RC Pontoon From A Toy Car

[Kevin Sandom] built this boat using a radio controlled toy car. The two pontoons are recycled from Styrofoam packaging material using some thick wire to connect them and provide a framework for the propulsion and control circuitry. The motor itself is a hobby outboard, which really only required [Kevin] to develop a method for steering. He walks us through the build process in the video after the break, where we find out that the original toy has a pretty bad design flaw. It seems the car used four AA batteries to drive the motor, but one of the four batteries was also used separately from the other three to power the control circuitry. Running that battery down faster than the others shortens the life of the whole.

This is considerably easier than the underwater ROV hacks we’ve seen before. We do think that it would make for a fun weekend project, and we’d bet you’ll get some weird looks for piloting what appears to be garbage around a pond.

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Lightsaber Boasts Detachable Blade And Crystal Chamber

[Bradley W. Lewis] continues to amaze us with this Return of the Jedi Lightsaber build. You’ll remember his fine work from his previous Episode IV replica. He’s taken the parts that turned out well for him and expanded upon them. In the demonstration after the break you’ll see the new version has a removable blade (which happens to house 90 LEDs). Just like the last time he’s got a Hasbro sound board and a speaker to add the Jedi-like sound effects. But there’s another trick up his sleeve. Two parts of the grip slide apart on a spring-loaded assembly to reveal the crystal that gives the weapon its sting. And as we found out the last time, [Bradley] really knows how to share his work in the build log.

Oh, and the drawings above? Well, someone who plans this meticulously obviously knows what they’re doing.

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Kinetic Sculpture Takes A Page From Modern Life

The blurry image above is a snap of toy cars as they zoom around a multi-lane, multi-level, maniacal-maze called Metropolis II. We originally took a look at the video after the break (do it now!) but found more information on [Chris Burden’s] kenetic sculpture in this NYT article. He and eight studio artists began work on the project back in 2006. They built 1200 custom designed cars and gave them a huge city to traverse, with up to 18 lanes at times. The work is not yet done, and the video below is dated (having been filmed in 2009), but project is slated to conclude in about two months and the installation has already been snapped up by the Los Angeles County Museum of Art.

And here we thought this was the product of an out-of-work packaging system design engineer. Nope, it’s art, and it certainly eclipses other kinetic sculptures we’ve seen.

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RC Plane Built Using Pieces Of An RC Car

This hack’s old as dirt to be sure, but new to us and a great accomplishment. The plane above, which is meant to fly without an operator, has been given RC control thanks to parts from that little car. The transmitter and receiver pair are the obvious transplant, but how do you add steering to a $7 plane that wasn’t manufactured to have that feature? The tail was cut and reconnected with mylar hinges to turn it into a rudder. A rare earth magnet and a coil are also thrown into the mix to provide movement. Basically this is a simple solenoid where the coil pushes against the magnet when energized, actuating the rudder. This in combination with an upgraded motor allows for both speed control and yaw. It doesn’t look like you can control roll and pitch but what more can you really expect?

This would be a nice first step on that path to building an epic flying camera rig.

[Thanks Rob]

Lego Machine Predicts Future Eclipses

Hidden behind the white face plates of this machine are racks of gears that make up a replica of one of the oldest known mechanical computers. This is a working model of the Antikythera mechanism made from Lego pieces. In the video, which you absolutely can’t miss after the break, The machine is disassembled into its various components. Each mechanical unit takes advantage of gear ratio combinations to perform numerous levels of mathematical functions in order to display the date and time that future celestial events will occur.

The background information on the original device reads like the script for a sequel to The Goonies. Believed to date back to 100-150 BC, the stone bronze mechanism was recovered from a shipwreck around the turn of the twentieth century. The use of x-ray analysis helped to unlock the functions and confirm the theories of its operation.

Part of what makes this so interesting is the historical connection. But the production quality of the video (which to be fair, seems to be an advertisement) really brings home how complicated this process is. Now it’s time for us to watch the video a few more times, sketching out the gearing to see that this works as they say it does.

Want more of the Antikythera mechanism? Check out the model built by [Tatyana van Vark].

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Nerf Gun Converted To CO2 Powered Semi-automatic

[Philysteak527] modified a Nerf rifle, making it semi-automatic thanks to the powers of compressed air. This is not a simple change to make, and rests on his ability to design and manufacture a bolt-action that fits in the gun, works with the Nerf ammo, and uses a CO2 canister and solenoid valve for the firing action. Knowing that, it’s not surprising to find that he’s an engineering student at Stony Brook University. He started with some POM, or polyoxymethylene plastic sold under the brand name Delrin, and used a CNC lathe to machine the parts for the bolt. Add in some brass fittings, a solenoid, tubing, and the electronics and you’re in business.

We’ve embedded the test footage after the break. Looks like the new internals allow a rather fast firing rate (maybe 2-3 shots per second?) and achieve a distance between seventy and one hundred feet.

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Radar Gun Teardown

[Jeri Ellsworth] is at it again, this time she takes apart a hot wheels speed gun and in the process she does a good job of  explaining how radar can be used to measure speed.  She also demonstrates a way to determine if an object is approaching or receding from the radar gun.

The Doppler shift is one way to remotely measure the speed of an object. It works by measuring the change in frequency of a wave after it strikes an object. Rather than measuring the Doppler shift of the returning wave most radar guns use the phase shift. The reason is that the frequency shift of a relativly slow object (60mph), to a relitivly high frequency signal(10GHz) is small (about 0.893Hz), where the phase shift varies based on the distance of the object.  This is all just a stepping stone in her quest to build a crude TSA body scanner.