Be Still, My Animatronic Heart

January 19, 2020 by Dan Maloney 10 Comments

Fair warning for the squeamish: some versions of [Will Cogley]’s animatronic heart are realistic enough that you might not want to watch the video below. That’d be a shame though, because he really put a lot of effort into the build, and the results have a lot to teach about mimicking the movements of living things.

As for why one would need an animatronic heart, we’re not sure. [Will] mentions no specific use case for it, although we can think of a few. With the Day of Compulsory Romance fast approaching, the fabric-wrapped version would make a great gift for the one who stole your heart, while the silicone-enrobed one could be used as a movie prop or an awesome prank. Whatever the reason, [Will]’s build is a case study in incremental development. He started with a design using a single continuous-rotation servo, which powered four 3D-printed paddles from a common crank. The four paddles somewhat mimicked the movements of the four chambers of the heart, but the effect wasn’t quite convincing. The next design used two servos and complex parallelogram linkages to expand each side of the heart in turn. It was closer, but still not quite right.

After carefully watching footage of a beating heart, [Will] decided that his mechanism needed to imitate the rapid systolic contraction and slow diastolic expansion characteristic of a real heart. To achieve this, his final design has three servos plus an Arduino for motion control. Slipped into a detailed silicone jacket, the look is very realistic. Check out the video below if you dare.

We’ve seen plenty of animatronic body parts before, from eyes to hands to entire faces. This might be the first time we’ve seen an animatronic version of an internal organ, though.

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Breathtaking C64C Case Faithfully Recreates Original In Wood

January 18, 2020 by Dan Maloney 23 Comments

Most computer case modders take certain liberties with their builds, to express their creativity and push the state of the art. Some, however, seek to recreate the original in as detailed a way as possible while still being unique. This faithful reproduction of a Commodore 64C in wood is a great example of the latter approach.

[Atilla Meric]’s experience with model airplane building came into play when he decided to leap into this build. Being used to making small, thin pieces of wood even smaller and thinner proved valuable here, as did working from templates and getting complex shapes cut out cleanly. [Atilla] used a miniature table saw to rough cut his stock; the wood species may have been lost in the translation from Turkish but it appears to be some variety of oak. Detail cuts were done with knives, and everything was held together with glue. The painstaking effort that went into the air vents is amazing, and the fact that they exactly match the vents on the original injection-molded case is truly impressive. We also like the subtle detail of the slightly depressed area around the keyboard opening, just like the original, as well as the smooth curve at the front of the case to comfortably support the wrists. The cutouts for connectors and the labels are top-notch too.

We appreciate the craftsmanship that went into this case mod, and the time and effort [Atilla] put into the build are obvious. We’ve seen wooden computer case mods before, but this one really pushes all our buttons.

[via Twitter]

Get Compressed Air From Falling Water With The Trompe

January 17, 2020 by Dan Maloney 24 Comments

If you’re like us, understanding the processes and methods of the early Industrial Revolution involved some hand waving. Take the blast furnace, which relies on a steady supply of compressed air to stoke the fire and supply the oxygen needed to smelt iron from ore. How exactly was air compressed before electricity? We assumed it would have been from a set of bellows powered by a water wheel, and of course that method was used, but it turns out there’s another way to get compressed air from water: the trompe.

As [Grady] from Practical Engineering explains in the short video below, the trompe was a clever device used to create a steady supply of high-pressure compressed air. To demonstrate the process, he breaks out his seemingly inexhaustible supply of clear acrylic piping to build a small trompe. The idea is to use water falling around a series of tubes to create a partial vacuum and entrain air bubbles. The bubbles are pulled down a vertical tube by the turbulence of the water, and then enter a horizontal section where the flow evens out. The bubbles rise to the top of the horizontal tube where they are tapped off by another vertical tube, as the degassed water continues into a second vertical section, the height of which determines the pressure of the stored air. It’s ingenious, requiring no power and no moving parts, and scales up well – [Grady] relates a story about one trompe that provided compressed air commercially for mines in Canada.

Need an electricity-free way to pump water instead of air? Check out this hydraulic ram pump that takes its power from the water it pumps.

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Analyzing CNC Tool Chatter With Audacity

January 16, 2020 by Dan Maloney 32 Comments

When you’re operating a machine that’s powerful enough to tear a solid metal block to shards, it pays to be attentive to details. The angular momentum of the spindle of a modern CNC machine can be trouble if it gets unleashed the wrong way, which is why generations of machinists have developed an ear for the telltale sign of impending doom: chatter.

To help develop that ear, [Zachary Tong] did a spectral analysis of the sounds of his new CNC machine during its “first chip” outing. The benchtop machine is no slouch – an Avid Pro 2436 with a 3 hp S30C tool-changing spindle. But like any benchtop machine, it lacks the sheer mass needed to reduce vibration, and tool chatter can be a problem.

The analysis begins at about the 5:13 mark in the video below, where [Zach] fed the soundtrack of his video into Audacity. Switching from waveform to spectrogram mode, he was able to identify a strong signal at about 5,000 Hz, corresponding to the spindle coming up to speed. The white noise of the mist cooling system was clearly visible too, as were harmonic vibrations up and down the spectrum. Most interesting, though, was the slight dip in frequency during the cut, indicating loading on the spindle. [Zach] then analyzed the data from the cut in the frequency domain and found the expected spindle harmonics, as well the harmonics from the three flutes on the tool. Mixed in among these were spikes indicating chatter – nothing major, but still enough to measure.

Audacity has turned out to be an incredibly useful tool with a broad range of applications. Whether it be finding bats, dumping ROMs, detecting lightning strikes, or cloning remote controls, Audacity is often the hacker’s tool of choice.

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The RFI Hunter: Looking For Noise In All The Wrong Places

January 15, 2020 by Dan Maloney 22 Comments

Next time you get a new device and excitedly unwrap its little poly-wrapped power supply, remember this: for every switch-mode power supply you plug in, an amateur radio operator sheds a tear. A noisy, broadband, harmonic-laden tear.

The degree to which this fact disturbs you very much depends upon which side of the mic you’re on, but radio-frequency interference, or RFI, is something we should all at least be aware of. [Josh (KI6NAZ)] is keenly aware of RFI in his ham shack, but rather than curse the ever-rising noise floor he’s come up with some helpful tips for hunting down and eliminating it – or at least reducing its impact.

Attacking the problem begins with locating the sources of RFI, for which [Josh] used the classic “one-circuit-at-a-time” approach – kill every breaker in the panel and monitor the noise floor while flipping each breaker back on. This should at least give you a rough idea of where the offending devices are in your house. From there, [Josh] used a small shortwave receiver to locate problem areas, like the refrigerator, the clothes dryer, and his shack PC. The family flat-screen TV proved to be quite noisy too. Remediation techniques include wrapping every power cord and cable around toroids or clamping ferrite cores around them, both on the offending devices and in the shack. He even went so far as to add a line filter to the dryer to clamp down on its unwanted interference.

Judging by his waterfall displays, [Josh]’s efforts paid off, bringing his noise floor down from S5 to S1 or so. It’s too bad he had to take matters into his own hands – it’s not like the FCC and other spectrum watchdogs don’t know there’s a problem, after all.

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Camcorder Viewfinder Converted To Diminutive Vector Display

January 14, 2020 by Dan Maloney 26 Comments

We generally cast a skeptical eye at projects that claim some kind of superlative. If you go on about the “World’s Smallest” widget, the chances are pretty good that someone will point to a yet smaller version of the same thing. But in the case of what’s touted as “The world’s smallest vector monitor”, we’re willing to take that chance.

If you’ve seen any of [Arcade Jason]’s projects before, you’ll no doubt have noticed his abiding affection for vector displays. We’re OK with that; after all, many of the best machines from the Golden Age of arcade games such as Asteroids and Tempest were based on vector graphics. None so small as the current work, though, based as it is on the CRT from an old camcorder’s viewfinder. The tube appears to be about 3/4″ (19 mm) in diameter, and while it still had some of its original circuitry, the deflection coils had to be removed. In their place, [Jason] used a ferrite toroid with two windings, one for vertical and one for horizontal. Those were driven directly by a two-channel push-pull audio amplifier to make patterns on the screen. Skip to 15:30 in the video below to see the display playing [Jerobeam Fenderson]’s “Oscilloscope Music”.

As much as we’d love to see a tiny game of Battlezone played on the diminutive display, there’s only so much it can do. Maybe an analog version of this adorable digital oscilloscope would be possible?

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Habitable Exoplanets Hack Chat

January 13, 2020 by Dan Maloney 1 Comment

Join us on Wednesday, January 15 at noon Pacific for the Habitable Exoplanets Hack Chat with Alberto Caballero!

Many of the major scientific achievements of the last 100 years or so have boiled down to problems of picking out a signal from the noise. Think about analyzing the human genome, for instance: we each have something like two meters of DNA coiled up inside each cell in our body, and yet teasing out the information in a single gene had to wait until we developed sufficiently sophisticated methods like PCR and CRISPR.

Similarly, albeit on the other end of the scale, the search for planets beyond our solar system wasn’t practical until methods and instruments that could measure the infinitesimal affect a planet’s orbit on its star were developed. Once that door was unlocked, reports of exoplanets came flooding in, and Earth went from being a unique place in the galaxy to just one of many, many places life could possibly have gotten a foothold. And now, the barrier for entry to the club of planet hunters has dropped low enough that amateur astronomers are getting in on the action.

Alberto Caballero is one such stargazer, and he has turned his passion for astronomy into an organized project that is taking a good, hard look at some of our nearest stellar neighbors in the hope of finding exoplanets in the habitable zone. The Habitable Exoplanet Hunting Project is training the instruments in 33 observatories around the globe on ten stars within 100 light-years, hoping to detect the faint signal that indicates an orbiting planet. They hope to add to the list of places worthy of exploration, both from Earth via optical and radio telescopes, and perhaps, someday, in person.
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