Hackaday Links: April 25, 2011

April 25, 2011 by Mike Szczys 45 Comments

iPad2 combination case

[Jasn] wasn’t happy with Apple’s version of the iPad2 case, but an InCase Magazine Jacket didn’t meet his needs either. He broke the two apart and combined pieces of each to achieve his perfect tablet enclosure.

MIDI power tools

Enjoy the sounds of working in the shop thanks to [ArcAttack’s] MIDI controlled power tool performance. Our favorite part’s the outlet box stuffed with cords. [Thanks Ross]

Labeling cables

When we saw [László’s] tip about labeling cables we though “duh, we’ve been doing that for years”. But then we realized to this technique might be new to some folks. So haters gonna hate, but get out some tape and a marker to make your cord mess a bit more tidy.

The folks that run Facebook set out to build their own server farms in order to save money on both materials and electricity. They’ve open sourced the hardware and there’s a bunch of information about the project that we found interesting. [Thanks Wouter]

Manual mute ‘key’ for your netbook

[Randi] wanted a way to ensure he wouldn’t have startup sounds played in class when he booted up his netbook. He came up with this ‘mute key’ that is made from a ground-down headphone plug. He glued a piece of ribbon to it so that it can be removed again. The computer thinks there’s headphone plugged in so no sound plays through the speakers. Since it’s been ground down it’s extra-low-profile, and it’s as cheap as your last broken set of headphones. No link here, [Randi] just emailed us some pictures.

Single-chip Digital Audio Player

April 25, 2011 by Mike Szczys 48 Comments

[Dmitry Gr.] built a simple circuit to playback digital audio. At the center you can see an 8-pin PIC 12F1840 microcontroller. It’s pulling audio data from a microSD card which is read through a full-sized SD card adapter to which he soldered jumper wires for all of the necessary connections. There is one additional semiconductor, a FET which is used to drive the speaker seen to the left. Unregulated power is provided by a pair of AA batteries (four are seen in the picture above but only two are actually connected to the circuit). He’s planning to post his code package soon, but for now you’ll have to be satisfied with a couple of demo videos and a schematic. Both videos are embedded after the break, and we’ve also included a screenshot of the schematic which is shown in the second video.

This is very similar to the 1-Bit Symphony CD we saw almost a year ago in a links post. That one used a jewel case instead of the protoboard seen here, and had a headphone jack instead of the speaker.

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Motorcycle Turned Chicken Launcher

April 25, 2011 by Mike Szczys 19 Comments

Those who frequently work with them will tell you that rubber chickens are actually pretty heavy. You’re not going to do much damage chucking them by hand and that’s why you need your own rubber chicken launcher. This most-excellent magazine-fed foul-flinger was built by artist [Sean Pace] as a senior project while working toward his fine arts degree at UNC Asheville. He reused the rear end of a motorcycle, purposing the spinning wheel to grab the birds out of an in-feed channel and fling them much like a mechanical football launcher would. It kind of makes us wonder if you could do the same thing with a pneumatic football launcher?

[Sean’s] contraption is built on a stationary base, but in the video after the break you can see it firing from a flatbed truck. Seems somewhat like a whimsical warthog if you’re a Halo fan.

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Nerf Mind Bullets

April 22, 2011 by Mike Szczys 9 Comments

[Chris] thinks that using your brain to control your trigger finger is a passé way of operating a toy firearm. Instead, he’s using his mind to fire foam bullets at whatever he thinks needs to pretend-die. To read his will, he’s chosen the Neurosky MindWave, a device that we just looked at for servo control. That hack shows how to patch into the USB dongle that comes with the device, but [Chris] opted to use a BlueSMiRF module from Sparkfun to connect the headset to an Arduino via Bluetooth.

The rest of the hack involves modifying the gun for automatic firing. It’s a Nerf Stampede, which takes six D-cells to power the electrical firing system. [Chris] didn’t want to carry that weight around in the body of the weapon itself so he installed a port for external power and added a firing mechanism at the same time. It uses relays to complete the circuit normally operated by the trigger. Now logic-level signals have no problem dispensing justice from the brightly-colored device.

[via Make]

PCB Milling Tutorial

April 22, 2011 by Mike Szczys 26 Comments

[Juan Jose Chong] put together a set of videos and a PDF guide to milling printed circuit boards. You’ll find the pair of videos, totaling about twenty-two minutes, embedded after the break. In them, [Jaun] details the techniques used by the IEEE chapter at Texas Tech University to mill PCBs instead of using the traditional method of etching them. We’ve long been a fan of milled PCBs and often dream about the day we can retire the old iron we use for the toner transfer method.

In the tutorial, IsoPro is the software used to control the mill. The CAM files from a PCB design program are imported – they can come from many different programs including EagleCAD. A few setup steps let the operator configure the resolution necessary to mill the correct tolerance and from there the paths that outline each trace are calculated in software. In order to facilitate double-sided boards a reference hole is drilled in the copper clad board to accept a post on the mill table. Tape down the substrate with some foil tape, set the depth of the end mill bit, and let the machine do its thing. [Juan’s] video illustrates how quickly this can produce a rather complicated board, finishing in around 20 minutes.

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MindWave Is Developer (read: Hacker) Friendly Mind Control

April 22, 2011 by Mike Szczys 3 Comments

Here’s a setup to control a servo motor with your mind. [Danny Bertner] made this project happen by interfacing a MindWave headset with an Arduino. You might wonder what’s the big deal about that since we’ve covered quite a few mind control hacks that work this way? So far, the majority of those hacks used the Mindflex toy (to be fair there were several using the Force Trainer as well), which depends on a chip made by the company that is responsible for the MindWave. Both the Mindflex and the Force Trainer were reverse engineered to access the stream of data coming in from the EEG sensors. But NeuroSky is embracing the urge to mess with their products by offering developer tools.

[Danny] took advantage of these resources, using the comany’s own guide to interfacing with an Arduino (PDF). The quick clip after the break shows his finished project, grabbing data from the USB dongle that comes with the headset, converting it to the necessary levels for the Arduino, then processing the signals for display on and LED bar graph.

We can’t help but chuckle about the warranty-voiding disclaimer at the top of the PDF guide.

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Measuring The ~10 Kiloamp Output Of A Large Capacitor Bank

April 21, 2011 by Mike Szczys 22 Comments

[Norman] put together a rather impressive 22,500 uF capacitor bank. In addition to find things to torture with the strong magnetic field generated by a sudden discharge, he’d like to measure the current pushed from the device. He’s found a way to do this using a digital storage oscilloscope. To protect the oscilloscope [Norman] built his own interface box that includes a 50x voltage divider, and interfaces a current sensor called a Rogowski coil. When it comes time to run the experiment, he turns the safety lock-out key on the bank charger, then discharges the stored potential with the flip of a switch.

Take a look at the video after the break to see soda cans and hard drive platters mangled by the device. The oscilloscope measures the output near 10 kA, giving [Norman] the data he set out to capture. He’s entered this project into the Tektronix contest where it’ll compete with the piano tuner and laser light show tester just to name a few.

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