Wooden You Like To Hear A CNC-Cut Phonograph Record?

Say what you will about [Thomas Edison], but it’s hard to deny the genius of his self-proclaimed personal favorite invention: the phonograph. Capturing sound as physical patterns on a malleable medium was truly revolutionary, and the basic technology that served as the primary medium of recorded sound for more than a century and built several major industries is still alive and kicking today.

With so much technological history behind it, what’s the aspiring inventor to do when the urge to spin your own phonograph records strikes? Easy — cut them from wood with a CNC router. At least that’s how [alnwlsn] rolled after the “one-percent inspiration” hit him while cutting a PCB with his router. Reasoning that the tracks on the copper were probably about as fine as the groove on a record, he came up with some math to describe a fine-pitch spiral groove and overlay data from a sound file, and turn the whole thing into G-code.

For a suitable medium, he turned to the MDF spoil board used to ship PCB stencils, which after about three hours of milling resulted in a rather hairy-looking 78-RPM record. Surprisingly, the record worked fairly well on a wind-up Victrola. The spring-powered motor was a little weak for the heavy wooden record and needed a manual assist, but you can more or less clearly hear the 40-second recording. Even more surprising was how much better the recording sounded when the steel needle was replaced with a chunk of toothpick. You can check out the whole thing in the video below, and you’ll find the G-code generation scripts over on GitHub.

Is all this talk about reproducing music using wiggly lines confusing you? Woah, there, whippersnapper — check out [Jenny]’s primer for the MP3 generation for the background you need.

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No Hole In One: Perseverance Strikes Out On First Mars Core Attempt

There’s a military adage that no plan survives first contact with the enemy. While we haven’t gone to war with Mars, at least not yet, it does seem to be a place where the best-laid scientific plans are tested in the extreme. And the apparent failure of Perseverance to retrieve its first Martian core sample is yet another example of just how hard it is to perform geotechnical operations on another planet.

To be sure, a lot about the first sampling operation went right, an especially notable feat in that the entire process is autonomous. And as we’ve previously detailed, the process is not simple, involving three separate robotic elements that have to coordinate their operations perfectly. Telemetry indicates that the percussive drill on the end of the 2.1 m robotic arm was able to use its hollow coring bit to drill into the rock of Jezero crater, and that the sample tube inside the coring bit was successfully twisted to break off the core sample.

But what was supposed to happen next — jamming of the small core sample inside the sample tube — appears not to have happened. This was assessed by handing the sample tube off to the Sample Handling Arm in the belly of Perseverance, where a small probe is used to see how much material was recovered — none, in this case. NASA/JPL engineers then began a search for the problem. Engineering cameras didn’t reveal the core sample on the Martian surface, meaning the sample handling robots didn’t drop it. The core sample wasn’t in the borehole either, which would have meant the camming mechanism designed to retain the core didn’t work. The borehole, though, looked suspicious — it appears not to be deep enough, as if the core sample crumbled to dust and packed into the bottom of the hole.

If this proves to be the cause of the failure, it will be yet another example of Martian regolith not behaving as expected. For InSight, this discovery was a death knell to a large part of its science program. Thankfully, Perseverance can pick up and move to better rock, which is exactly what it will be doing in September. They still have 42 unused sample tubes to go, so here’s to better luck next time.

[Featured images: NASA/JPL-Caltech]

Geocaching On Mars: How Perseverance Will Seal Martian Samples With A Return To Earth In Mind

With the roughly 20-day wide launch window for the Mars 2020 mission rapidly approaching, the hype train for the next big mission to the Red Planet is really building up steam. And with good reason — the Mars 2020 mission has been in the works for a better part of a decade, and as we reported earlier this year, the rover it’s delivering to the Martian surface, since dubbed Perseverance, will be among the most complex such devices ever fielded.

“Percy” — come on, that nickname’s a natural — is a mobile laboratory, capable of exploring the Martian surface in search of evidence that life ever found a way there, and to do the groundwork needed if we’re ever to go there ourselves. The nuclear-powered rover bristles with scientific instruments, and assuming it survives the “Seven Minutes of Terror” as well as its fraternal twin Curiosity did in 2012, we should start seeing some amazing results come back.

No prior mission to Mars has been better equipped to answer the essential question: “Are we alone?” But no matter how capable Perseverance is, there’s a limit to how much science can be packed into something that costs millions of dollars a kilogram to get to Mars. And so NASA decided to equip Perseverance with the ability to not only collect geological samples, but to package them up and deposit them on the surface of the planet to await a future mission that will pick them up for a return trip to Earth for further study. It’s bold and forward-thinking, and it’s unlike anything that’s ever been tried before. In a lot of ways, Perseverance’s sample handling system is the rover’s raison d’être, and it’s the subject of this deep dive.

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Kitty Litter And Broken Light Bulbs Power This Homebrew Gas Chromatograph

We’re always on the lookout for unexpected budget builds here at Hackaday, and stumbling across a low-cost, DIY version of an instrument that sells for tens of thousands of dollars is always a treat. And so when we saw a tip for a homebrew gas chromatograph in the tips line this morning, we jumped on it. (Video embedded below.)

For those who haven’t had the pleasure, gas chromatography is a chemical analytical method that’s capable of breaking a volatile sample up into its component parts. Like all chromatographic methods, it uses an immobile matrix to differentially retard the flow of a mobile phase containing the sample under study, such that measurement of the transit time through the system can be made and information about the physical properties of the sample inferred.

The gas chromatograph that [Chromatogiraffery] built uses a long stainless steel tube filled with finely ground bentonite clay, commonly known as kitty litter, as the immobile phase. A volatile sample is injected along with an inert carrier gas – helium from a party balloon tank, in this case – and transported along the kitty litter column by gas pressure. The sample interacts with the column as it moves along, with larger species held back while smaller ones speed along. Detection is performed with thermal conductivity cells that use old incandescent pilot lamps that have been cracked open to expose their filaments to the stream of gas; using a Wheatstone bridge and a differential amp, thermal differences between the pure carrier gas and the eluate from the column are read and plotted by an Arduino.

The homebrew GC works surprisingly well, and we can’t wait for [Chromatogiraffery] to put out more details of his build.

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Extraterrestrial Excavation: Digging Holes On Other Worlds

We humans are good at a lot of things, but making holes in the ground has to be among our greatest achievements. We’ve gone from grubbing roots with a stick to feeding billions with immense plows pulled by powerful tractors, and from carving simple roads across the land to drilling tunnels under the English Channel. Everywhere we go, we move dirt and rock out of the way, remodeling the planet to suit our needs.

Other worlds are subject to our propensity for digging holes too, and in the 50-odd years that we’ve been visiting or sending robots as our proxies, we’ve made our marks on quite a few celestial bodies. So far, all our digging has been in the name of science, either to explore the physical and chemical properties of these far-flung worlds in situ, or to actually package up a little bit of the heavens for analysis back home. One day we’ll no doubt be digging for different reasons, but until then, here’s a look at the holes we’ve dug and how we dug them.

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Plant Biology Is A Gateway

Too many college students have been subject to teachers’ aids who think they are too clever to be stuck teaching mere underclassmen. For that reason, [The Thought Emporium] is important because he approaches learning with gusto and is always ready to learn something new himself and teach anyone who wants to learn. When he released a video about staining and observing plant samples, he avoided the biggest pitfalls often seen in college or high school labs. Instead of calling out the steps by rote, he walks us through them with useful camera angles and close-ups. Rather than just pointing at a bottle and saying, “the blue one,” he tells us what is inside and why it is essential. Instead of telling us precisely what we need to see to get a passing grade, he lets our minds wonder about what we might see and shows us examples that make the experiment seem exciting. The video can also be seen below the break.

The process of staining can be found in a biology textbook, and some people learn best by reading, but we haven’t read a manual that makes a rudimentary lab seem like the wardrobe to Narnia, so he gets credit for that. Admittedly, you have to handle a wicked sharp razor, and the chance of failure is never zero. In fact, he will tell you, the opportunities to fail are everywhere. The road to science isn’t freshly paved, it needs pavers.

If a biology lab isn’t in your personal budget, a hackerspace may have one or need one. If you are wondering where you’ve heard [The Thought Emporium]’s voice before, it is because he is fighting lactose intolerance like a hacker.

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Beverly-Crusher, The Greatest Name For An Audio Effect

Image is © aliceazzo [http://aliceazzo.deviantart.com/].
Image © aliceazzo [http://aliceazzo.deviantart.com/].
When it comes to audio effects, you have your delay, reverb, chorus, phasing, and the rest that were derived from strictly analog processes. Compared to the traditional way of doing things, digital audio is relatively new, and there is still untapped potential for new processes and effects. One of those is the bit crusher, an effect that turns 8- or 16-bit audio into mush. [Electronoob] wanted to experiment with bitcrushing, and couldn’t find what he wanted. Undeterred, he built his own.

There are two major effects that are purely in the digital domain. The first is the sample rate reducer. This has a few interesting applications. Because [Shannon] and [Nyquist] say we can only reproduce audio signals less than half of the sample rate; if you run some audio through a sample rate reducer set to 1kHz, it’ll sound like crap, but you’ll also only get bass.

The bitcrusher is a little different. Instead of recording samples of 256 values for 8-bit audio or ~65000 values for 16-bit audio, a one-bit bitcrusher only records one value – on or off. Play it through a speaker at a decent sample rate, and you can still hear it. It sounds like a robotic nightmare, but it’s still there.

[Electronoob] created his bitcrusher purely in software, sending the resulting bitcrushed and much smaller file to an Arduino for playback. Interestingly, he’s also included the ability to downsample audio, giving is project both pure digital effects for the price of one. 1-bit audio is a bit rough on the ears, but 2, 3, and 4-bit audio starts to sound pretty cool, and something that would feel at home in some genres of music.

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