Year: 2011

Hackaday Links: December 7, 2011

December 7, 2011 by 12 Comments

LED Neurons

[Alexandra Olivier] put up an art installation at Wellesley College that looks like a bunch of neurons built out of LEDs. The neurons are connected to a couple PIR sensors and ‘fire’ whenever movement is detected. The result is a lot like being inside a brain. Fitting, then, that the installation is called Social Synapses.

Last year’s big toy was always evil, though

Last year, [Andrew] had to fight the throngs of shoppers to get the must have toy of the season, a Zhu Zhu pet. Since these robotic hamster things have spent the last 11 months in the back of a closet, it seems reasonable to make them evil. They’re still not as evil as a demonic Furby….

So we call it a bifocal, right?

There’s an old photography trick for a really hacky macro setup – just turn the lens around. Well, what if you wanted automatic metering and flash control? Simple, just electrically reverse the lens. Bonus points for being able to use the lens regularly as well.

Control all the bands

Well here’s something cool: an all-in-one USB 315mhz, 433mhz, and 868mhz transceiver. What can you do with it? Well, [codeninja] can control the outdoor lights for two of his neighbors, open gates and doors, crash his weather station, and just about anything else in those bands. It’s pretty much like war driving for important stuff nobody cares about.

So this is our favorite holiday now

There’s a Dutch tradition to play Sinterklaas and make someone a present. [Jenor] decided to build an antique-looking DC voltmeter with a pair of vacuum tubes. The tubes don’t work anymore, but the heaters still provide a nice warm glow. It’s a bit large to be regularly used as a piece of test equipment, but it really does look awesome. Very steampunkey, and it’s the though that counts anyway.

Aluminum Bending Tutorial And A DIY Brake

December 7, 2011 by 10 Comments

What makes a project really exceptional? Part of it is a, ‘gee, that’s clever’ angle with a little bit of, ‘that’s actually possible.’ One thing the Hack a Day crew really appreciates is awesome enclosures. Altoids tins will get you far, but to step up to the big leagues you’ve got to bend some aluminum. Luckily, [Rupert] sent in a great tutorial on bending aluminum sheets for enclosures.

To make his press brake, [Rupert] scavenged a few pieces of 38mm bamboo worktop scraps. After assembling a few of these pieces with some hinges, he was ready to bend some aluminum.

One trick [Rupert] picked up is scoring the sheet metal on the inside of a future bend. For [Rupert]’s project, he sent his 3mm aluminum sheet through a table saw set to cut 1mm deep. Of course this should only be done with a blade designed for non-ferrous metals with as many carbide teeth as possible. Judging from [Rupert]’s homebuilt Hi-Fi that used this construction technique, the results are phenomenal.

Awesome Little UAV Flies 1 Km

December 7, 2011 by 14 Comments

After going to an SMD soldering workshop at the Stuttgart hackerspace ShackSpace, [Corvus] decided to be an over achiever and build a flight controller for his very own unmanned aerial vehicle.

The airplane itself is a regular store-bought foam contraption, and not terribly interesting in and of itself. Autonomous flight piques some interest, though. A custom flight controller PCB was designed and built by [Corvus] to work alongside a tiny STM32 Linux board. These two boards, combined with the OpenPilot project allow the plane to keep altitude, bearing, speed, and position in check autonomously. Telemetry between the ground station and vehicle is handled by UAVTalk and a ThinkPad.

In the video after the break, [Corvus] piloted the plane up to altitude, then directed it to fly 500 meters North and turn around. The result was an autonomous flight of over one kilometer. The next stage of the project is implementing some SLAM applications with optical path finding and obstacle avoidance.

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Web-enabled Kinect

December 6, 2011 by 11 Comments

There are Kinect hacks out there for robot vision, 3D scanners, and even pseudo-LIDAR setups. Until now, one limiting factor to these builds is the requirement for a full-blown computer on the device to deal with the depth maps and do all the necessary processing and computation. This doesn’t seem like much of a problem since [wizgrav] published Intrael, an HTTP interface for the Kinect.

[Eleftherios] caught up to [wizgrav] at his local hackerspace where he did a short tutorial on Intrael. [wizgrav]’s project provides each frame from the Kinect over HTTP wrapped up in JSON arrays. Everything a Kinect outputs aside from sound is now easily available over the Internet.

The project is meant to put computer vision outside the realm of desktops and robotic laptops and into the web. [wizgrav] has a few ideas on what his project can be used for, such as smart security cameras and all kinds of interactive surfaces.

After the break, check out the Intrael primer [wizgrav] demonstrated (it’s Greek to us, but there are subtitles), and a few demos of what Intrael ‘sees.’

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Exterior-grade Electrical Box As Project Enclosure

December 6, 2011 by 14 Comments

The quest for a project box is always a balance between cost, complexity, and style. We think [Pcmofo] really finds the mark with his exterior electrical box enclosures. He took the time to document his fabrication process for those that want to replicate his look.

These grey plastic boxes are meant to keep the elements away from home and commercial electrical systems. They’re easy to find and come in many different sizes (this one is 8″ square and 4″ deep). The plastic is very rigid, but still easy enough to work with simple tools.

[Pcmofo] starts by eyeballing the placement of his components. Once he has a good idea of where each should be located he grabs a caliper and uses Adobe Illustrator or Inkscape to design a template. This is attached with painter’s tape, and rough openings are made using a drill press. The holes are brought to the final size by hand using files for a nice finished edge. When it comes time to mount hardware, the plastic is strong enough to hold threads if you are careful when using the tap to cut them.

The example enclosure houses a temperature controller for fermenting beer. You can see some video of the enclosure embedded after the break.

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Echo Box Shakes Itself To Make Sound

December 6, 2011 by 6 Comments

The echo box performs exactly as its name implies. If you tap out a rhythm on the lid, it will tap the same thing back to you. Except it isn’t tapping to make the sound, but vibrating.

The concept is similar to the Knock Block. In that hack, a piezo element detected a rapping on the wooden enclosure and repeated the rhythm by striking the lid with a solenoid. This iteration also uses a piezo element as the sensor. In the image above you can see a segment of PVC pipe in the upper corner. That houses the element, sandwiched between two pieces of wine bottle cork. That cork just touches the lid of the box, transferring the vibrations to the element.

The sound is created by a motor with an offset weight on its spindle. When the motor spins, it causes vibrations. The enclosure is one wood box inside of another, so the vibrating motor cause the inner box to shake against the outer one to make noise. Hear it for yourself in the clip after the break.

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Reverse Voltage Protection With A P-FET

December 6, 2011 by 51 Comments

[Afroman’s] latest video shows you how to add reverse voltage protection with minimal power loss. At some point, one of your electronic concoctions will turn out to be very useful. You want to make sure that a battery plugged in the wrong way, or a polarity mistake with your bench PSU doesn’t damage that hardware. It’s easy enough to plop in a diode for protection, but as [Afroman] points out, that wastes power in the form of heat when the circuit is working correctly. His solution is to add a P channel MOSFET which only allows power to flow when the polarity of the source voltage is correct.

The schematic above shows the P-FET on the high side of the circuit. The gate is hooked to ground, allowing current to move across the DS junction when the battery is connected. This design also uses a clamping diode to keep the gate voltage within a safe range. But there are P-FETs out there that wouldn’t need that diode or resistor. This method wastes ten times less power than a simple diode would have.

We’ve embedded the video after the break where [Afroman] shares the math and reasoning behind his component choices.

Continue reading “Reverse Voltage Protection With A P-FET” →