3D Printer Emission Monitor Quantifies The Stench

While we don’t yet know the long-term effects of hanging out around 3D printers, it doesn’t take a in-depth study to figure out that their emissions aren’t healthy. What smells toxic usually is toxic. Still, it’s oh-so-fun to linger and watch prints grow into existence, even when we have hundreds or thousands of hours of printing under our belts.

Most of us would agree that ABS stinks worse than PLA, and that’s probably because it releases formaldehyde when melted. PLA could be viewed as slightly less harmful because it has a lower melting point, and more volatile organic compounds (VOCs) are released at higher temperatures. Though we should probably always open a window when printing, human nature is a strong force. We need something to save us from our stubbornness, and [Gary Peng] has the answer: a smart 3D printer emission monitor.

The monitor continually checks the air quality and collects data about VOC emissions. As the VOCs become elevated during printing, the user is notified with visual, audio, and phone notifications. Green means you’re good, yellow means open a window, red means GTFO. There’s a brief demo after the break that also shows the phone interface.

The heart of this monitor is a CCS811 gas sensor, which provides VOC data to a Particle Photon. [Gary] built a simple Blynk interface to handle the alerts and graph historical VOC readings. He’s got the code and STLs available, so let this be the last time you watch something print in blissful semi-ignorance.

Concerned about air quality in general? Here’s a standalone portable monitor designed to quantify the soul-crushing stuffiness of meetings.

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Play To The Beat Of This Robotic Drummer In A Box

No drummer? No problem! With a little ingenuity, you can stuff the essentials of a drum kit into a box, and automate your rhythm section.

Mind you, [Franco Molina]’s “DrumCube” doesn’t quite have the flash of a human drummer, but it does keep a steady beat and has a charm of its own. The drum machine is mostly mechanical, reminding us somewhat of the Wintergatan Marble Machine which is as captivating to watch as it is to hear. The DrumCube has a snare drum played by two servo-controlled sticks, a kick drum using foam waggled back and forth between two piezo transducers hooked to a low-pass filter, and a reverse-biased transistor white noise generator used for the hi-hat. Sadly, the large gear appears to be just for show. An Arduino runs everything and makes sure the mechanical drum hits are synced to the electronic cymbals, which was no mean feat.

The video below shows it in action accompanying [Franco] on his guitar, and it looks as good as it sounds.¬†Prefer a more compact, all-electronic drum kit? Here’s one that fits in your pocket.

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Piezoelectric Crystals Explained

Summer in the Northern hemisphere means outdoor cooking. Matches are old school, and you are more likely to use a piezoelectric lighter to start your grill. [Steve Mould] has one, but he didn’t understand the physics behind why it works, so he decided to do the research and share it in a video.

The first two minutes is a recap of things you already know. But after that [Steve] gets into the crystal lattice structure of quartz. Using some computer animations and some peanut butter lids he shows you exactly why compressing the crystal generates electricity.

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Piezoelectric Antennas For Very, Very Low Frequencies

If you want to talk about antennas, the amateur radio community has you covered, with one glaring exception. Very low frequency and Extremely Low Frequency radio isn’t practiced very much, ultimately because it’s impractical and you simply can’t transmit much information when your carrier frequency is measured in tens of Hertz. There is more information on Extremely Low Frequency radio in Michael Crichton’s Sphere than there is in the normal parts of the Internet. Now there might be an easier way to play with VLF radiation, thanks to developers at the National Accelerator Laboratory. They’ve developed a piezoelectric transmitter for very long wavelengths.

Instead of pushing pixies through an antenna, this antenna uses a rod-shaped crystal of lithium niobate, a piezoelectric material. An AC voltage is applied to the rod makes it vibrate, and this triggers an oscillating electric current flow that’s emitted as VLF radiation. The key is that it’s these soundwaves bouncing around that define the resonant frequency, and the speed of sound in lithium niobate is a lot slower than the speed of light, but they’re translated into electric signals because of its piezoelectricity. For contrast, if this were a wire quarter-wave antenna it would be tens of kilometers long.

The application for this sort of antenna is ideally for where regular radio doesn’t work. Radio doesn’t work underwater, but nuclear subs trail an antenna out of the back to receive messages using Extremely Low Frequency radio. A walkie talkie doesn’t work in a mine, and this could potentially be used there. There is a patent for this piezoelectric antenna, so if anyone knows of a source of lithium niobate, put a link in the comments.

We’ve seen this trick before to make small antennas even smaller, but this is the first time we’ve seen it used in the VLF band, where it’s arguably even more impressive.

Hacking Nature’s Musicians

We just wrapped up the Musical Instrument Challenge in the Hackaday Prize, and for most projects that meant replicating sounds made by humans, or otherwise making musicians for humans. There’s more to music than just what can be made in a DAW, though; the world is surrounded by a soundscape, and you only need to take a walk in the country to hear it.

For her Hackaday Prize entry, [Kelly] is hacking nature’s musicians. She’s replicating the sounds of the rural countryside in transistors and PCBs. It’s an astonishing work of analog electronics, and it sounds awesome, too.

The most impressive board [Kelly] has been working on is the Mother Nature Board, a sort of natural electronic chorus of different animal circuits. It’s all completely random, based on a Really, Really Random Number Generator, and uses a collection of transistors and 555 timers to create pulses sent to a piezo. This circuit is very much sensitive to noise, and while building it [Kelly] found that not all of her 2N3904 transistors were the same; some of them worked for the noise generator, some didn’t. This is a tricky circuit to design, but the results are delightful.

So, can analog electronics sound like a forest full of crickets? Surprisingly, yes. This demonstration¬†shows what’s possible with a few breadboards full of transistors, caps, resistors, and LEDs. It’s an electronic sculpture of the sounds inspired by the nocturnal soundscape of rural Virginia. You’ve got crickets, cicadas, katydids, frogs, birds, and all the other non-human musicians in the world. Beautiful.

Superdeep Borehole Samples Create Non-boring Music

In the 1970s, the Soviet Union decided to dig a hole for science. Not just any hole, the Kola Superdeep Borehole reached a depth of over 12 kilometers, the deepest at the time and the second deepest today by just a few meters. Since this was one of the few holes dug this deep that wasn’t being drilled for oil, the project was eventually abandoned. [Dmitry] was able to find some core samples from the project though, and he headed up to the ruins of the scientific site with his latest project which produces musical sounds from the core samples.

The musical instrument uses punched tape, found at the borehole site, as a sort of “seed” for generating the sounds. Around the outside of the device are five miniature drilling rigs, each holding a piece of a core sample from the hole. The instrument uses the punched tape in order to control the drilling rigs, and the sound that is created is processed by the instrument and amplified, which creates some interesting and rather spooky sounds. The whole thing is controlled by an Arduino Mega.

Not only does the project make interesting sounds from a historically and scientifically significant research station and its findings, but the project has a unique and clean design that really fits its environment at the abandoned facility. The other interesting thing about this project is that, if you want to make the trek, anyone can go explore the building and see the hole for themselves. If you’re wondering about the tools that could be used to make a hole like this, take a look at this boring project.

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Turning Everything Into A Tap Controller

Our entire life is staring at glowing rectangles, and all our surroundings are hard, flat surfaces. [Ben] had the idea to turn those flat surfaces into a generic tap interface controller, and his project for the Hackaday Prize might just do that.

Some of the prior art that went into this project includes Ping Pong Plus Plus, an augmented-reality-ish implementation of ping pong that puts projected light wherever a ping pong ball hits the table. The game does this by mounting piezos to the bottom of a table and just a slight bit of math to determine where on the table the ball hit. There’s also MicLoc, a door lock that responds to knocking.

With this prior art, it’s all about microcontrollers and peripherals, and for that, [Ben] turned to the STM32F303RE, which sports four very fast ADCs and op-amps. There’s a lot of DMA usage on there, and the code is using a ton of signal processing. The important bit here is finding the difference between whatever the tabletop equivalent to an earthquake’s P-waves and S-waves are — [Ben] only wants the first bit of a waveform that travels through the table longitudinally, not the much louder vibrations of the entire table.

If [Ben] manages to put this together, an entire wall could be a light switch or a dimmer. You could add a secret knock to your door, and your desk could control your computer. It’s a promising idea, and the engineering that’s going into this project is just fantastic.