Science

1440 Articles

The Kilogramme Will Cease To Be A Physical Entity

November 16, 2018 by 72 Comments

One of the most illuminating high school courses no doubt for many readers as much as for your scribe, was the series of physics lessons during which the SI units were explained. That glorious sense of having the order of the universe unlocked into an interlocking series of units whose definitions could all be derived in terms of a series of base units was mind-blowing in those early teen years, and even though the explanations might have been at a for-the-children level that has been blown out of the water by later tiers of learning it’s still a bedrock that will serve an engineer or scientist life-long.

The definitions of the SI base units have evolved with scientific advancement to the point at which they are no longer tied to their original physical entity definitions. Of all the base units though there is still one that has resisted the urge to move away from the physical: the kilogramme (giving it its French spelling to preserve context) is still defined in terms of a metal cylinder in a laboratory just outside Paris. Kg diehards have not much time left to cling onto their platinum-iridium alloy though, for a new definition has been adopted in which it is derived from Planck’s Constant. From next May this will become the official kilogram, at which point concerns over microscopic erosion of the metal standard become irrelevant, and an SI kilogram can be replicated by any laboratory with the means to do so.

The piece of apparatus that makes this definition possible is the Kibble balance, a balance in which the force required to overcome the effect of gravitational force on a given mass is measured in terms of the electrical power required to do so. The gravitational force at a given point can be measured accurately and is defined in terms of the other SI units, while the electrical power can be derived from a Josephson junction, a superconducting junction whose current is defined in terms of Planck’s constant. As a result, the kilogram can be measured solely in terms of the constant and other SI units, consigning the metal cylinder to history.

This high-end metrology and physics make for interesting reading, but it’s fairly obvious that the de facto kilogram we all use will not change. Our everyday measures of everything from sugar to PLA filament will be the same today as they will be next May. But that’s not the point, everyday measurements do not need the extreme accuracy and reproducibility of a laboratory. The point of it all comes in as yet unforseen applications, as an example would the ability to synchronise timing to create GPS or digital radio have been possible were the second to be still defined in terms of astronomical movements rather than atomic states?

Standard kilogramme replica picture: Japs 88 [CC BY-SA 3.0]

Supercon: Designing Your Own Diffractive Optics

November 16, 2018 by 15 Comments

Kelly Peng is an electrical and optical engineer, and founder of Kura AR. She’s built a fusion reactor, a Raman spectrometer, a DIY structured light camera, a linear particle accelerator, and emotional classifiers for likes and dislikes. In short, we have someone who can do anything, and she came in to talk about one of the dark arts (pun obviously intended): optics.

The entire idea of Kura AR is to build an immersive augmented reality experience, and when it comes to AR glasses, there are two ways of doing it. You could go the Google Glass route and use a small OLED and lenses, but these displays aren’t very bright. Alternatively, you could use a diffractive waveguide, like the Hololens. This is a lot more difficult to manufacture, but the payoff will be a much larger field of view and a much more immersive experience.

Continue reading “Supercon: Designing Your Own Diffractive Optics” →

How’s A Gyro Work?

November 15, 2018 by 25 Comments

It wasn’t long ago that a gyro — or gyroscope — was an exotic piece of electronics gear. Most of us only saw them as children’s toys that would balance on your finger. That’s changed, though, thanks to microelectronics. Now your game controller, your phone, and your drone all probably use little ICs that are actually three-axis gyroscopes. Ever wonder how they work and what they do? [RCModelReviews] has a video that covers three kinds of gyros: old mechanical gyros, modern MEMS gyros, and even an exotic laser-based gyro. (YouTube, embedded below.)

Gyroscopes allow you to detect orientation by detecting linear forces on a rotating element. They are used in everything from spacecraft to submarines. The device has many origins dating back to antiquity. But the modern gyro showed up around 1800 or so. The children’s toy appeared in 1917 and is still made today.

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Cyborg Mushrooms

November 15, 2018 by 3 Comments

Of all the fictional cyborgs who turn against humanity to conquer the planet, this is as far from that possibility as you can get. These harmless mushrooms seem more interested in showing off their excellent fashion sense with a daring juxtaposition of hard grid lines with playful spirals. But the purpose of this bacteria-fungus-technology hybrid is to generate electricity. The mushrooms are there to play nurse to a layer of cyanobacteria, the green gel in the photo, while the straight black lines harvest electricity.

Cyanobacteria do not live very long under these kinds of conditions, so long-term use is out of the question, but by giving the cyanobacteria somewhere it can thrive, the usefulness grows. The interplay between bacterial and supportive organics could lead to advances in sensors and hydrogels as well. At some point, we may grow some of our hardware and a green thumb will be as useful as a degree in computer science.

Hydrogels could be the next medical revolution, and we’ve already made hydrogels into tattoos, used them as forms for artificial muscles, and hydrogels can be a part of soft tissue printing.

Pint-sized Jacob’s Ladder Packs 10,000 Volts In A Pickle Jar

November 5, 2018 by 12 Comments

File this one away for your mad scientist costume next Halloween: [bitluni]’s Pocket Jacob’s Ladder is the perfect high voltage accessory for those folks with five dollars in parts, a 3D printer, and very big pockets.

[bitluni]’s video shows you all the parts you’ll need and guides you through the very simple build process. For parts, you’ll require a cheap and readily-available high-voltage transformer, a battery holder, some silver wire for the conductors, and a few other minor bits like solder and a power switch.

Once the electronics are soldered together, they’re stuffed inside a 3d printed case that [bitluni] designed with FreeCAD. The FreeCAD and STL files are all available on Thingiverse. We’re not sure what type of jar [bitluni] used to enclose the electrodes. If your jar isn’t a match, you’ll have to get familiar with FreeCAD or start from scratch with your favorite CAD package.

Either way, we enjoy the slight nod toward electrical safety and the reuse of household objects for project enclosures.

If you’re interested in a Jacob’s Ladder with significantly higher voltage we’ve got you covered, or we’ve also written about another tiny portable Jacob’s Ladder.

The full video is embedded after the break.

Continue reading “Pint-sized Jacob’s Ladder Packs 10,000 Volts In A Pickle Jar” →

Oliver Heaviside: Rags To Recognition, To Madness

October 30, 2018 by 45 Comments

Like any complex topic, electromagnetic theory has its own vocabulary. When speaking about dielectrics we may refer to their permittivity, and discussions on magnetic circuits might find terms like reluctance and inductance bandied about. At a more practical level, a ham radio operator might discuss the impedance of the coaxial cable used to send signals to an antenna that will then be bounced off the ionosphere for long-range communications.

It’s everyday stuff to most of us, but none of this vocabulary would exist if it hadn’t been for Oliver Heaviside, the brilliant but challenging self-taught British electrical engineer and researcher. He coined all these terms and many more in his life-long quest to understand the mysteries of the electromagnetic world, and gave us much of the theoretical basis for telecommunications.

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Failing At Making Ferrofluid

October 26, 2018 by 17 Comments

[NileRed] admits that while ferrofluid has practical uses, he simply wanted to play with it and didn’t want to pay the high prices he found in Canada. A lot of the instructions he found were not for making a true ferrofluid. He set out to create the real thing, but he wasn’t entirely successful. You can see the results — which aren’t bad at all — in the video below.

We’ve always said you learn more from failure than success. The process of creating ferrofluid involves two key steps: creating coated nanoparticles of magnetite and removing particles that are too large or improperly coated. After the first not entirely satisfactory attempt, [NileRed] tried to purify the material using solvents and magnets to create better-quality particles. Even the “bad” material, though, looked fun to play with along with a powerful magnet.

You’ll see that the material is clearly magnetic, it just doesn’t spike like normal ferrofluid. [NileRed] had commercial ferrofluid for testing and found that if he diluted it enough, it behaved like his homemade fluid. So while not conclusive, it seems like he diluted the batch too much.

We hope to see a better batch from him soon. The base material he used for the first patch was homemade — he covers that in a different video. However, for the second batch, he is going to start with commercial ferric chloride — what we know as PCB etchant.

Even though the experiment was not entirely successful, we enjoyed seeing the process and watching the performance of both the homemade batch and the commercial ferrofluid. He’s getting a lot of advice and speculation in the video comments, and it is very possible a Hackaday reader might be able to help, too.

We’ve seen other reports of unsuccessful ferrofluid production. If you need a practical reason to make or buy some, how about a clock?