neodymium

39 Articles

The Diaphragm Is The Coil In These Flexible PCB Speakers

September 21, 2018 by 10 Comments

Speakers used to be largish electromechanical affairs, with magnets, moving coils, and paper cones all working together to move air around in a pleasing way. They’ve gotten much smaller, of course, small enough to screw directly into your ears or live inside the slimmest of smartphones and still delivery reasonable sound quality. The basic mechanism hasn’t changed much, but that doesn’t mean there aren’t other ways to make transduce electrical signals into acoustic waves.

Take these speakers made from flexible printed circuit boards, for instance. While working on his flexible PCB soft actuators, [Carl Bugeja] noticed that the PWM signals coursing through the coils on the thin PCB material while they were positioned over a magnet made an audible beeping. He decided to capitalize on that and try to make a decent speaker from the PCBs. An early prototype hooked to a simple amplifier showed promise, so he 3D-printed a ring to support the PCB like a diaphragm over a small neodymium magnet. The sound quality was decent, but the volume was low, so [Carl] experimented with a paper cone attached to the PCB to crank it up a bit. That didn’t help much, but common objects acting as resonators seemed to work fairly well. Check out the results in the video below.

This is very much a work in progress, but given [Carl]’s record with PCB creations from robotic fish to stepper motors built right into the PCB, we’d say he’ll make substantial improvements. Follow his and others’ progress in the Musical Instruments Challenge part of the 2018 Hackaday Prize.

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Beverage Holder Of Science

July 17, 2018 by 8 Comments

The folks at [K&J Magnetics] have access to precise magnetometers, a wealth of knowledge from years of experience but when it comes to playing around with a silly project like a magnetic koozie, they go right to trial and error rather than simulations and calculations. Granted, this is the opposite of mission-critical.

Once the experimentation was over, they got down to explaining their results so we can learn more than just how to hold our beer on the side of a toolbox. They describe three factors related to magnetic holding in clear terms that are the meat and bones of this experiment. The first is that anything which comes between the magnet and surface should be thin. The second factor is that it should be grippy, not slippy. The final element is to account for the leverage of the beverage being suspended. Say that three times fast.

Magnets are so cool for anything from helping visualize gas atoms, machinists’ tools, and circumventing firearm security features.

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A Brushless Motor On A PCB, Made From PCB

March 28, 2018 by 33 Comments

At Hackaday, we really appreciate it when new projects build on projects we’ve featured in the past. It’s great to be able to track back and see what inspires people to pick up someone else’s work and bring it to the next level or take it down a totally new path.

This PCB brushless motor is a great example of the soft collaboration that makes the Hackaday community so powerful. [bobricius] says he was inspired by this tiny PCB BLDC when he came up with his design. His write-up is still sparse at this point, but it looks like his motor is going to be used to drive a small robot. As with his inspiration, this motor has the stator coils etched right into the base PCB. But there are some significant improvements, like increasing the stator coil count from six to eight, as well as increasing the overall size of the motor. [bobricius] has also done away with the 3D-printed rotor of the original, opting to fabricate his rotor from stacked PCBs with cutouts for 5-mm neodymium magnets. We like the idea of using the same material throughout the motor, and it also raises the potential for stacking a second stator on the other side of the rotor, which might help mechanically and electrically. Even still, the prototype seems to hold its own in the video below.

This is [bobricius]’ second entry in the 2018 Hackaday Prize so far, after his not-a-Nixie tube display. Have you entered anything yet? Get to it! Prizes, achievements, and glory await.

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Print A Sacrificial Magnet Square

January 2, 2018 by 15 Comments

Here’s your quick and dirty hack for the day. Sometimes you just need something that will work for what you’re trying to do, and you don’t want to go through the motions of doing what’s prescribed. When this happens, it’s a cheap, disposable tool that fits the bill. No, we’re not talking about Harbor Freight—we mean those need-driven tools you make yourself that get the job done without fuss. If you’re really lucky, you can use them a couple of times before they break.

This is one of those tools. [Jake’s Workshop] wanted to be able to quickly tack a corner weld without getting out the clamps, so he thought, why not print some magnet squares? [Jake] hollowed out the triangle to save filament, but this also gives it a nice advantage over store-bought magnet squares: instead of grasping and pulling it off,  you can hook your finger through it and then hang it on the pegboard for next time.

[Jake] got lucky with the pocket sizes and was able to press fit the magnets in place, but it would be worth it to add a drop of CA glue to help with strain. He seems to have forgotten to upload the files for his various styles, but a hollow triangle with chamfers and magnet pockets should be easy enough to replicate in OpenSCAD or  SolidWorks, which he used in the video below.

There’s something special about a cheap tool you make yourself. Even though you know it won’t last forever, it’s just more meaningful than some cheap, rage-inducing tchotchke or assemblage from a place where the air is ~85% offgasses. We love necessity-driven self-built tools around here so much that we gave them their own Hacklet.

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Electromagnet-Powered Pendulum

December 30, 2017 by 44 Comments

We’re always happy to see hackers inspired to try something different by what they see on Hackaday. To [SimpleTronic] has a project that will let you stretch your analog electronics skills in a really fun way. It’s an electromagnet pendulum analog circuit. Whether you’re building it, or just studying the schematics, this is a fun way to brush up on the non-digital side of the craft.

The pendulum is a neodymium magnet on the head of a bolt, dangling on a one foot aluminium chain. Below, a Hall Effect sensor rests atop an electromagnet — 1″ in diameter, with 6/8″ wire coiled around another bolt. As the pendulum’s magnet accelerates towards the electromagnet’s core, the Hall effect sensor registers an increase in voltage. The voltage peaks as the pendulum passes overhead, and as soon as the Hall Effect sensor detects the drop in voltage, the electromagnet flicks on for a moment to propel the pendulum away. This circuit has a very low power consumption, as the electromagnet is only on for about 20ms!

The other major components are a LM358N op-amp, a CD4001B quad CMOS NOR gate, and IRFD-120 MOSFET. [SimpleTronic] even took the time to highlight each part of the schematic in order to work through a complete explanation.

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Low-Power Motor Can Run For Years On A Coin Cell

December 25, 2017 by 29 Comments

Can you run an electric motor for two years on a single lithium coin cell? [IamWe] figured out how to do it, and even though his donut motor doesn’t look like any motor we’ve ever seen before, it’s a pretty solid lesson in low-current design.

The donut motor is really just a brushless DC motor with a sign-pole stator and a multi-pole rotor. The frame of the motor is built from a styrofoam donut, hence the motor’s name. The rotor is a styrofoam sphere with neodymium magnets embedded around its equator. A sharpened bicycle spoke serves as an axle, and clever magnetic bearings provide near-zero friction rotation. The stator coil comes from an old solenoid and is driven by a very simple two-transistor oscillator. [IamWe]’s calculations show that the single CR2032 coin cell should power this motor for over two years. This one looks easy enough to whip up that it might make a nice project for a long winter’s night. Watch it spin in the video below.

This one seems like a perfect entry for the Coin Cell Challenge contest. Sure, it may not be a coin cell jump starter for your car, but our guess is this motor will still be spinning in 2020, and that’s no mean feat.

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Over-Engineered Mailbox Flag Machined Using Under-Engineered Mini-Lathe

October 3, 2017 by 55 Comments

[Tim Nummy] used his cheap, Chinese, bench mini-lathe to make a non-terrible mailbox flag holder (YouTube video, embedded below). Tim posts videos on his channel about garage hobby projects, many of which are built using his mini-lathe, often based on suggestions from his followers. One such suggestion was to do something about his terrible mailbox flag – we’re guessing he receives a lot of old-school fan mail.

He starts off by planning the build around 1 ¼ inch aluminum bar stock, a 688 bearing, three neodymium magnets and some screws. The rest of it is a “think and plan as you go along” project, but essentially, the new holder is in three pieces. An inner piece goes inside the mail box and holds the assembly to the mail box. The middle piece holds the two magnets which act as end-stops or limits for the flags raised and lowered positions. The final, outer piece holds the flag itself, and the bearing which allows it to rotate freely.

This part also has the third magnet embedded in it to work with the other two magnets for the limits. The use of magnets is cool, but a ball catch with two detents would have worked just as well. It’s a great simple project to follow for those who want to wet their feet on lathe work. [Tim] has also posted links to all of the tools and equipment seen in the video, so check that out if anything catches your fancy.

But workshop veterans will almost certainly cringe at several places along the video. The main one that caught our eye is obviously the shaky lathe itself. It could do with a heavier workbench, proper leveling, foundation bolts or anti-vibration mounts. And from the looks of it, the tail stock isn’t any rock steady too. Although the lathe is variable speed, the chuck rpm is set too high for aluminum, and the lack of cutting fluid makes it even more troublesome. Using oil, or even some cutting fluid, while tapping would have been wise too.

We’re not sure if it’s the shaky foundation or poor feed control, but the step cut for mounting the bearing is over-sized by a whole lot more and requires a big goop of retaining compound to glue the bearing in place. But the end result works quite well, including the magnetic catches – a complex solution for a simple problem.

We’re sure our keen-eyed readers will likely spot some more issues in [Tim]’s methods, so go at it in the comments below, but please make sure to rein in the snark and keep your feedback positive.

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