Emergency Torch Runs Without Batteries

It’s always good to have a torch on hand for emergencies. Unfortunately, sometimes these torches can be forgotten, and wind up with dead batteries when you need them most. For those cases, this build from [techrallyofficial] is just the ticket.

Instead of a battery, the torch relies on a 1.5 farad supercapacitor to store energy. The body of the torch is constructed out of PVC pipe and fittings, and packs strong neodymium magnets inside. A coil of wire wrapped is formed around an old solder spool, which, when shaken past the magnets, generates a current. This is rectified with a series of diodes and charges the supercapacitor, powering the light.

It’s a classic design that is available commercially, but it’s one easily replicated in the home shop, too. It would make a great educational project, particularly as students would be left with a useful device to take home at the end of the lesson. We’ve seen others resurrect commercial builds with upgrades, too. Video after the break.

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Hackaday Links: January 5, 2020

It looks like the third decade of the 21st century is off to a bit of a weird start, at least in the middle of the United States. There, for the past several weeks, mysterious squads of multicopters have taken to the night sky for reasons unknown. Witnesses on the ground report seeing both solo aircraft and packs of them, mostly just hovering in the night sky. In mid-December when the nightly airshow started, the drones seemed to be moving in a grid-search pattern, but that seems to have changed since then. These are not racing drones, nor are they DJI Mavics; witnesses report them to be 6′ (2 meters) in diameter and capable of staying aloft for 90 minutes. These are serious professional machines, not kiddies on a lark. So far, none of the usual government entities have taken responsibility for the flights, so speculation is all anyone has as to their nature. We’d like to imagine someone from our community will get out there with radio direction finding gear to locate the operators and get some answers.

We all know that water and electricity don’t mix terribly well, but thanks to the seminal work of White, Pinkman et al (2009), we also know that magnets and hard drives are a bad combination. But that didn’t stop Luigo Rizzo from using a magnet to recover data from a hard drive. He reports that the SATA drive had been in continuous use for more than 11 years when it failed to recover after a power outage. The spindle would turn but the heads wouldn’t move, despite several rounds of percussive maintenance. Reasoning that the moving coil head mechanism might need a magnetic jump-start, he probed the hard drive case with a magnetic parts holder until the head started moving again. He was then able to recover the data and retire the drive. Seems like a great tip to file away for a bad day.

It seems like we’re getting closer to a Star Trek future every day. No, we probably won’t get warp drives or transporters anytime soon, and if we’re lucky velour tunics and Spandex unitards won’t be making a fashion statement either. But we may get something like Dr. McCoy’s medical scanner thanks to work out of MIT using lasers to conduct a non-contact medical ultrasound study. Ultrasound exams usually require a transducer to send sound waves into the body and pick up the echoes from different structures, with the sound coupled to the body through an impedance-matching gel. The non-contact method uses pulsed IR lasers to penetrate the skin and interact with blood vessels. The pulses rapidly heat and expand the blood vessels, effectively turning them into ultrasonic transducers. The sound waves bounce off of other structures and head back to the surface, where they cause vibrations that can be detected by a second laser that’s essentially a sophisticated motion sensor. There’s still plenty of work to do to refine the technique, but it’s an exciting development in medical imaging.

And finally, it may actually be that the future is less Star Trek more WALL-E in the unlikely event that Segway’s new S-Pod personal vehicle becomes popular. The two-wheel self-balancing personal mobility device is somewhat like a sitting Segway, except that instead of leaning to steer it, the operator uses a joystick. Said to be inspired by the decidedly not Tyrannosaurus rex-proof “Gyrosphere” from Jurassic World, the vehicle tops out at 24 miles per hour (39 km/h). We’re not sure what potential market for these things would need performance like that – it seems a bit fast for the getting around the supermarket and a bit slow for keeping up with city traffic. So it’s a little puzzling, although it’s clearly easier to fully automate than a stand-up Segway.

Tracking Wasted Time With A Ferrofluid Clock

We know this project is supposed to be about developing a fine-looking ferrofluid clock, and not about the value of procrastination. But after watching the video below, see if you don’t think that procrastination has taken these two students further than expected.

We first ran into [Simen] and [Amund] several months ago when they launched their ferrofluid project in a fit of “There’s got to be more to life than studying.” It seemed then that building a good-looking, functional ferrofluid display would be a temporary distraction, but the problems posed proved to be far deeper and thornier than either of the electrical engineering students expected. The idea is simple: contain a magnetic fluid between two transparent panels and create pixels using an array of electromagnets to move dots of the fluid around. The implementation, however, was another matter, with the ferrofluid itself proved to be the biggest obstacle. All the formulas they tried seemed to coagulate or degrade over time and tended to stain the glass. While the degradation was never fully sorted, they managed to work around the staining by careful cleaning of the glass and using a saturated brine solution to fill the container.

Backed by 252 electromagnets and drivers on ten custom PCBs, the video below shows the (mostly) finished panel in action as a clock. We’re impressed by the smoothness of the movements of each pixel, even if there’s a bit of drooping at the bottom thanks to gravity. As for the future of the project, that’s unclear since [Simen] is headed off for a NASA internship. We’re not sure if that was despite or because of this procrastination-driven project, but we congratulate him either way and look forward to hearing more from both of them in the future.

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Spin Me Right Round, Baby: Generator Building Experiments For Mere Mortals

How many of you plan to build a wind-powered generator in the next year? Okay, both of you can put your hands down. Even if you don’t want to wind your coils manually, learning about the principles in an electric generator might spark your interest. There is a lot of math to engineering a commercial model, but if we approach a simple version by looking at the components one at a time, it’s much easier to understand.

For this adventure, [K&J Magnetics] start by dissect a commercial generator. They picked a simple version that might serve a campsite well, so there is no transmission or blade angle apparatus to complicate things. It’s the parts you’d expect, a rotor and a stator, one with permanent magnets and the other with coils of wire.

The fun of this project is copying the components found in the commercial hardware and varying the windings and coil count to see how it affects performance. If you have ever wound magnet wire around a nail to make an electromagnet, you know it is tedious work so check out their 3D printed coil holder with an embedded magnet to trigger a winding count and a socket to fit on a sewing machine bobbin winder. If you are going to make a bunch of coils, this is going to save headaches and wrist tendons.

They use an iterative process to demonstrate the effect of multiple coils on a generator. The first test run uses just three coils but doesn’t generate much power at all, even when spun by an electric drill. Six windings do better, but a dozen finally does the trick, even when turning the generator by hand. We don’t know about their use of cheap silicone diodes though, that seems like unintentional hobbling, but we digress.

Making turbine blades doesn’t have to be a sore chore either, and PVC may be the ticket there, you may also consider the vertical axis wind turbine which is safer at patio level. Now, you folks building generators, remember to tip us off!

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Jigsaw Motor Uses PCB Coils For Radial Flux

Electric motors are easy to make; remember those experiments with wire-wrapped nails? But what’s easy to make is often hard to engineer, and making a motor that’s small, light, and powerful can be difficult. [Carl Bugeja] however is not one to back down from a challenge, and his tiny “jigsaw” PCB motor is the latest result of his motor-building experiments.

We’re used to seeing brushless PCB motors from [Carl], but mainly of the axial-flux variety, wherein the stator coils are arranged so their magnetic lines of force are parallel to the motor’s shaft – his tiny PCB motors are a great example of this geometry. While those can be completely printed, they’re far from optimal. So, [Carl] started looking at ways to make a radial-flux PCB motor. His design has six six-layer PCB coils soldered perpendicular to a hexagonal end plate. The end plate has traces to connect the coils in a star configuration, and together with a matching top plate, they provide support for tiny bearings. The rotor meanwhile is a 3D-printed cube with press-fit neodymium magnets. Check out the build in the video below.

Connected to an ESC, the motor works decently, but not spectacularly. [Carl] admits that more tweaking is in order, and we have little doubt he’ll keep optimizing the design. We like the look of this, and we’re keen to see it improved.

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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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Magnetic Attraction Of Microduino MCookie Modules

We’ve seen countless different robot kits promoted for STEM education, every one of which can perform the robotic “Hello World” task of line following. Many were in attendance at Maker Faire Bay Area 2019 toiling in their endless loops. Walking past one such display by Microduino, Inc. our attention was caught by a demonstration of their mCookie modules in action: installing a peripheral module took less than a second with a “click” of magnets finding each other.

Many Arduino projects draw from an ecosystem of Arduino shields. Following that established path, Microduino had offered tiny Arduino-compatible boards and peripherals which connected with pins and headers just like their full-sized counterparts. Unfortunately their tiny size also meant their risk of pin misalignment and corresponding damage would be higher as well. mCookie addresses this challenge by using pogo pins for electrical contacts, and magnets to ensure proper alignment. Now even children with not-quite-there-yet dexterity can assemble these modules, opening up a market to a younger audience.

Spring loaded electric connections are a popular choice for programming jigs, and we’ve seen them combined with magnets for ideas like modular keyboards, and there are also LittleBits for building simple circuits. When packaged with bright colorful LEGO-compatible plastic mounts, we have the foundation of an interesting option for introductory electronics and programming. Microduino’s focus at Maker Faire was promoting their Itty Bitty Buggy, which at $60 USD is a significantly more affordable entry point to intelligent LEGO creations than LEGO’s own $300 USD Mindstorm EV3. It’ll be interesting to see if these nifty mCookie modules will help Microduino differentiate themselves from other LEGO compatible electronic kits following a similar playbook.