DIY Sound Localization Sensor

May 10, 2011 by Mike Nathan 32 Comments

sound_localization_sensor

Sound localization is very popular in law enforcement circles due to its accuracy and ability to quickly separate gunshots from other similar noises. These systems don’t come cheap, and after trying to build one himself, [Fileark] knows why.

He thought it would be neat to build a sound localization sensor based on how the human ear determines a sound’s source. Once he got started however, he realized just how hard it was to do localization just right.

He used an LM324N op-amp as a volume comparator, which he says works decently enough though he figures there are ICs out there that can do a better job. [Fileark] reports that the sound detector works well when the source is within about a foot of the sensors, but performance deteriorates at greater distances. He may consider using an ARM Cortex-M3 as his sound processor if he builds a second version, since the Arudino he used just doesn’t have enough power to sample and run calculations within the 10-50 microsecond window he requires.

Keep reading to see a video of his sound localization sensor in action.

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Open Source Linear Bearing System

May 10, 2011 by Mike Nathan 53 Comments

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While we normally don’t make it a habit to feature Kickstarter projects, we couldn’t pass this one up. [Barton Dring] from BuildLog.net is putting together a project called MakerSlide that we’re sure will interest many of you out there.

Through his various CNC builds, he has found that one of the more expensive and frustrating components to obtain is a linear bearing system. He notes that commercial systems are expensive, and while an occasional eBay bargain can be found, it’s not the ideal way of going about things. He also points out that homebrew systems usually work after some tuning and adjustments, but can be time consuming to build.

He is proposing a v-groove bearing system, complete with wheels made from Delrin, as a standardized replacement for all of the aforementioned solutions. He anticipates selling the rails for about 10 cents per centimeter, putting the average cost of a 4 foot system around $20.

As a bonus, he is offering up free MakerSlide materials to anyone that sends him a “new, innovative or interesting open source design or basic idea that uses the material.” You would only have to pay shipping in order to get your new project off the ground.

Standardization is always good, and seeing this rail system go into production would definitely benefit the hacker community. Take a minute to check it out if you are so inclined.

DIY Portal Turret Is… Looking Pretty Good.

May 10, 2011 by Jesse Congdon 19 Comments

[Ryan Palser] wrote in to tell us about his Portal Turret. [Ryan] set about making this Portal 1 style turret by first carving a Styrofoam form, bondo and waxing then casting molds of the various components. Anyone interested in mold making (like us) should check out all the pictures and comments in the stream. The turret’s camera lens style eye has some excellent detail including a laser cut aperture with text inlay. A couple LEDs behind the eye assembly provide the signature red glow and evidently [Ryan] also fitted the little guy with a red laser. An internal Arduino (Incident Resolution Chip?) takes ques from a PIR sensor mounted in one of the turret’s arms to play one of 17 sound clips through a sparkfun MP3 player shield. In order to fight repetition the sound module runs through a playlist of the 17 tracks then shuffles it before playing through again. Theme music can also be spammed by pressing a button in the back of the motion sensing arm. The turret can be battery powered or plugged into a wall socket for constant operation. All that’s missing are the Aperture-Brand Resolution Pellets. We would love to see this integrated with some similar turret projects previously featured here.

Are you still there? We have more Aperture Science stuff including a Sentry Turret, Weighted Companion Cube, and even a portal shirt. If you are interested in more model making check out the spectacular Daft Punk helmet build from a little while back.

Human-powered Quadcopter Flies Live Tomorrow

May 10, 2011 by Mike Szczys 30 Comments

A team from the University of Maryland will be taking their human-powered helicopter to the air tomorrow. The current flight record for this type of vehicle is just over 19 seconds of flight at a height of about 8 feet. What surprises us about this attempt is that they’re not pedaling just one main rotor. It seems that the most success in man-powered helicopter flight has come from helicopters with a total of four rotors.

The image seen above is a 2009 test of just one of the four rotor arms that will go into UMD’s finished chopper. Fully assembled it will be about 1/3 the size of a football field, dwarfing the autonomous quadcopters we usually see around here. Get the details about the design from the video after the break. It’s interesting to hear [Dr. Antonio Filipone] talk about the need to generate both the lift and the thrust, where human-powered fixed-wing aircraft only need the thrust. He predicts that human-powered helicopter flight is possible, but that it will only lift the aircraft, with little possibility of moving it in one direction or the other.

The team is attempting to grab the $250,000 Sikorsky Prize with their creation. We wish them the best of luck.

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Bit Banging VGA From An SD Card Slot

May 10, 2011 by Mike Szczys 14 Comments

If you’ve got some favorite electronic device that includes an SD card slot but doesn’t have a video out port you may be able to push VGA signals through the card reader conductors. That’s exactly what’s going on above with the Ben NanoNote, a sub-$100 Linux device which we’ve seen using its SD card slot as general I/O before.

The hardware to capture the signals includes a breakout board for the card slot. Free-formed on the other end of that connector card is a gaggle of resistor which handle level conversion for the VGA color signals, with a VGA cable taking it from there to the monitor. The software that makes this happen is a dirty hack, blocking all other functions while it displays a still image. But we’re sure that it can be cleaned up somewhat. Just don’t hold out hopes for full-motion video, this little guy just doesn’t have it in him.

[via Dangerous Prototypes via Slashdot]

Roll Your Own Capacitors – High Voltage Edition

May 10, 2011 by Mike Szczys 13 Comments

[Grenadier] tipped us off about his method for building your own high-voltage capacitors. He thought the paper and foil capacitor project was a nice introduction to the concepts, but at the same time he knew he could produce a much more powerful device.

For the dielectric he is using acetate film. This is the material from which overhead transparency sheets are made. He stuck with aluminum foil for the two plates. Just roll the foil flat with a rolling-pin, use thin wire to minimize the air that will be trapped between the dielectric layers, and make sure the foil plates are at least 4cm shorter than the acetate film on each end to prevent leakage. After rolling and securing the capacitor with zip ties you’ll be ready for the 3nF worth of fun seen in the video after the break. [Grenadier] mentions that this can be improved further if you were to vacuum impregnate the device with beeswax.

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Don’t Hit That Switch!

May 10, 2011 by Mike Nathan 44 Comments

switch_box

Hackaday reader [Danukeru] sent us a video featuring a box-based robot with an interesting personality. The box is fairly simple and from the outside seems to consist only of a switch and an LED. When the switch is flipped however, the box comes to life.

When the box is activated, the lid opens, and a small arm reaches out to turn the switch off. We’ve seen that plenty of times, but this one turns out to be a little different. In the video, this process seems to repeat a couple dozen times before the robot gets angry and flips out. At first we thought that the end portion of the video was done with a bit of digital trickery, but after reviewing the creator’s blog, it looks like it could be legit. It is very hard to see the box’s innards in the video, but it does house a remote control car chassis that allows it to move around and spin out, as seen below.

It’s a pretty neat project, and if you can handle reading the creator’s site via Google translate, there is plenty of picture documentation of the build process for your perusal.

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