A Scientist Made An Artificial Black Hole In The Lab, And You Won’t Believe What Happened Next

March 8, 2021 by Dan Maloney 53 Comments

OK, that was a little click-baity, but then again, so was the announcement this week that a scientist had confirmed Hawking radiation with a lab-grown black hole. It sure got our attention, at least.

As it turns out, the truth is both less and more than meets the eye. The article above was eventually edited to better reflect the truth that, alas, we have not yet found a way to create objects so massive that even light cannot escape them. Instead, physicist [Jeff Steinhauer] and colleagues at the Technion-Israel Institute of Technology have developed an acoustic model of black holes, which is what was used to observe the equivalent of Hawking radiation for the first time. Hawking radiation is the theoretical exception to the rule that nothing makes it out of a black hole and would imply that black holes evaporate over time. The predicted radiation would be orders of magnitude weaker than the background radiation, though, making it all but impossible to detect.

That’s where [Steinhauer]’s sonic black holes come in. In these experiments, phonons, packets of mechanical vibrations that stand in for photons, are trapped in a fast-moving stream of fluid. The point in the stream where its speed straddles the local speed of sound is the equivalent to a real black hole’s event horizon; phonons inside that boundary can never escape. Except, of course, for the sonic equivalent of Hawking radiation, which the researchers found after 97,000 attempts.

When we first stumbled upon this story, we assumed a lab-grown black hole, even an acoustic analog, would take a CERN’s-worth of equipment to create. It turns out to be far simpler than that; [Steinhauer], in fact, built his black hole machine singlehandedly from relatively simple equipment. The experiments do require temperatures near absolute zero and a couple of powerful lasers, so it’s not exactly easy stuff; still, we can’t help but wonder if sonic black holes are within the reach of the DIY community. Paging [Ben Krasnow] and [Sam Zeloof], among others.

[Featured image credit: Nitzan Zohar, Office of the Spokesperson, Technion]

Sea Level: How Do We Measure Global Ocean Levels And Do Rising Oceans Change That Benchmark?

March 8, 2021 by Adam Zeloof 34 Comments

Every summer you go down the shore, but lately you’ve begun to notice that the beach seems narrower each time you visit. Is that the sea level rising, or is the sand just being swept away? Speaking of sea levels, you keep hearing that they rise higher every year — but how exactly is that measured? After all, you can’t exactly use a ruler. As it turns out, there are a number of clever systems in place that can accurately measure the global sea level down to less than an inch and a half.

Not only are waves always rippling across the ocean’s surface, but tides periodically roll in and out, making any single instantaneous measurement of sea level hopelessly inaccurate. Even if you plan to take hundreds or thousands of measurements over the course of weeks or months, taking the individual measurements is still difficult. Pick a nice, stable rock in the surf, mark a line on it, and return every hour for two weeks to hold a tape measure up to it. At best you’ll get within six inches on each reading, no matter what you’ll get wet, and at worst the rock will move and you’ll get a damp notebook full of useless numbers. So let’s take a look at how the pros do it.

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3D Printing 90° Overhangs With Non-Planar Slicing

March 8, 2021 by Danie Conradie 28 Comments

When slicing a model for 3D printing, the part is divided into a stack of flat, 2D layers. But there’s an alternative in the form of non-planar slicing, where the layers can follow 3D curves. [Rene K. Mueller] took this a step further and successfully used non-planar slicing to print 90° overhangs on a normal Cartesian FDM printer.

Non-planar layers have been around for a while, but were generally limited to creating smooth curves without layer lines. The idea of using the technique for overhangs had been floating around in [Rene]’s head for a while, and he was spurred to action after seeing the rotating tilted nozzle printer featured here on Hackaday. The idea is only to have the outer edge of each layer overhang, by making each layer slope downward toward the overhang. [Rene] programmed a conic slicer algorithm for this purpose, which splits the model into dome-shaped layers, like an onion.

He did a lot of testing and documented the results in detail. Conical slices were compared with tilted slices, which are also used for belt 3D printers. Both have some geometric limitations. Tilted slices can only print the overhang in one direction, but conical slices can do this in all directions, allowing it to create a mushroom-like shape without any support. The limitation is that it can only print inward or outward from a central point. More complex geometry must be segmented, and each sub-volume sliced separately. The slicing angle is also limited by the shape of the print head, to avoid it crashing into the print.

We think this technique has a lot of potential for widespread use, especially since it is compatible with most existing FDM printers. It is still a work in progress, but support has already been added for Slic3r and Prusa Slicer. We look forward to seeing how it develops and gets adopted.

AVR Configurable Custom Logic As A Frequency Divider At 4x Chip’s Clock Speed

March 8, 2021 by Mike Szczys 13 Comments

What a time to be alive when you can find inexpensive microcontrollers that come with programmable(ish) logic that can operate independently of the system clock. [David Johnson-Davies] recently built a proof of concept using the Configurable Custom Logic (CCL) that is available in some of the newer AVR microcontroller designs. It’s a simple implementation, a set of frequency dividers that blink three LEDs with up to a 90 MHz input signal. But the simplicity is the reason to love his write-up — you can wrap your head around it right away.

There are four lookup table (LUTs) used to form the frequency divider. Think of these like a NAND or XOR gate, but you get to decide how the output truth tables will perform. The output is fed into a sequencer which can be configured as a D/JK flip-flop or a D/RS latch, plus you can specify the signal edge, and of course define the clock source. An interesting trick here is to hold the G input of both D flip-flops high by feeding them LUTs set to all ones. Note that the output of the first divider (PA3) is feeding the external input (PD2) of the second divider.

While the CCL is configured using the C code you flash to the microcontroller, it’s a hardware peripheral capable of operating independent of the chip’s system clock. The AVR128DA28 that’s used here tops out at 24 MHz (double that if you use the PLL) but [David] got reliable results from his clock divider feeding a signal as high as 90 MHz to the input pin. Of course you have the option of feeding internal clock signals to the CCL, but that wouldn’t seem nearly as interesting here. For the demo, [David] is actually toggling an IO pin which is connected to PA2 as the external input for the logic. Make sure you click through to his write-up linked above as he does an excellent job of walking through the sample code (just a couple-dozen lines to set this all up). Here’s the datasheet for this chip (PDF, page 447 for pertinent registers) and for a deeper dive the appnote on CCL (PDF).

So what is this all good for? We already saw an answer to that question back in January when [SM6VFZ] used the CCL peripheral to build a software-defined switch-mode converter. How awesome is that?

A Tiny Tube Amp For Not A Lot

March 7, 2021 by Jenny List 49 Comments

At the extreme budget end of tube audio lie single-tube amplifiers usually using very cheap small-signal pentodes. They’ve appeared here before in various guises, and a fitting addition to those previous projects comes from [Kris Slyka]. It’s a classic circuit with a transformer output, and it provides enough amplification to drive a pair of headphones or even a speaker at low levels.

The fairly conventional circuit of the tube amplifier.

Most tube enthusiasts will instantly recognize the anode follower circuit with a transformer in the anode feed through which the output is taken. The tube works in Class A, which means that it’s in its least efficient mode but the one with the least distortion. The transformer itself isn’t an audio part, but a small mains transformer taken from a scrap wall wart. It serves not only for isolation, but also to transform the high impedance output from the tube into a low impedance suitable for driving a headphone or speaker.

The HT voltage is a relatively low 24 V, but it still manages to drive headphones acceptably. Speaker levels require a pre-amp, but even then it’s likely that this circuit is pushing the tube beyond what it’s capable of with a speaker. The more it operates towards the edge of its performance envelope the more distortion it will generate and the worse a sound it will produce. This isn’t such a problem in a guitar application as here, but hi-fi enthusiasts may find it to be too much. It would be interesting to subject it as a headphone amplifier to a series of audio tests to evaluate the effect of a mains transformer over a dedicated audio one.

Last year we took a very in-depth look at the commonly-available Chinese kit pre-amps that use a similar anode-follower circuit but without the transformer. We’ve also seen a similar amp that uses an op-amp as an impedance converter, as well as a novel take on the idea whose unusual biasing allows it to run from only 3.3 volts. These circuits can be so cheap to get started with that we’d suggest anyone give them a try.

Head Lamp Gives Glowing Creature Comforts

March 7, 2021 by Kristina Panos 5 Comments

What can we say? It’s 2021, and we could probably all use a psychotic glow worm lamp in our lives about now to lighten the mood and/or provide a new focal point for sitting and staring. Tired of dragging out that creepy little Elf on the Shelf every holiday season? [LiabilityLabs]’ Head Lamp is slightly less terrifying and far more functional. Really, the options are limitless.

The brain of this scare snake is an Electromage Pixelblaze LED controller, a powerful Wi-Fi enabled little board with a live web editor. [LiabilityLabs] recycled 20 milky plastic containers and their lids to help diffuse the light and avoid hot spots by holding the LED strip in the center of the tube. There’s a momentary button on the glowy guy’s tail that lets [LiabilityLabs] cycle through different color patterns with ease.

Whether you need a mascot for your stream channel, a confidant, or a refreshing rainbow rubber ducky of problem solving, Head Lamp is flexible. Feast your eyes on some brief animations after the break.

Want the glowies without the willies? This mesmerizing fiber optic lamp is an easy build.

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Hackaday Links: March 7, 2021

March 7, 2021 by Dan Maloney 13 Comments

It’s March, which means Keysight is back in the business of giving away a ton of test gear. Keysight University Live starts on March 15, with daily events the first week followed by a string of weekly live events through April. We always enjoy these Keysight events; sure, they’re clearly intended to sell more gear, but the demos and tutorials are great, and we always learn a lot. There’s also a feeling of community that feels similar to the Hackaday community; just a bunch of electronics nerds getting together to learn and share. If you’re interested in that community, or even if you’re just looking for a chance to win something from the $300,000 pile of goodies, you’ll need to register.

There’s another event coming up that you’ll want to know about: the 2021 Open Hardware Summit. Because 2021 is the new 2020, the summit is being held virtually again, this year on April 9. Tickets are on sale now, and we’re told there are still plenty of Ada Lovelace Fellowships available to those who consider themselves to be a minority in tech. The Fellowship covers the full cost of a ticket; it usually covers travels costs too, but sadly we’re still not there yet.

Once we do start traveling again, you might need to plan more carefully if cities start following the lead of Petaluma, California and start banning the construction of gas stations. The city, about 40 miles (64 km) north of San Francisco, is believed to be the first city in the United States to ban new gas station construction. The city council’s decision also prevents gas station owners from expanding, reconstructing, or relocating existing gas stations. The idea is to create incentives to move toward non-fossil fuel stations, like electric vehicle charging stations and hydrogen fueling. Time will tell how well that works out.

Go home Roomba — you’re drunk. That could be what Roomba owners are saying after an update semi-bricked certain models of the robotic vacuum cleaners. Owners noted a variety of behaviors, like wandering around in circles, bumping into furniture, and inability to make its way back to base for charging. There’s even a timelapse on reddit of a Roomba flailing about pathetically in a suspiciously large and empty room. The drunken analogy only goes so far, though, since we haven’t seen any reports of a Roomba barfing up the contents of its dust bin. But we’re still holding out hope.

And finally, if you’re not exactly astronaut material but still covet a trip to space, you might luck out courtesy of Japanese billionaire Yusaku Maezawa. He’s offering to pay the way for eight people from around the world on a planned flight to the Moon and back in 2023. Apparently, Maezawa bought up all the seats for the flight back in 2018 with the intention of flying a group of artists to space. His thinking has changed, though, and now he’s opening up the chance to ~~serve as ballast~~ join the crew to pretty much any rando on the planet. Giving away rides on Starship might be a harder sell after this week’s test, but we’re sure he’ll find plenty of takers. And to be honest, we wish the effort well — the age of routine civilian space travel can’t come soon enough for us.