Scratch-built motor uses a clever design

[Lou] is on a hot streak when it comes to interesting builds. This time around he made his own motor using wood, PVC, some fasteners, and a bunch of enameled wire.

His method of building a commutator is intriguing. He first builds a rotor by cutting two opposing sides off of a PVC four-way connector and pushing a short galvanized pipe through what’s left. After adding two PVC nubs with caps and nails as pivot points he wraps the PVC and metal pipe with a continuous length of enameled wire. The enamel is then sanded off the windings around the PVC, and half is covered with electrical tape. The spinning rotor will cause the brushes to contact the bare wire during half of the rotation, and be insulated by the tape during the other half. The video after the break shows the motor in action, then walks you through each step of the build.

If you liked this video you should check out [Lou's] water bottle rocket launcher, or his automated Ping Pong table topper which stores the game in the ceiling.

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Building an electric-powered longboard for under $100

[Alan] doesn’t have to kick to get around town because he added a removable electric motor to his longboard. It looks great, and works just as well because he didn’t reinvent the wheel. The idea is a mashup of an electric Razor scooter and his long board.

The majority of the project revolved around mounting everything he needed to the board. When it comes to the drive wheel he designed a tension system. When a rider is not on the board the back wheels of the long board are off the ground by about an inch. The springs in the suspension system make it so when you do mount the board all wheels are touching, with the main drive wheel held tight to the pavement even while turning.

Unlike some electric skateboard builds [Alan] didn’t need to raise the board off the ground as the battery compartment is mounted on top of the deck. He added cooling fans for the hot summer days, and even used velcro to attach the charger so that he can juice it up when away from home. Check out his three minute show and tell embedded after the break.

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Robot servo control using smartphone audio jack

[Jim] has an old Android phone he’d like to use as a Robot brain. It’s got a lot of the things you’d want in a robot platform; WiFi, Bluetooth, a camera, an accelerometer, etc. But he needed some way to make the mobile, mobile. What he came up with is a chassis with servos that can be controlled by the phone’s audio port.

To start his adventure he crafted a square wave audio file in Audacity and then played it back on the Android music player. By monitoring the output on an oscilloscope he found the wave was well produced, with peaks of about 1V. With that in mind he designed a circuit using two transistors to amplify the signal, thereby creating a usable input for the servo motors. Each motor has one of these circuits connected to it, with the left and right channels from the audio jack driving them separately. In the clip after the break you can see he even wrote a simple Android app to extend the idea to a more usable level.

This is a similar technique as used by the recon robot we saw about a year ago.

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‘Vortex-drive’ for underwater ROV propulsion

This is [Lee von Kraus'] new experimental propulsion system for an underwater ROV. He developed the concept when considering how one might adapt the Bristlebot, which uses vibration to shimmy across a solid surface, for use under water.

As with its dry-land relative, this technique uses a tiny pager motor. The device is designed to vibrate when the motor spins, thanks to an off-center weight attached to the spindle. [Lee's] first experiment was to shove the motor in a centrifuge tube and give it an underwater whirl. He could see waves emanating from the motor and travelling outward, but the thing didn’t go anywhere. What he needed were some toothbrush bristles. He started thinking about how those bristles actually work. They allow the device to move in one direction more easily than in another. The aquatic equivalent of this is an angled platform that has more drag in one direction. He grabbed a bendy straw, using the flexible portion to provide the needed surface.

Check out the demo video after the break. He hasn’t got it connected to a vessel, but there is definitely movement.

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Chibikart: step-by-step lets you build your own tiny-wheel racer

[cHaRlEsg] posted a rant, then posted full instruction on how to build this electric go-kart for yourself.

Now the rant calls this an unobtainium-free sibling to the Chibikart. We’re sad to report that the unobtainium he’s talking about are the hyper-awesome hand-wound hub motors that powered the original kart which left us dumbstruck after seeing it for the first time. But look, few mortals have the skills and tools necessary to manufacture those circular marvels of modern engineering.

So you’ll just need to settle for stuff you can buy to assemble the tiny kart seen here. It’s all-electric, using two DC motors to power the rear wheels. You can catch it racing around the hallways in the video after the break. The only thing we can see missing from the equation (other than red shells and the like) is a helmet and bumpers (you’ll see why at the end of the clip).

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Motorized skateboard just begging to be your next project

You’re not going to be doing any flip-tricks with this board, but it’ll let you get around without getting sweaty. The ZBoard is a motorized skateboard which is in the pre-order stages thanks to a successful Kickstarter campaign. It’ll set you back $500 now or $600 later. With that kind of budget wouldn’t it be fun to build your own?

This base model can go about five miles or five hours between charges. It carries a seal lead-acid battery (really?) but if you upgrade to the pro model for just $250 more you get a LiFePo that doubles the range (but curiously not the run time). To make it go there are pressure sensitive foot pads on the front and rear of the deck. This allows you to go slow with just a bit of pressure, or put the pedal to the metal to get up to the 15 mph speed limit. It’s even got regenerative breaking to slow things down while giving a boost to the battery.

The idea is nothing new. But the cleanliness that this product brings to market is something to be respected. We’re hoping this sparks some inspiration for a rash of DIY clones, kind of like we’ve seen with the Segway.

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Heliowatcher positions solar panels for highest efficiency

[Jason Wright] and [Jeremy Blum] are showing off the project they developed for their Designing with Microcontrollers course at Cornell University. They call it the Heliowatcher, and if you know your Greek mythology we’d be you figured out this watches the movement of the sun and adjust a solar panel to follow it.

Their design is simple and effective. The base is mounted like a Lazy Susan, able to pivot on the horizontal plane. The bottom edge of the solar panel is mounted with two door hinges, with a motorized screw jack used to raise and lower it. The system uses a GPS to provide geographical position, day, and time feedback. This is used in conjunction with an array of four LEDs to determine the best position of the panel. Those LEDs are acting as light sensors; when the top and the bottom detect similar levels, the panel is at its most efficient orientation. The left and right LED sensors work the same way.

Now if we can just work out a self-cleaning system to keep the panels free of the dirty film that builds up over time we’d be set!

[Read more...]

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