Turn A Ceiling Fan Into A Wind Turbine… Almost

It’s not uncommon to drive around the neighborhood on trash day and see one or two ceiling fans haphazardly strewn onto a pile of garbage bags, ready to be carted off to the town dump. It’s a shame to see something like this go to waste, and [Giesbert Nijhuis] decided he would see what he could do with one. After some painstaking work, he was able to turn a ceiling fan into a wind turbine (of sorts).

While it’s true that some generators and motors can be used interchangeably by reversing the flow of electricity (motors can be used as generators and vice-versa) this isn’t true of ceiling fans. These motors are a type called induction motors which, as a cost saving measure, have no permanent magnets and therefore can’t simply be used as a generator. If you make some modifications to them, though, like rewiring some of the windings and adding permanent magnets around them, you can get around this downside of induction motors.

[Giesbert] does note that this project isn’t a great way to build a generator. Even after making all of the changes needed to get it working, the motor just isn’t as efficient as one that was built with its own set of magnets. For all the work that went into it, it’s not that great of a time investment for a low-quality generator. However, it’s interesting to see the theory behind something like this work at all, even if the end result wasn’t a complete wind turbine. Perhaps if you have an old ceiling fan lying around, you can put it to better use.

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Trick Shot Bot Flings Balls Into Wine Glass Every Time

We’ve heard of beer pong, but we’re not sure we’ve heard of wine pong. And certainly never wine pong automated with a ping pong ball throwing robot like this one.

There’s not a huge amount of detail available in the video below, and no build log per se. But [Electron Dust] has a few shots in the video that explain what’s going on, as well as a brief description in a reddit thread about the device. The idea is to spin a ball up to a steady speed and release it the same way every time. The rig itself is made of wood and spun by plain brushed DC motors – [Electron Dust] explains that he chose them over PWM servos to simplify things and eliminate uncertainty in the release point. The ball is retained by a pair of arms, each controlled by a pair of hobby servos. An Arduino spins along with everything else and counts 50 revolutions before triggering the servos to retract and release the ball. A glass positioned at the landing spot captures the ball perfectly once everything is dialed in.

Here’s hoping that build details end up on his blog soon, as they did for this audio-feedback juggling machine. And while we certainly like this project, it might be cool if it could aim the ball into the glass. Or it could always reposition the target on the fly.

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Robotic Cheetah Teaches A Motors Class

It seems like modern roboticists have decided to have a competition to see which group can develop the most terrifying robot ever invented. As of this writing the leading candidate seems to be the robot that can fuel itself by “eating” organic matter. We can only hope that the engineers involved will decide not to flesh that one out completely. Anyway, if we can get past the horrifying and/or uncanny valley-type situations we find ourselves in when looking at these robots, it turns out they have a lot to teach us about the theories behind a lot of complicated electric motors.

This research paper (gigantic PDF warning) focuses on the construction methods behind MIT’s cheetah robot. It has twelve degrees of freedom and uses a number of exceptionally low-cost modular actuators as motors to control its four legs. Compared to other robots of this type, this helps them jump a major hurdle of cost while still retaining an impressive amount of mobility and control. They were able to integrate a brushless motor, a smart ESC system with feedback, and a planetary gearbox all into the motor itself. That alone is worth the price of admission!

The details on how they did it are well-documented in the 102-page academic document and the source code is available on GitHub if you need a motor like this for any other sort of project, but if you’re here just for the cheetah doing backflips you can also keep up with the build progress at the project’s blog page. We also featured this build earlier in its history as well.

Magnetic Bearings Might Keep This Motor Spinning For Millennia

We see our share of pitches for perpetual motion machines in the Hackaday tips line, and we generally ignore them and move along. And while this magnetic levitation motor does not break the laws of thermodynamics, it can be considered a perpetual motion machine, at least for certain values of perpetuity.

The motor that [lasersaber] presents in the video below is unconventional, to say the least. It’s not a motor that can do any useful work, spinning at a stately pace beneath its bell-jar enclosure as it does. The design is an extension of [lasersaber]’s “EZ-Spin” motor, which we’ve featured before, and has the same basic layout – a ring of coils wired in series forms the stator, while a disc bearing permanent magnets forms the rotor. The coils, scavenged from those dancing flowerpot solar ornaments, are briefly energized by the rotor passing over a reed switch, giving the rotor a little boost.

The difference here is that rather than low-friction sapphire bearings, this motor uses zero-friction magnetic levitation using pyrolyzed graphite discs. The diamagnetic material hovers above a rare-earth ring magnet, supporting a slender vertical shaft that holds the rotor and another magnetic bearing at the top. It’s fussy to adjust, but once it’s stable, the only friction in the system should be the drag caused by air in the bell jar. [lasersaber]’s current measurements of the motor running at slow speed are hard to believe – 150 nanoamps – leading to an equally jaw-dropping calculated run-time on a single AA battery of 89 millennia.

[lasersaber] is the first to admit that he’s not confident with his measurements, but it seems clear that his motor will likely outlive any chemical battery used to power it. Whatever the numbers are, we like the styling of the thing, and the magnetic bearings are cool too.

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This Vibrating Continuity Tester Is Quietly Useful

Continuity testing is one of the most valuable functions on the modern multimeter. It will help you investigate wiring problems in your car, tell you if you’re holding a nullmodem serial cable or the regular kind, and even reveal when you’ve accidentally shorted the data lines right to the power supply. However, all that beeping can get annoying, so [bitelxux] built a vibrating version instead.

The build was borne out of necessity; [bitelxux]’s meter lacked a buzzer, and it grew frustrating to always look at the display. In order to allow late night hacking sessions to go on undisturbed, an unobtrusive vibrating tester was desired, as opposed to the usual audible type. Two whiteboard markers donated their shells to the hack, fitted with small nails to act as probes. Inside, a pager vibration motor is connected, vibrating when continuity is found. The circuit runs from a 1.5V AA battery which neatly fits inside the marker shell.

It’s a basic build, but gets the job done with a minimum of fuss using parts that most makers probably have lying around. Of course, you can always go a slightly more complicated route and throw an Attiny at the problem.

Palm-Sized Gatling Gun Has 32 Mini Elastics With Your Name On Them

One thing 3D printers excel at is being able to easily create objects that would be daunting by other methods, something that also allows for rapid design iteration. That’s apparent inĀ [Canino]’s palm-sized, gatling-style, motorized 32-elastic launcher.

The cannon has a rotary barrel driven by a small motor, and a clever sear design uses the rotation of the barrels like a worm gear. The rotating barrel has a spiral formation of hooks which anchor the stretched elastic bands. A small ramp rides that spiral gap, lifting ends of stretched bands one at a time as the assembly turns. This movement (and therefore the firing control) is done with a small continuous rotation servo. While in theory any motor would do, using a servo has the advantage of being a standardized shape, and therefore easy to integrate into the design. A video is embedded below in which you can see it work, along with some close-ups of the action.

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Shred The Gnar Without Paddling For Waves

[Ben Gravy] isn’t your average pro surfer. For one thing, he lives in New Jersey instead of someplace like Hawaii or Australia, and for another he became famous not for riding the largest waves but rather for riding the weirdest ones. He’s a novelty wave hunter, but some days even the obscure surf spots aren’t breaking. For that, he decided to build a surfboard that doesn’t need waves. (Video, embedded below the break.)

The surfboard that [Ben] used for this project isn’t typical either. It’s made out of foam without any fiberglass, which makes the board less expensive than a traditional surfboard. The propulsion was handled by an electric trolling motor and was hooked up to a deep cycle battery mounted in the center of the board in a waterproof box. The first prototype ended up sinking though, as most surfboards can’t support the weight of a single person on their own without waves even without all the equipment that he bolted to it.

After some reworking, [Ben] was able to realize his dream of riding a surfboard without any waves. It’s not fast, but the amount of excitement that he had proves that it works and could fool most of us. This hack has everything, too: a first prototype that didn’t work exactly right and was fixed with duct tape, electricity used in a semi-dangerous way, and solving a problem we didn’t know we had. We hope he builds a second, faster one as well.

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