg Google+ Hackathon, the guys scored themselves a Samsung Galaxy S II phone. Not a bad prize for building something cool. Check out the demo of the friggin’ laser turret after the break.

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Wireless MIDI Piano Glove

November 7, 2011 by 9 Comments

Sometimes you just don’t have space for a baby grand. [Abdullah] got around this problem and built a virtual wireless MIDI piano. Unlike it’s inspiration, it’s not bad but we still love it.

[Abdullah] got his hands on some flex sensors and attached them to a glove. These resistive sensors are put through a voltage divider and sent to a microcontroller (a PIC16F778, we believe) and corresponding MIDI notes are chosen. These MIDI notes are sent to a computer and played over a speaker.

Right now, only a single arpeggio is coded into the microcontroller. Depending on which finger is bent shifts this arpeggio up and down the keyboard. That being said, the firmware can be easily modified to recognize standard piano fingering so chords can be played. The only issue is moving the hand up and down the keyboard.

[Abdullah] is planning on making his glove completely wireless with a microcontroller and battery sewn into the glove. Here’s to hoping he’ll keep us posted.

Check out [Abdullah]’s demo after the break.

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magic-wand

Hacking A “magic Wand” To Remotely Control Light Displays

November 7, 2011 by 12 Comments

Hackaday reader [Kieran] volunteers at an outdoor haunted house attraction called the “Disenchanted Forest”. Attendees are lead through the haunted forest by a volunteer, who helps keep everyone on the predetermined trail. The trail is usually lit by small LED fixtures that the group constructed, but the organizers wanted to make the lights more interactive this time around.

A fellow organizer gave [Kieran] a [Harry Potter] Magic Candle, which allows him to light the toy with the wave of his IR-enabled wand. He was told to “make it do something cool”, so he took a closer look at it to determine how everything worked.

Using an Arduino clone and some borrowed IR code he was able to get the wand to work with the forest’s trail lighting, but there was a lot of lag between waving the wand and triggering the light. Taking a second stab at it, [Kieran] was able to replicate the IR protocol used by the toy, speeding things up and increasing the wand’s range considerably. Now, the tour guides can light and extinguish the trail lighting with a simple flick of the wrist.

Take a look at the video below to see how things worked out for [Kieran], and be sure to swing by his site for more details if you have the urge to modify your Magic Candle.

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Canon FD Lenses On An EOS Mount

November 6, 2011 by 19 Comments

Camera lenses are expensive and if you’re like us, you can easily find really cheap lenses that your camera can’t use. [Sam] has a Canon EOS and a bunch of old-school FD lenses at his disposal. There’s one problem though: using these old lenses with an adapter means focusing at infinity is out of the question. Thankfully, he put up a few videos (part 1, part 2, and part 3) walking through the process of modifying an FD lens for his new camera.

To do the modification for the FD lens, all that’s needed is some epoxy, a screw driver, and an M42 to EF adapter. After disassembling the back of the FD lens, [Sam] mounted the M42 adapter on his camera and held the lens up to check the minimum focusing distance. A bit of grinding or a few metal shims ensure that the lens is in the right position.

The next step is making sure the aperture can still be controlled. [Sam] goes through this in part two of his video. A little bit of dremeling takes care of all the hard work. The lens is finally attached to the M42 adapter with a tiny bit of epoxy, and the conversion is complete.

While [Sam] could have put up a few close up pics of his build, he goes through every step of the process very well. Check out the embedded videos after the break.

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DIY Spot Welder Can Join Anything Together, Even Copper

November 6, 2011 by 35 Comments

copper-spot-welder

Hackaday reader [David] was looking for a cheap and easy way to spot weld copper tabs together. As he notes in his writeup, the properties of copper which are most enticing, such as high thermal capacity, make welding it all that more difficult. His home-brew method of spot welding is admittedly quick and dirty, but it does get the job done quite well.

He started off with an array of four 2.5V @ 2600 Farad ultra capacitors, which provide the high current required to do copper spot welding properly. They are wired in series and connected to his electrodes using heavy gauge wire. The graphite-tipped electrodes were an interesting DIY job themselves, cleverly constructed using copper tubing and a graphite block. The most simple/dangerous/clever part of the whole rig is his trigger mechanism, which consists of a pair of copper blocks that he bangs together manually to complete the circuit.

[David] is well aware that the setup is just a touch rough, but according to him it makes great welds, and it’s only a proof of concept at this point. He has a hefty list of improvements to make for the final version, including a different switching method among a few other safety precautions.

4Track Robot Gets Around With Ease

November 6, 2011 by 8 Comments

4track-robot

[Jon] has been developing a slick little RC robot in bits and pieces over the last year or so, which can constructed by anyone with access to a 3D printer. Servos and electronics aside, the entire thing can be put together in short order using the plans he posted on Thingiverse.

The robot makes use of four “caterpillar” type bots, which are all connected via a central frame. Once [Jon] had the general design for a single caterpillar bot down, he moved forward to create the robot you see above. His friend [Julián] lent a hand in the form of electronics and code, which allows the robot to be driven using a standard USB gamepad.

As you can see in the video below, the robot gets around nicely, climbing over obstacles with relative ease. While it is a bit loud, [Jon] says that’s due to the undersized servos they happen to be using at the moment. We think it looks great so far, but [Jon] already has plans to beef up the motors and add wireless control in the near future – we can’t wait to see it then!

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