magnets

74 Articles

Pong In Real Life, Mechanical Pong

May 28, 2016 by 43 Comments

[Daniel Perdomo] and two of his friends have been working on a mechanical version of Pong for the past two years. We can safely say that the final result is beautiful. It’s quite ethereal to watch the pixe–cube move back and forth on the surface.

[Daniel] has worked in computer graphics for advertising for more than 20 years. However, he notes that neither he nor his friends had any experience in mechanics or electronics when they began. Thankfully, the internet (and, presumably, sites like Hackaday) provided them with the information needed.

The pong paddles and and pixel (ball?) sit onto of a glass surface. The moving parts are constrained to the mechanics with magnets. Underneath is a construction not unlike an Etch A Sketch for moving the ball while the paddles are just on a rail with a belt. The whole assembly is made from V-groove extrusion.

Our favorite part of the build is the scroll wheel for moving the paddle back and forth. For a nice smooth movement with some mass behind it, what’s better than a hard-drive platter? They printed out an encoder wheel pattern and glued it to the surface. The electronics are all hand-made. The brains appear to be some of the larger Arduinos. The 8-bit segments, rainbow LEDs, etc were build using strips glued in place with what looks like copper foil tape connecting buses. This is definitely a labor of love.

It really must be seen to be understood. The movement is smooth, and our brains almost want to remove a dimension when watching it. As for the next steps? They are hoping to spin it up into an arcade machine business, and are looking for people with money and experience to help them take it from a one-off prototype to a product. Video after the break.

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Hard Drive Disassembly Is Easy And Rewarding

February 3, 2016 by 61 Comments

Have any dead hard drives kicking around? Hackaday alum [Jeremy Cook] shows how easy it is to disassemble a hard drive to scavenge its goodies. The hardest part is having the patience and the tools to get past all those screws that stand between you and the treasure inside.

The case screws are frequently of the Torx variety. Any self-respecting hacker probably has one or two of these already, but if you’re in the market, [Jeremy] recommends a nice set that looks way better than ours. Once the case is open, you can find rare earth magnets, bearings, and one or more platters.

Those terrifically strong magnets are good for all kinds of projects. Glue a couple of them to the back of an attractive piece of wood, mount it on the kitchen wall, and you have yourself a knife block. Keep a couple on the bench to temporarily magnetize tools. Use them to build a pickup to amplify a cigar box guitar or thumb piano. Or run the pickup into a small amplified speaker and wave it like a stethoscope near your electronics to hear them hum. As far as liberating the magnets goes, [Jeremy] resorted to clamping his in a vise and using a hammer and chisel to pry it away from the actuator hardware.

You’ve no doubt seen clocks made from old hard drives that were kept mostly intact. Many makers including [Jeremy] will extract the shiny platters to use as bases for clock faces and engrave the numbers, etch them, or glue them on. Those platters also make excellent chimes. Even if you just hang one platter off of a finger and tap it with a fingernail, it sounds really nice.

If simple chimes don’t really butter your muffin, there are all kinds of sonic projects for dead hard drives. How about making a microphone or speakers? Maybe an HDD MIDI controller or a synthesizer is more your speed. Speaking of synths, watch [Jeremy] take a hard drive apart to some sweet sounds after the break.

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Bismuth Crystals Hold Magnet Suspended For 100 Years

January 25, 2016 by 37 Comments

[NightHawkInLight] has been playing around with the diamagnetic properties of bismuth. Diamagnetic materials get a lot of attention due to their strange ability to produce the opposite of the magnetic field going through them. In simpler terms, metals like iron are attracted to magnets; metals like bismuth repel them.

[NightHawkInLight] built his own interpretation of a common lab example used to demonstrate this remarkable property, a levitator. A levitator is made by sandwiching a magnet between two plates of diamagnetic material. One of the plates is given a magnetic field opposite of the magnet underneath it by a stronger magnet placed some distance away. When this is done, the magnet in between wants to repel away from the plate above, only to find that as it gets closer to the plate below it is equally repelled, creating a stable system.

Eventually the magnet above will need realignment, but [NightHawkInLight] assures us this is only once every 100 years. Video after the break. Continue reading “Bismuth Crystals Hold Magnet Suspended For 100 Years” →

Back To Basics: What’s The Deal With Magnets?

November 20, 2015 by 82 Comments

I consider myself a fairly sharp guy. I’ve made a living off of being a scientist for over 20 years now, and I have at least a passing knowledge of most scientific fields outside my area. But I feel like I should be able to do something other than babble incoherently when asked about magnets. They baffle me – there, I said it. So what do I do about it? Write a Hackaday post, naturally – chances are I’m not the only one with cryptomagnetonescience, even if I just made that term up. Maybe if we walk through the basics together, it’ll do us both some good understanding this fundamental and mysterious force of nature.

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Hacker Reads Magnetic Stripe Card With Flatbed Scanner

August 7, 2015 by 29 Comments

[anfractuosus] has been reading magnetic stripe card… optically!

While hackers routinely read and write stripe cards, this is the first time we’ve reported on optically imaging and decoding data from the magnetic stripe. [anfratuosus] used a magnetic developer which is designed to allow visual inspection of the magnetic stripe. The developer uses micron sized iron particles in a suspension which are dropped onto the stripe. To the particles, the magnetic stripe looks like a series of magnets lined up. Long magnets striperepresent 0s and short magnets 1s. With each bit the orientation of the magnet changes, something like the diagram to the right. The magnetic field is strongest where the poles meet. So the iron particles are attracted to these flux reversal points on the stripe creating a visible pattern . There’s an awesome video of the process in action below.

While magnetic developer was designed for debugging faulty recording systems [anfratuosus] went a step further scanning the “developed” card, and writing a tool to decode the images and extract the card data. [anfratuosus] doesn’t mention any particular application, we love this circuitous hack anyway!

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Make A Microphone Out Of A Hard Drive

July 27, 2015 by 6 Comments

[Rulof Maker] has a penchant for making nifty projects out of old electronics. The one that has caught our eye is  a microphone made from parts of an old hard drive. The drive’s arm and magnet were set aside while  the aluminum base was diagonally cut into two pieces.  One piece was later used to reassemble the hard drive’s magnet and arm onto a wooden platform.

v2_micThe drive’s arm and voice coil actuator are the key parts of this project. It was modified with a metal extension so that a paper cone cut from an audio speaker could be attached, an idea used in microphone projects we’ve previously featured. Copper wire scavenged from the speaker was then soldered to voice coil on the arm as well as an audio jack. In the first version of the Hard Drive Microphone, the arm is held upright with a pair of springs and vibrates when the cone catches sound.

While the microphone worked, [Rulof] saw room for improvement. In the second version, he replaced the mechanical springs with magnets to keep the arm aloft. One pair was glued to the sides of the base, while another pair recovered from an old optical drive was affixed to the arm. He fabricated a larger paper cone and added a pop filter made out of pantyhose for good measure. The higher sound quality is definitely noticeable. If you are interested in more of [Rulof’s] projects, check out his YouTube channel.

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Micro-Scallop Robot

Nanobots Swim Like Scallops In Non-Newtonian Fluids

November 8, 2014 by 12 Comments

The idea of using nanobots to treat diseases has been around for years, though it has yet to be realized in any significant manner. Inspired by Purcell’s Scallop theorem, scientists from the Max Planck Institute for Intelligent Systems have created their own version . They designed a “micro-scallop” that could propel itself through non-Newtonian fluids, which is what most biological fluids happen to be.

The scientists decided on constructing a relatively simple robot, one with two rigid “shells” and a flexible connecting hinge. They 3D-printed a negative mold of the structure and filled it with a polydimethylsiloxane (PDMS) solution mixed with fluorescent powder to enable detection. Once cured, the nanobot measured 800 microns wide by 300 microns thick. It’s worth noting that it did not have a motor. Once the mold was complete, two neodymium magnets were glued onto the outside of each shell. When a gradient-free external magnetic field was applied, the magnets make the nanobot’s shells open and close. These reciprocal movements resulted in its net propulsion through non-Newtonian media. The scientists also tested it in glycerol, an example of a Newtonian fluid. Confirming Purcell’s Scallop theorem, the nanobot did not move through the glycerol. They took videos of the nanobot in motion using a stereoscope, a digital camera with a colored-glass filter, and an ultraviolet LED to make the fluorescent nanobot detectable.

The scientists did not indicate any further studies regarding this design. Instead, they hope it will aid future researchers in designing nanobots that can swim through blood vessels and body fluids.  We don’t know how many years it will be before this becomes mainstream medical science, but we know this much: we will never look at scallops the same way again!

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