In a field where components and systems are often known by sterile strings of characters that manufacturers assign or by cutesy names that are clearly products of the marketing department and their focus groups, having your name attached to an innovation is rare. Rarer still is the case where the mere mention of an otherwise obscure inventor’s name brings up a complete schematic in the listener’s mind.
Given how rarely such an honor is bestowed, we’d be forgiven to think that Sidney Darlington’s only contribution to electronics is the paired transistor he invented in the 1950s that bears his name to this day. His long career yielded so much more, from network synthesis theory to rocket guidance systems that would eventually take us to the Moon. The irony is that the Darlington pair that made his name known to generations of engineers and hobbyists was almost an afterthought, developed after a weekend of tinkering.
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If you watch Star Trek, you will know one way to get rid of pesky aliens is to vent antimatter. The truth is, antimatter is a little less exotic than it appears on TV, but for a variety of reasons there hasn’t been nearly as much practical research done with it. There are well over 200 electron accelerators in labs around the world, but only a handful that work with positrons, the electron’s anti-counterpart. [Dr. Aakash Sahai] would like to change that. He’s got a new design that could bring antimatter beams out of the lab and onto the desktop. He hasn’t built a prototype, but he did publish some proof-of-concept simulation work in Physical Review Accelerators and Beams.
Today, generating high-energy positron beams requires an RF accelerator — miles of track with powerful electromagnets, klystrons, and microwave cavities. Not something you are going to build in your garage this year. [Sahai] is borrowing ideas from electron laser-plasma accelerators (ELPA) — a technology that has allowed electron accelerators to shrink to mere inches — and turned it around to create positrons instead.
Continue reading “Creating Antimatter On The Desktop — One Day”
A trebuchet is one of the older machines of war. It’s basically a sling on a frame, with a weight that you can lift up high and which pulls the sling arm over on release. Making one opens up the doors to backyard mayhem, but optimizing one opens up the wonders of physics.
[Tom Stanton] covers just about everything you need to know about trebuchet building in his four-part video series. Indeed, he sums it up in video two: you’ve got some potential energy in the weight, and you want to transfer as much of that as possible to the ball.
This implies that the optimal path for the weight would be straight down, but then there’s the axle in the way. The rest, as they say, is mechanical engineering.
Video three was the most interesting for us. [Tom] already had some strange arm design that intends to get the weight partially around the axle, but he’s still getting low efficiencies, so he builds a trebuchet on wheels — the classic solution. Along the way, he takes a ton of measurements with Physlets Tracker, which does video analysis to extract physical measurements. That tip alone is worth the price of admission, but when the ball tops out at 124 mph, you gotta cheer.
In video four, [Tom] plays around with the weight of the projectile and discovers that he’s putting spin on his tennis ball, making it curve in flight. Who knew?
Anyway, all four videos are embedded below. You can probably skip video one if you already know what a trebuchet is, or aren’t interested in [Tom] learning that paying extra money for a good CNC mill bit is worth it. Video two and three are must-watch trebucheting.
We’re a sad to report that we couldn’t find any good trebuchet links on Hackaday to dish up. You’re going to have to settle for a decade-old catapult post or this sweet beer-pong-playing robotic arm. You can help. Submit your trebuchet tips.
Thanks [DC] for this one!
Continue reading “Trebucheting Tennis Balls at 124 MPH”
Batteries placed in harm’s way need to be protected. A battery placed where a breakdown could endanger a life needs to be protected. Lithium-ion batteries on the bottoms of electric cars are subject to accidental damage and they are bathed in flame-retardant epoxy inside a metal sled. Phone batteries are hidden behind something that will shatter or snap before the battery suffers and warrant inspection. Hoverboard batteries are placed behind cheap plastic, and we have all seen how well that works. Batteries contain chemicals with a high density of energy, so the less exploding they do, the better.
Researchers at Oak Ridge National Laboratory have added a new ingredient to batteries that makes them armored but from the inside. The ingredient is silica spheres so fine it is safe to call it powder. The effect of this dust is that the electrolyte in every battery will harden like cornstarch/water then go right back to being a liquid. This non-Newtonian fluid works on the
principal principle of shear-thickening which, in this case, says that the suspension will become harder as shear force is applied. So, batteries get rock hard when struck, then go back to being batteries when it is safe.
Non-Newtonian fluids are much fun, but we’re also happy to see them put to use. The same principle works in special speed bumps to allow safe drivers to continue driving but jolts speeders. Micromachines can swim in non-Newtonian fluids better than water in some cases.
It was World War II and scientists belonging to the Manhattan Project worked on calculations for the atomic bomb. Meanwhile, in one of the buildings, future Nobel Prize winning theoretical physicist Richard Feynman was cracking the combination lock on a safe because doing so intrigued him. That’s as good a broad summary of Feynman as any: scientific integrity with curiosity driving both his work and his fun.
If you’ve heard of him in passing it may be because of his involvement on the Space Shuttle Challenger disaster commission or maybe you’ve learned something from one of his many lectures preserved on YouTube. But did you know he also played with electronics as a kid, and almost became an electrical engineer?
He was the type of person whom you might sum up by saying that he had an interesting life. The problem is, you have to wonder how he fit it all into one lifetime, let alone one article. We’ll just have to let our own curiosity pick and choose what to say about this curious character.
Continue reading “Richard Feynman: A Life Of Curiosity And Science”
“We want to put water right into your processor.” If that statement makes you sweat, that is good. Sweating is what we’re talking about, but it’s more involved than adding some water like a potted plant. Sweating works naturally by allowing liquid to evaporate, and that phase change is endothermic which is why it feels cool. Evaporative coolers that work in this way, also known as swamp coolers, haven’t been put into computers before because they are full of sloshy water. Researchers in South Korea and the United States of America have been working on an evaporative cooling system mimicking the way some insects keep themselves cool by breathing through their exoskeletons while living in damp soil.
Springtails are little bugs that have to keep the water and air separate, so they don’t drown in the wet dirt where they live. Mother Nature’s solution was for them to evolve to do this with columns that have sharp edges at the exit. Imagine you slowly add water to a test tube, it won’t spill as soon as you reach the top, it will form a dome. This is the meniscus. At a large scale, say a river dam, as soon as you get over the dam you would expect spillage, but at the test tube level you can see a curve. At the scale of the springtail, exuded water will form a globe and resist water pressure. That resistance to water pressure allows this type of water cooling to self-regulate. Those globes provide a lot of surface area, and as they evaporate, they allow more water to replenish the globe. Of course, excessive pressure will turn them into the smallest squirt guns.
We have invented a lot by copying Mother Nature. Velcro was inspired by burrs, and some of our most clever robots copy insects. We can also be jerks about it.
It turns out that curling involves some complex physics. [Destin] of Smarter Every Day has jumped in to find out why scientists on opposite sides of the Atlantic disagree about why curling stones curl.
If you’ve been watching the Olympics, you’ve probably seen some curling, the Scottish sport of competitively pushing stones on ice. As the name implies, curling stones don’t go straight. The thrower pushes them with a bit of rotation, and the stones curve in the direction they are rotating. This is exactly the opposite of what one would expect — try it yourself with an inverted drinking glass on a smooth table. The glass will curl opposite the direction of rotation. Clockwise spin will result in a curl to the left, counterclockwise in a curl to the right.
The cup makes sense when you think about the asymmetrical friction involved. The cup is slowing down, which means more pressure on the leading edge. The rotating leading edge pushes harder against the table and causes the cup to curl opposite the direction of rotation.
Continue reading “The Strange Physics of Curling”