Neopixels? Try Liquid Nitrogen To Color Shift Your LEDs Instead

If you’re like us, you’ve never spent a second thinking about what happens when you dunk an ordinary LED into liquid nitrogen. That’s too bad because as it turns out, the results are pretty interesting and actually give us a little bit of a look at the quantum world.

The LED fun that [Sebastian] over at Baltic Lab demonstrates in the video below starts with a bright yellow LED and a beaker full of liquid nitrogen. Lowering the powered LED into the nitrogen changes the color of the light from yellow to green, an effect that reverses as the LED is withdrawn and starts to warm up again. There’s no apparent damage to the LED either, although we suppose that repeated thermal cycles might be detrimental at some point. The color change is quite rapid, and seems to also result in a general increase in the LED’s intensity, although that could be an optical illusion; our eyes are most sensitive in the greenish wavelengths, after all.

So why does this happen? [Sebastian] goes into some detail about that, and this is where quantum physics comes into it. The color of an LED is a property of the bandgap of the semiconductor material. Bandgap is just the difference in energy between electrons in the valence band (the energy levels electrons end up at when excited) and the conduction band (the energy levels they start at.) There’s no bandgap in conductive materials — the two bands overlap — while insulators have a huge bandgap and semiconductors have a narrow gap. Bandgap is also dependent on temperature; it increases with decreasing temperature, with different amounts for different semiconductors, but not observably so over normal temperature ranges. But liquid nitrogen is cold enough for the shift to be dramatically visible.

We’d love to see the color shift associated with other cryogens, or see what happens with a blue LED. Want to try this but don’t have any liquid nitrogen? Make some yourself!

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Big Chemistry: Liquefied Natural Gas

The topic of energy has been top-of-mind for us since the first of our ancestors came down out of the trees looking for something to eat that wouldn’t eat them. But in a world where the neverending struggle for energy has been abstracted away to the flick of a finger on a light switch or thermostat, thanks to geopolitical forces many of us are now facing the wrath of winter with a completely different outlook on what it takes to stay warm.

The problem isn’t necessarily that we don’t have enough energy, it’s more that what we have is neither evenly distributed nor easily obtained. Moving energy from where it’s produced to where it’s needed is rarely a simple matter, and often poses significant and interesting engineering challenges. This is especially true for sources of energy that don’t pack a lot of punch into a small space, like natural gas. Getting it across a continent is challenging enough; getting it across an ocean is another thing altogether, and that’s where liquefied natural gas, or LNG, comes into the picture.

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Hackaday Links: October 23, 2022

There were strange doings this week as Dallas-Forth Worth Airport in Texas experienced two consecutive days of GPS outages. The problem first cropped up on the 17th, as the Federal Aviation Administration sent out an automated notice that GPS reception was “unreliable” within 40 nautical miles of DFW, an area that includes at least ten other airports. One runway at DFW, runway 35R, was actually closed for a while because of the anomaly. According to GPSjam.org — because of course someone built a global mapping app to track GPS coverage — the outage only got worse the next day, both spreading geographically and worsening in some areas. Some have noted that the area of the outage abuts Fort Hood, one of the largest military installations in the country, but there doesn’t appear to be any connection to military operations. The outage ended abruptly at around 11:00 PM local time on the 19th, and there’s still no word about what caused it. Loss of GPS isn’t exactly a “game over” problem for modern aviation, but it certainly is a problem, and at the very least it points out how easy the system is to break, either accidentally or intentionally.

In other air travel news, almost as quickly as Lufthansa appeared to ban the use of Apple AirTags in checked baggage, the airline reversed course on the decision. The original decision was supposed to have been based on “an abundance of caution” regarding the potential for disaster from its low-power transmitters, or should a stowed AirTag’s CR2032 battery explode. But as it turns out, the Luftfahrt-Bundesamt, the German civil aviation authority, agreed with the company’s further assessment that the tags pose little risk, green-lighting their return to the cargo compartment. What luck! The original ban totally didn’t have anything to do with the fact that passengers were shaming Lufthansa online by tracking their bags with AirTags while the company claimed they couldn’t locate them, and the sudden reversal is unrelated to the bad taste this left in passengers’ mouths. Of course, the reversal only opened the door to more adventures in AirTag luggage tracking, so that’s fun.

Energy prices are much on everyone’s mind these days, but the scale of the problem is somewhat a matter of perspective. Take, for instance, the European Organization for Nuclear Research (CERN), which runs a little thing known as the Large Hadron Collider, a 27-kilometer-long machine that smashes atoms together to delve into the mysteries of physics. In an average year, CERN uses 1.3 terawatt-hours of electricity to run the LHC and its associated equipment. Technically, this is what’s known as a hell of a lot of electricity, and given the current energy issues in Europe, CERN has agreed to shut down the LHC a bit early this year, shutting down in late November instead of the usual mid-December halt. What’s more, CERN has agreed to reduce usage by 20% next year, which will increase scientific competition for beamtime on the LHC. There’s only so much CERN can do to reduce the LHC’s usage, though — the cryogenic plant to cool the superconducting magnets draws a whopping 27 megawatts, and has to be kept going to prevent the magnets from quenching.

And finally, as if the COVID-19 pandemic hasn’t been weird enough, the fact that it has left in its wake survivors whose sense of smell is compromised is alarming. Our daily ritual during the height of the pandemic was to open up a jar of peanut butter and take a whiff, figuring that even the slightest attenuation of the smell would serve as an early warning system for symptom onset. Thankfully, the alarm hasn’t been tripped, but we know more than a few people who now suffer from what appears to be permanent anosmia. It’s no joke — losing one’s sense of smell can be downright dangerous; think “gas leak” or “spoiled food.” So it was with interest that we spied an article about a neuroprosthetic nose that might one day let the nasally challenged smell again. The idea is to use an array of chemical sensors to stimulate an array of electrodes implanted near the olfactory bulb. It’s an interesting idea, and the article provides a lot of fascinating details on how the olfactory sense actually works.

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Hackaday Links: August 29, 2021

If you thought that COVID-19 couldn’t possibly impact space travel, think again. The ongoing pandemic is having unexpected consequences for companies like SpaceX, who are worried about liquid oxygen shortages due to increased demand for medical oxygen. Massive amounts of liquid oxygen are used as the oxidizer for each rocket launch, of course, as well as in hospitals, which have giant tanks of liquid oxygen somewhere on site. Whether destined for space or for patient care, liquid oxygen comes from cryogenic separation plants, and SpaceX fears that they would have to delay or even cancel launches if manufacturers can’t keep up with demand and have to prioritize their healthcare customers. We’re actually not sure if this is a concern, though, since there are usually separate supply chains for medical and industrial gasses. Then again, we’d suspect a rocket engine might prefer to breathe ultra-pure LOX too.

Speaking of space, if you want to be an astronaut, perhaps the first skill you need to develop is patience. Not only might your ride not be ready to go when you are, but at least in the EU, you’ve got a long line of applicants in front of you. The European Space Agency announced this week that they’re working through a backlog of 23,000 applications for astronaut positions. About 20% of those will apparently be dropped in the pre-screening process, but the rest will (eventually) get an invitation to a full-day test at one of the ESA’s facilities. We imagine the attrition rate from there increases dramatically; either that or the ESA intends to hire a lot of astronauts.

Back here on Earth, Google this week did what it seems to do a lot of, and killed off one of its popular apps. This time the victim is the Android Auto phone app, although we have to admit the whole thing is confusing. The app allows you to connect your phone to the infotainment system in a compatible late-model car, letting you access all your apps without having to fiddle with your phone while driving. But Google also had an app that offered the same experience directly on the phone, for cars without a compatible display. As far as we can tell, the on-phone app is the only thing that’s going away in Android 12; the app for in-car displays will continue to be supported. Former users of the phone-only app are being encouraged to migrate to Google Assistant’s Driving Mode. Or, you know, you could just drive the car instead.

So your brand-new video card is running hot, and you can’t figure out why. At your wit’s end, you crack open the card’s cover and find the reason — a somewhat suspicious-looking foreign object. That’s what happened to Antony ter Horst and his Nvidia RTX 3090, which had a finger cot wedged inside it. It would appear to have slipped off the finger of some assembly worker, and it was clearly interfering with heat flow inside the card. Antony posted the pictures on reddit, which of course found much humor in the finger cot’s resemblance to another latex object. For our part, it put us in mind of some other stories of foreign objects found in common products — there’s a reason why we always check a loaf of bread before using it.

And finally, in a lot of ways YouTube has become the new “vast wasteland” of useless content. But like television before it, there are occasional gems to be found, especially to those of us who love to learn a little something as we watch. And so when we stumbled upon a video with the title “Hot Tap and Stopple Bypass at Smoky Lake” we had to check it out just to find out what each of those words meant. It turned out to be a great video on pipeline construction methods. The “hot tap” refers to cutting into the pipeline, containing high-pressure diluted bitumen from the shale oil fields near Smoky Lake, Alberta, without interrupting the flow of product. The “stopple” is a device that can be threaded into the pipe to permanently seal it, diverting the flow to a newly installed bypass. The whole process is fascinating, so we thought we’d share. Enjoy.

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The WISE In NEOWISE: How A Hibernating Satellite Awoke To Discover The Comet

Over the last few weeks the media has been full of talk about NEOWISE, one of the brightest and most spectacular comets to ever pass through our solar system that you can still see if you hurry. While the excitement over this interstellar traveler is more than justified, it’s also an excellent opportunity to celebrate the Wide-field Infrared Survey Explorer (WISE) space telescope it was named after. The discovery of this particular comet is just the latest triumph in the orbiting observatory’s incredible mission of discovery that’s spanned over a decade, with no signs of slowing down anytime soon.

In fact, WISE has been operational for so long now that its mission has evolved beyond its original scope. When it was launched in December 2009 from California’s Vandenberg Air Force Base, its primary mission was scheduled to be completed in less than a year. But like many NASA spacecraft that came before it, WISE achieved its original design goals and found itself ready for a new challenge. Though not before it spent almost three years in hibernation mode as the agency decided what to do with it.

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Hackaday Podcast 035: LED Cubes Taking Over, Ada Vanquishes C Bugs, Rad Monitoring Is Hot, And 3D Printing Goes Full 3D

Hackaday Editors Mike Szczys and Elliot Williams get caught up on the most interesting hacks of the past week. On this episode we take a deep dive into radiation-monitor projects, both Geiger tube and scintillator based, as well as LED cube projects that pack pixels onto six PCBs with parts counts reaching into the tens of thousands. In the 3D printing world we want non-planar printing to be the next big thing. Padauk microcontrollers are small, cheap, and do things in really interesting ways if you don’t mind embracing the ecosystem. And what’s the best way to read a water meter with a microcontroller?

Take a look at the links below if you want to follow along, and as always tell us what you think about this episode in the comments!

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (60 MB or so.)

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Reducing Drill Bit Wear The Cryogenic Way

There are a lot of ways that metals can be formed into various shapes. Forging, casting, and cutting are some methods of getting the metal in the correct shape. An oft-overlooked aspect of smithing (at least by non-smiths) is the effect of temperature on the final characteristics of the metal, such as strength, brittleness, and even color. A smith may dunk a freshly forged sword into a bucket of oil or water to make the metal harder, or a craftsman with a drill bit might treat it with an extremely cold temperature to keep it from wearing out as quickly.

Welcome to the world of cryogenic treatment. Unlike quenching, where a hot metal is quickly cooled to create a hard crystal structure in the metal, cryogenic treatment is done by cooling the metal off slowly, and then raising it back up to room temperature slowly as well. The two processes are related in that they both achieve a certain amount of crystal structure formation, but the extreme cold helps create even more of the structure than simply tempering and quenching it does. The crystal structure wears out much less quickly than untreated steel, therefore the bits last much longer.

[Applied Science] goes deep into the theory behind these temperature treatments on the steel, and the results speak for themselves. With the liquid nitrogen treatments the bits were easily able to drill double the number of holes on average. The experiment was single-blind too, so the subjectivity of the experimenter was limited. There’s plenty to learn about heat-treated metals as well, even if you don’t have a liquid nitrogen generator at home.

Thanks to [baldpower] for the tip!

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