Be A Fire Bender With The Power Of Magnets

July 23, 2018 by Dan Maloney 26 Comments

More often than you think, scientific progress starts with a simple statement: “Huh, that’s funny…” That’s the sign that someone has noticed something peculiar, and that’s the raw fuel of science because it often takes the scientist down interesting rabbit holes that sometimes lead to insights into the way the world works.

[Ben Krasnow] ended up falling down one of those rabbit holes recently with his experiments with magnets and flames. It started with his look at the Zeeman effect, which is the observation that magnetic fields can influence the spectral lines of light emitted by certain sources. In a previous video, [Ben] showed that light from a sodium lamp could be dimmed by a powerful electromagnet. Some of his viewers took exception to his setup, which used an oxy-acetylene flame doped with sodium passing through the poles of the magnet; they thought the effect observed was a simple magnetohydrodynamic effect, and not the Zeeman effect he was supposed to be testing. That led to the experiments in the video below, which started with a candle flame being strongly deflected by the magnet. [Ben] methodically worked through the problem, eliminating variables by going so far as to blow soap bubbles of various gasses within the magnet’s poles to rule out the diamagnetism of oxygen as a cause of the phenomenon. He finally showed that even hot air by itself is deflected, using a simple light bulb and a FLIR camera. It’s good stuff, and well worth a watch.

Spoiler alert: [Ben] is still scratching his head about what’s going on, and we’re looking forward to his conclusions. This isn’t his first rabbit hole expedition, of course; his experiments with creating plasma with high-pressure water were fascinating, as were his DIY superconducting ceramics. Continue reading “Be A Fire Bender With The Power Of Magnets” →

A 3D-Printed Bowl Feeder For Tiny SMD Parts

July 22, 2018 by Dan Maloney 30 Comments

[Andrzej Laczewski] has something big in mind for small parts, specifically SMD resistors and capacitors. He’s not talking much about that project, but from the prototype 3D-printed bowl feeder he built as part of it, we can guess that it’s going to be a pretty cool automation project.

Bowl feeders are common devices in industrial automation, used to take a big pile of parts like nuts and bolts and present them to a process one at a time, often with some sort of orientation step so that all the parts are the right way around. They accomplish this with a vibratory action through two axes, which [Andrzej] accomplishes with the 3D-printed ABS link arms supporting the bowl. The spring moment of the arms acts to twist the bowl slightly when it’s pulled down by a custom-wound electromagnet, such that the parts land in a slightly different place every time the bowl shifts. For the parts on the shallow ramp spiraling up the inside of the bowl, that means a single-file ride to the top. It’s interesting to see how changing the frequency of the signal sent to the coil impacts the feed; [Andrzej] used a function generator to find the sweet spot before settling on a dedicated circuit. Watch it in action below.

We’re really impressed with the engineering that went into this, even if we wonder what the vibration will do to the SMD components. Still, we can’t wait to see this in a finished project – perhaps it’ll be integrated like this Arduino-fied bowl feeder.

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An Electromagnet Brings Harmony To This Waving Cat

June 1, 2018 by Kerry Scharfglass 9 Comments

We’ve noticed waving cats in restaurants and stores for years, but even the happy bobbing of their arm didn’t really catch our attention. Maybe [Josh] had seen a couple more than we have when it occurred to him to take one apart to see how they work. They are designed to run indoors from unreliable light sources and seem to bob along forever. How do the ubiquitous maneki-neko get endless mechanical motion from one tiny solar cell?

Perhaps unsurprisingly given the prevalence and cost of these devices, the answer is quite simple. The key interaction is between a permanent magnet mounted to the end of the waving arm/pendulum and a many-turn wire coil attached to the body. As the magnet swings over the coil, its movement induces a voltage. A small blob of analog circuitry reacts by running current through the coil. The end effect is that it “senses” the magnet passing by and gives it a little push to keep things moving. As long as there is light the circuit can keep pushing and the pendulum swings forever. If it happens to stop a jolt from the coil starts the pendulum swinging and the rest of the circuit takes over again. [Josh] points to a similar circuit with a very nice write up in an issue of Nuts and Volts for more detail.

We’ve covered [Josh]’s toy teardowns before and always find this category of device particularly interesting. Toys and gadgets like the maneki-neko are often governed by razor-thin profit margins and as such must satisfy an extremely challenging intersection of product constraints, combining simple design and fabrication with just enough reliability to not be a complete disappointment.

For more, watch [Josh] describe his method in person after the break, or try flashing his code to an Arduino and make a waving cat of your own.

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Mechanisms: Solenoids

May 23, 2018 by Dan Maloney 34 Comments

Since humans first starting playing with electricity, we’ve proven ourselves pretty clever at finding ways to harness that power and turn it into motion. Electric motors of every type move the world, but they are far from the only way to put electricity into motion. When you want continuous rotation, a motor is the way to go. But for simpler on and off applications, where fine control of position is not critical, a solenoid is more like what you need. These electromagnetic devices are found everywhere and they’re next in our series on useful mechanisms.

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Play Chess Against A Ghost

April 19, 2018 by Bryan Cockfield 19 Comments

While chess had long been a domain where humans were superior to computers, the balance has shifted quite substantially in the computers’ favor. But the one thing that humans still have control over is the pieces themselves. That is, until now. A group has built a robot that both uses a challenging chess engine, and can move its own pieces.

The robot, from creators [Tim], [Alex S], and [Alex A], is able to manipulate pieces on a game board using a robotic arm under the table with an electromagnet. It is controlled with a Raspberry Pi, which also runs an instance of the Stockfish chess engine to play the game of chess itself. One of the obvious hurdles was how to keep the robot from crashing pieces into one another, which was solved by using small pieces on a large board, and always moving the pieces on the edges of the squares.

This is a pretty interesting project, especially considering it was built using a shoestring budget. And, if you aren’t familiar with Stockfish, it is one of the most powerful chess engines and also happens to be free and open-source. We’ve seen it used in some other chess boards before, although those couldn’t move their own pieces.

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Mechanisms: The Reed Switch

March 1, 2018 by Kristina Panos 75 Comments

Just about everywhere you go, there’s a reed switch nearby that’s quietly going about its work. Reed switches are so ubiquitous that you’re probably never more than a few feet away from one at any given time, especially at home or in the car. You might have them on your doors and windows as part of a burglar alarm system. They keep your washing machine from running when the lid is open, and they put your laptop to sleep when you close the lid. They know if the car has enough brake fluid and whether or not your seat belt is fastened.

Reed switches are interesting devices with a ton of domestic and industrial applications. We call them switches, but they’re also sensors. In fact, they only do the work of a switch while they can sense a magnetic field. They are capable of switching AC or DC at low and high voltages, but they don’t need electricity to work. Since they’re sealed in glass, they are impervious to dirt, dust, corrosion, temperature swings, and explosive environments. They’re cheap, they’re durable, and in low-current applications they can last for about a billion actuations.

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A Stepper Motor For Two Dimensions

January 8, 2018 by Dan Maloney 47 Comments

We’ve all heard linear motors, like those propelling Maglev trains, described as “unrolled” versions of regular electric motors. The analogy is apt and helps to understand how a linear motor works, but it begs the question: what if we could unroll the stator in two dimensions instead of just one?

That’s the idea behind [BetaChecker’s] two-axis stepper motor, which looks like it has a lot of potential for some interesting applications. Build details are sparse, but from what we can gather from the videos and the Hackaday.io post, [BetaChecker] has created a platen of 288 hand-wound copper coils, each of which can be selectively controlled through a large number of L293 H-bridge chips and an Arduino Mega. A variety of sleds, each with neodymium magnets in the base, can be applied to the platen, and depending on how the coils are energized, the sled can move in either dimension. For vertical applications, it looks like some coils are used to hold the sled to the platen while others are used to propel it. There are RGB LEDs inside the bore of each coil, although their function beyond zazzle is unclear.

We’d love more details to gauge where this is going, but with better resolution, something like this could make a great 3D-printer bed. If one-dimensional movement is enough for you, though, check out this linear stepper motor that works on a similar principle.

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