Step the Halbach from My Magnets

[Klaus Halbach] gets his name attached to these clever arrangements of permanent magnets but the effect was discovered by [John C. Mallinson]. Mallinson array sounds good too, but what’s in a name? A Halbach array consists of permanent magnets with their poles rotated relative to each other. Depending on how they’re rotated, you can create some useful patterns in the overall magnetic field.

Over at the K&J Magnetics blog, they dig into the effects and power of these arrays in the linear form and the circular form. The Halbach effect may not be a common topic over dinner, but the arrays are appearing in some of the best tech including maglev trains, hoverboards (that don’t ride on rubber wheels), and the particle accelerators they were designed for.

Once aligned, these arrays sculpt a magnetic field. The field can be one-sided, neutralized at one point, and metal filings are used to demonstrate the shape of these fields in a quick video. In the video after the break, a powerful magnetic field is built but when a rare earth magnet is placed in the center, rather than blasting into one of the nearby magnets, it wobbles lazily.

Be careful when working with powerful magnets, they can pinch and crush, but go ahead and build your own levitating flyer or if you came for hoverboards, check out this hoverboard built with gardening tools.


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Here’s Why Hoverboard Motors Might Belong In Robots

[madcowswe] starts by pointing out that the entire premise of ODrive (an open-source brushless motor driver board) is to make use of inexpensive brushless motors in industrial-type applications. This usually means using hobby electric aircraft motors, but robotic applications sometimes need more torque than those motors can provide. Adding a gearbox is one option, but there is another: so-called “hoverboard” motors are common and offer a frankly outstanding torque-to-price ratio.

A teardown showed that the necessary mechanical and electrical interfacing look to be worth a try, so prototyping has begun. These motors are really designed for spinning a tire on the ground instead of driving other loads, but [madcowswe] believes that by adding an encoder and the right fixtures, these motors could form the basis of an excellent robot arm. The ODrive project was a contender for the 2016 Hackaday Prize and we can’t wait to see where this ends up.

Boxes, Form An Orderly Queue Behind The Armchair!

If you have ever been to a hacker camp, you’ll know the problem of transporting all your stuff to your hackerspace village, or to wherever you’ll be basing yourself for the duration. The car park is always too far away, whatever trolley you’ve brought along is never big enough, and the terrain you have to drag everything over feels more like the Chilkoot Trail than a city sidewalk.

[Jan Henrik] and [Niklas Fauth] have an effective solution to all your hacker camp transport woes, in the form of a motorized platform designed to carry a storage box. Underneath the platform are a pair of hoverboard motors and their controller board reflashed with a custom firmware.

You might be now looking at it and thinking “So what?”, for a single platform is handy but hardly a comprehensive transport solution. What makes this one impressive though is that it’s not a single board, instead there is a swarm of them for which they appear to have implemented some form of optical following system which is teased through the video we’ve placed below the break and with this Tweet, but not in detail yet in the wiki page. A neat train of platforms follows the lead one, transporting everything with minimum fuss. What can we say, except “We want one too!”. There is some code to be found in a GitHub repository, should you be interested in having a go for yourself.

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Hoverboard Reborn For Electric Rollerblading

Rollerblading is fun, but who needs all that pesky exercise? Wouldn’t strapping on the blades be so much more tempting if you had an electric pusher motor to propel you along your way?

We have to admit that we raised a wary eyebrow as we first watched [MakerMan]’s video below. We thought it was going to be just another hoverboard hack at first, but as we watched, there were some pretty impressive fabrication skills on display. Yes, the project does start with tearing into a defunct hoverboard for parts, primarily one wheel motor and the battery pack. But after that, [MakerMan] took off on a metalworking tear. Parts of the hoverboard chassis were attached to a frame built from solid bar stock — we’ll admit never having seen curves fabricated in quite that way before. The dead 18650 in the battery pack was identified and replaced, and a controller from an e-bike was wired up. Fitted with a thumb throttle and with a bit of padding on the crossbar, it’s almost a ride-upon but not quite. It seems to move along at quite a clip, even making allowances for the time-compression on the video.

We’ve seen lots of transportation hacks before, from collapsible longboards to steam-powered bicycles, but this one is pretty unique.

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Open Source Firmware For Hoverboards

2015 was two years ago, and to the surprise of many, we actually had hoverboards at the time. Of course, these weren’t Back to the Future-style hovering skateboards; they were crappy two-wheeled balancing scooters that suffered a few battery explosions and were eventually banned from domestic flights by some carriers. But oh boy, there were some funny Vines of these things.

While the rest of the world moved on from hoverboards, [Casainho] has been working on Open Sourcing the firmware for these interesting bits of electronics and motors. Now, his work is wrapping up and he has new firmware for electric unicycles and hoverboards.

The popular and cheap electric unicycles and hoverboards that have been swimming across the Pacific from the great land of Ali Baba for the past five years are based around a single, cheap controller board. This controller board is built around the STM32F1038T6 microcontroller, and are able to control a pair of three-phase brushless motors. The teardown began on the electric unicycle forum and was completely documented in a GitHub repo.

The Open Source firmware is now mostly complete, although the necessary self-balancing function doesn’t work. We’re thinking that’s alright; with this new firmware, these electric unicycles have a crazy amount of torque and could be the basis for a few very cool builds. You can check out a video of this torque below.

If two wheels seems far too safe, exercise your inner daredevil with a 3D printed unicycle conversion for a hoverboard.

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Scratch-Built EV From Hoverboards

Electric vehicles are everywhere now. Even though battery technology hasn’t had the breakthrough that we need to get everyone out driving an electric car, the price for batteries has dropped enough that almost anything else is possible. The hoverboard was proof of this: an inexpensive electric vehicle of sorts that anyone who was anyone in 2015 had. Taking his cue from there, [Harris] used off-the-shelf parts normally used for hoverboards to build his own battery-powered trike.

The trike is homemade from the ground up, too. The H-frame was bolted together using steel and lots and lots of bolts. Propulsion comes from a set of hub motors that are integrated into the wheels like a hoverboard or electric bicycle would have. Commonly available plug-and-play lithium batteries make up the power unit and are notably small. In fact, the entire build looks like little more than a frame and a seat, thanks to the inconspicuous batteries and hub motors.

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