magnet

122 Articles

Maybe You Really Can Sense Magnetic Fields

March 23, 2019 by 42 Comments

We’ve known for years that many animals can somehow sense magnetic fields. Birds apparently use the Earth’s magnetic field to navigate. Dogs can find a box containing a magnet better than they can find a similar box with a food treat in it. But humans, apparently, can’t visualize magnetic fields without help. Several scientists at California, New Jersey, and Japan have done experiments that seem to show that people’s brains do have changes when a magnetic field rotates. If the paper, titled “Transduction of the Geomagnetic Field as Evidenced from Alpha-band Activity in the Human Brain” is a bit much for you, might enjoy the video from Veritasium, below, which is much easier to parse than the paper.

To see it work, a subject sits in a dark isolated room with an electrode cap that picks up the subject’s EEG. The study shows that different people have different sensitivity to the field. Also, picking up a magnetic field in an isolated chamber is different from picking it up on the sidewalk and using it to navigate with. Continue reading “Maybe You Really Can Sense Magnetic Fields” →

Flexible PCB Robot Flops Around To Get Around

February 27, 2019 by 4 Comments

In his continuing quest to reduce the parts count of a robot as far as possible, [Carl Bugeja] has hit upon an unusual design: robots built of almost nothing but PCBs.

Admittedly, calling these floppy four-legged critters robots is still a bit of a stretch at this point. The video below shows that while they certainly move under their own power, there’s not a lot of control to the movement – yet. [Carl]’s design uses an incredibly fragile looking upper arm assembly made from FR4. Each arm holds a small neodymium magnet suspended over the center of a flexible PCB coil, quite like those we’ve seen him use before as actuators and speakers. The coils are controlled by a microcontroller living where the four legs intersect. After a few uninspiring tethered tests revealed some problems with the overly compliant FR4 magnet supports, [Carl] made a few changes and upped the frequency of the leg movements. This led to actual motion and eventually to untethered operation, with the bot buzzing around merrily.

There are still issues with the lack of stiffness of the magnet arms, but we’re optimistic that [Carl] can overcome them. We like this idea a lot, and can see all sort of neat applications for flapping and flopping locomotion.

Continue reading “Flexible PCB Robot Flops Around To Get Around” →

Visual Magnetic Fields

February 25, 2019 by 18 Comments

If you need help visualizing magnetic fields, these slow-motion video captures should educate or captivate you. Flux lines are difficult to describe in words, because magnet shape and strength play a part. It might thus be difficult to visualize what is happening with a conical magnet, for a person used to a bar magnet. We should advise you before you watch the video below the break, if you are repelled by the sight of magnetite sand clogging a bare magnet then flying on the floor, this is your only warning.

The technique and equipment are simple and shown in the video. A layer of black sand is spread on a piece of tense plastic to make something like a dirty trampoline, and a neodymium magnet is dropped in the middle. The bouncing action launches the sand and magnet simultaneously so they are hanging in the air and the particles can move with little more than air resistance.

These videos were all taken with a single camera and a single magnet. Multiple cameras would yield 3D visuals, and the intertwining fields of multiple magnets can be beautiful. Perhaps a helix of spherical magnets? What do you have lying around the hosue? In a twist, we can use magnets to simulate gas atoms and trick them into performing unusual feats.

Continue reading “Visual Magnetic Fields” →

Visualizing Eddy Currents

February 19, 2019 by 18 Comments

If [Electroboom] gives up making videos and decides to become a lounge lizard in the Poconos, we hope he adopts the stage name Eddy Currents. However, he is talking about eddy currents in his recent video post that you can see below.

We know he doesn’t really think he can get the magnet to slow down with one sheet of aluminum foil and that he stages at least most of his little electric accidents, but we still enjoy watching it. Meanwhile, he also has a good explanation of why a copper pipe will slow down a magnet and how eddy current affects transformer efficiency.

Continue reading “Visualizing Eddy Currents” →

The Magnetic Rubik’s Cube

February 16, 2019 by 6 Comments

Ernő Rubik has much to answer for when it comes to the legacy of his namesake cube. It has both enthralled and tormented generations, allowing some to grandstand in the playground while others are forced to admit defeat in the face of a seemingly intractable puzzle. It just so happens that [Tom Parker] has been working on a Rubik’s cube with a novel magnetic design.

Yes, that’s right – [Tom]’s cube eschews the traditional rotating and sliding mechanism of the original cube, instead replacing it all with magnets. Each segment of the cube, along with the hidden center piece, is 3D printed. Through using a fused deposition printer, and pausing the print at certain layers, it’s possible to embed the magnets inside the part during the printing process.

[Tom] provides several different versions of the parts, to suit printers of different capabilities. The final cube allows both regular Rubik’s cube movements, but also allows for the player to cheat and reassemble it without having to throw it forcefully against the wall first like the original toy.

It’s an interesting build, and a great one to get to grips with the techniques involved in embedding parts in 3D prints. It may not be capable of solving itself, but we’ve seen another build that can pull off that impressive feat. Video after the break.

Continue reading “The Magnetic Rubik’s Cube” →

Biodegradable Implants Supercharge Nerve Regeneration

February 16, 2019 by 8 Comments

Controlled electrical stimulation of nerves can do amazing things. It has been shown to encourage healing and growth in damaged cells of the peripheral nervous system which means regaining motor control and sensation in a shorter period with better results. This type of treatment is referred to as an electroceutical, and the etymology is easy to parse. The newest kid on the block just finished testing on rat subjects, applying electricity for one, three, or six days per week in one-hour intervals. The results showed that more treatment led to faster healing. The kicker is that the method of applying electricity was done through unbroken skin on an implant that dissolves harmlessly.

The implant in question is, at its most basic, an RFID tag with leads that touch the injured nerves. This means wireless magnetic coupling takes power from an outside source and delivers it to where it is needed. All the traces on are magnesium. There is a capacitor with silicon dioxide sandwiched between magnesium, and a diode made from a doped silicon nanomembrane. All this is encased in a biodegradable substrate called poly lactic-co-glycolic acid, a rising star for FDA-approved polys. Technologically speaking, these are not outrageous.

These exotic materials are not in the average hacker’s hands yet, but citizen scientists have started tinkering with the less invasive tDCS and which is applying a small electrical current to the brain through surface electrodes or the brain hacking known as the McCollough effect.

Via IEEE Spectrum.

Magnets And Printed Parts Make Quick-Disconnect Terminals

November 15, 2018 by 19 Comments

The Apple MagSafe power connector is long gone from their product line, but that doesn’t mean that magnetic connectors aren’t without their charms. It just takes the right application, and finding one might be easier with these homebrew magnetic connectors.

We’ll admit that the application that [Wesley Lee] found for his magnetic connectors is perhaps a little odd. He’s building something called Linobyte, a hybrid art and electronics project that pays homage to computing history with very high-style, interactive core memory modules. The connectors are for the sense wire that is weaved through the eight toroids on each module, to program it with a single byte. Each connector has a 3D-printed boot that holds a small, gold-plated neodymium magnet with the sense wire soldered to it. A socket holds another magnet to the underside of a PCB. The magnet in the boot sticks to the PCB and makes contact with pads, completing the circuit. We know what you’re thinking: heating a magnet past the Curie point is a great way to ruin it. [Wesley] admits that happens, but it just makes the connection a little weaker, which works for his application. The short video below shows how he puts them together.

We can think of a couple of ways these connectors would be useful, and we really like the look of the whole project. It’ll be interesting to see where it goes, but in the meantime, brushing up on how magnets work could be fun. Continue reading “Magnets And Printed Parts Make Quick-Disconnect Terminals” →