OpenEMS Makes Electromagnetic Field Solving… Merely Difficult

July 28, 2017 by 21 Comments

To ordinary people electronics is electronics. However, we know that the guy you want wiring your industrial furnace isn’t the guy you want designing a CPU. Neither of those guys are likely to be the ones you want building an instrumentation amplifier. However, one of the darkest arts of the electronic sects is dealing with electromagnetic fields. Not only is it a rare specialty, but it requires a lot of high-powered math. Enter OpenEMS, a free and open electromagnetic field solver.

We would like to tell you that OpenEMS makes doing things like antenna analysis easy. But that’s like saying Microsoft Word makes it easy to write a novel. In one sense, yes, but you still need to know what you are doing. In fairness, though, the project does provide a good set of tutorials, ranging from a simple wave guide to a sophisticated phased array of patch antennas. Our advice? Start with the waveguide and work your way up from there.

The software uses Octave or MATLAB for scripting, plotting, and support. You can download it for Windows or Linux.

If you want to start with something more intuitive for electromagnetic field visualization, this might help. If you prefer your models more concrete and less abstract, perhaps you should work at Lincoln Lab.

Heavy Lift Electromagnet From Microwave Oven Transformers

January 15, 2017 by 41 Comments

It’s OK, you can admit it — from the time you first saw those huge electromagnetic cranes in scrap yards you’ve wanted to have one. While it may not fling around a car, parts donated from scrapped microwaves can let you build your own electromagnetic lifting device and make that dream finally come true.

We recently watched [MakeItExtreme] turn a couple of microwave oven transformers into a somewhat ill-advised wall-climbing rig. It looks like that may have been the inspiration for this build, and the finished product appears to be a tad more useful this time. The frames of three MOTs are cut open to remove the secondary coils and leave the cores exposed as poles for the future magnets. A shallow dish is fabricated out of steel and the magnets are welded in place.

With the primaries wired together, the magnets are epoxy potted, the business end is faced off cleanly, and the whole thing put to the test. [MakeItExtreme] doesn’t go into control details in the video below, but the website mentions the magnet being powered off a 24V 15A power supply with battery backup in case of mains failure.

They’ve lifted 200kg so far, and it looks like a pretty cool addition to a shop already packed with other builds, like their MOT spot welder and a propane tank sandblaster.

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Toshiro Kodera: Electromagnetic Gyrotropes

January 4, 2017 by 12 Comments

We’ve learned a lot by watching the talks from the Hackaday Superconferences. Still, it’s a rare occurrence to learn something totally new. Microwave engineer, professor, and mad hacker [Toshiro Kodera] gave a talk on some current research that he’s doing: replacing natural magnetic gyrotropic material with engineered metamaterials in order to make two-way beam steering antennas and more.

If you already fully understood that last sentence, you may not learn as much from [Toshiro]’s talk as we did. If you’re at all interested in strange radio-frequency phenomena, neat material properties, or are just curious, don your physics wizard’s hat and watch his presentation. Just below the video, we’ll attempt to give you the Cliff’s Notes.

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Electromagnetic Pulse: Pure Hollywood?

October 18, 2016 by 61 Comments

Imagine you’re in charge of a major heist. Right as your crew is about to rob the main vault, you need all of the electronics in the building to fail at exactly the right moment with no other collateral damage (except, maybe, to your raggedy panel van). Obviously you will turn to one of the entertainment industry’s tired tropes, the electromagnetic pulse! The only problem is that if you were to use a real one rather than a Hollywood prop either there would be practically no effect, a large crater where the vault used to be, or most of humanity would be in deep trouble. After all, the real world isn’t quite as convenient as the movies make it seem.

emp-electromagnetic-pulse-jra-1cg_wq4mp4-shot0001Our curiosity into this phenomenon was piqued when we featured an “EMP generator” from [FPS Weapons]. The device doesn’t create an enrapturing movie-esque EMP pulse suitable for taking down a casino or two, but it does spew a healthy amount of broadband electromagnetic interference (EMI) in every direction. It probably also doesn’t send the EMI very far; as we’ve seen in many other projects, it’s hard to transfer energy through the air. It got us wondering, though: what is the difference between being annoying and creating a weapon? And, is there any practical use for a device like this?

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Coil Gun For Newbies: Learning Electromagnetic Propulsion

August 19, 2016 by 25 Comments

There’s something attractive about coil guns, especially big ones. It’s probably the danger; between the charge stored in banks of capacitors and the flying projectiles, big coil guns can be lethal to experiment with. But there is a lot to be learned from how coil guns work, especially if you build this 3D-printed entry-level coil gun.

For the coil gun newbie, [Great Scott] does a fantastic job of explaining the basics. Pulsing the coil at just the right time will suck a ferromagnetic projectile into the coil core and let momentum fling it out, and multiple coils used correclty improve performance.

His gun is a simple pistol design with two coils, optical sensors to tell when the projectile is centered in each coil, and an Arduino to coordinate everything. The results are not spectacular — he uses only a modest amount of current — but the gun still works. [Great Scott] points out how a capacitor bank could be used to increase the current, but for the sake of keeping it simple he leaves that as an exercise for the builder.

Many coil gun and rail gun builds have made it to our pages over the years, including his ridiculously powerful gun that uses a capacitor bank so large it needs its own car. We like this build for its simplicity, its approachability, and the excellent explanation of its function.

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Electromagnetic Field’s Badge Hanging In The Balance

May 18, 2016 by 5 Comments

Making conference badges is a tough job. Unless you’re sitting on a gold mine, you have to contact a whole bunch of sponsors for help, work the parts that you can get into a coherent design, and do it all on the quick for a large audience. The EMF team is this close to getting it done, but they need some sponsorship for the assembly. If you know anyone, help them out! If they can’t line something up in the next two weeks, they’ll have to pull the plug on the badge entirely.

Electromagnetic Field is a summer-camp hacker convention / festival that takes place in England and is now in its third iteration. As with other big cons, the badge is a good part of the fun.

The 2016 EMF badge looks to be amazing. It’s powered by an ST STM32L4 low-power micro, a color LCD screen, a TI CC3100 WiFi radio module onboard, and a ridiculous number of other features including a gyro and magnetometer, and a giant battery. It’s also a testbed for the brand-new MicroPython, which aims to bring everyone’s favorite scripting language to embedded processors. In fact, they’ve largely built the MicroPython WiFi drivers for the badge.

If they can’t get a sponsor, all is not lost because everything is open source. We’ll all reap the benefits of their hard work. But that’s not the point. The point is that hundreds of hackers will be standing around in a field outside of London without the most audacious badge that we’ve seen designed dangling from their necks.
If you know anyone who can help, get in touch?

Thanks [schneider] for the tip!

Captain America’s Mighty Shield With 7200N Of Powerful Electromagnets!

May 13, 2016 by 57 Comments

At Hackaday, sometimes we nerd out a bit too hard over comic book movies. With Captain America: Civil War in theaters, I knew I had to do a project dedicated to the movie — so I made a ridiculously over powered electromagnet bracer. The hope? To attract a Captain America replica shield from short distances.

electromagnet bracerI had the idea for this project a while ago after watching Avengers: Age of Ultron.

If you’re not familiar, it appears Captain America gets a suit upgrade (presumably from Stark himself) that features some pretty awesome embedded electromagnets allowing him to call his shield back to him from afar.

Now unfortunately, electromagnets aren’t that strong and I knew I wouldn’t be able to achieve quite the same effect as good ol’ CGI — but I’d be darned not to try!  Continue reading “Captain America’s Mighty Shield With 7200N Of Powerful Electromagnets!” →