Ask Hackaday: What Are Magnetic Gears (Good For)?

Magnetic gears are surprisingly unknown and used only in a few niche applications. Yet, their popularity is on the rise, and they are one of the slickest solutions for transmitting mechanical energy, converting rotational torque and RPM. Sooner or later, you’re bound to stumble upon them somewhere, so let’s check them out to see what they are and what they are good for.

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You May Have a Nixie Tube Clock, but Can Yours Levitate?

Nixie tubes, electromagnets, levitation, and microcontrollers — this project has “Hackaday” written all over it!

Time Flies: Levitating Nixie Clock comes from [Tony Adams], and uses a lot of technology we’ve seen before, but in a new and interesting way. A nixie tube clock is nothing new, but using electromagnets to levitate it above a base certainly paired with inductive coupling to transmit power using no wires make this floating nixie build a real treat.

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Modest Motor Has Revolutionary Applications

Satellites make many of our everyday activities possible, and the technology continues to improve by leaps and bounds. A prototype, recently completed by [Arda Tüysüz]’s team at ETH Zürich’s Power Electronics Systems Lab in collaboration with its Celeroton spinoff, aims to improve satellite attitude positioning with a high speed, magnetically levitated motor.

Beginning as a doctoral thesis work led by [Tüysüz], the motor builds on existing technologies, but has been arranged into a new application — with great effect. Currently, the maneuvering motors on board satellites are operated at a low rpm to reduce wear, must be sealed in a low-nitrogen environment to prevent rusting of the components, and the microvibrations induced by the ball-bearings in the motors reduces the positioning accuracy. With one felling swoop, this new prototype motor overcomes all of those problems.

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Smartphone Hack For Adding Magnet Power Dock

Here’s a neat hack for making a magnetic charging mount for a cell phone. We know what you’re thinking, but this is definitely not a traditional contactless charging system. Those use magnets but in a different way. This hack involves putting a couple of magnets onto the case of the cell phone, and a couple more on a charging base. You then wire these magnets into the power inputs of the USB port, and a USB cable onto the base, so putting the phone on the base magnets completes the circuit. The magnets themselves become the charging contacts.

It’s a neat idea, but makes us wonder what this will do to the compass sensor in your phone or your credit cards if they are nearby. With these caveats, it is a neat hack, and could be easily adapted. Want to make a vertical cell phone mount, or a way to attach (and charge) your cell phone to the fridge? This can be easily adapted for that.

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Hackaday Prize Entry: Visualizing Magnetic Fields

In 1820, Hans Christian Oersted discovered the needle of a compass would deflect when placed next to a wire carrying an electric current. It took 15 years for the first electric motor to be invented following this observation. Humans are dumb, but perhaps they wouldn’t be so oblivious to the basic facts of our reality if they could see magnetic fields. Or if they just had a 3D printer. For his Hackaday Prize entry, [Ted Yapo] is doing just this: adding a magnetic field scanner to a 3D printer, allowing for the visualization of magnetic fields in three dimensions.

The device [Ted] is working on is actually extremely simple, and is mostly implemented in software. The hardware is just a 3D printer with a toolhead consisting of a HMC5883L magnetometer breakout board. This is the simplest and easiest way to find the direction and intensity of a magnetic field, the rest of the work is done in software.

Right now, [Ted] has a setup that will scan a 3D volume with a printer. By placing a magnet in the middle of the print bed, he can visualize the magnetic field inside the volume of his 3D printer. It’s a visualization that is vastly superior to a compass, ferrofluid, or even a mess of iron filings, and is surely a much better pedagogical apparatus for classrooms and science museums alike.

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Pong In Real Life, Mechanical Pong

[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

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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