A Beginner’s Guide To X-Ray Crystallography

January 21, 2020 by Dan Maloney 6 Comments

In graduate school, I had a seminar course where one of the sections was about X-ray crystallography. I was excited, because being able to discern the three-dimensional structure of macromolecules just by shining X-rays on them seemed like magic to me. And thanks to a lackluster professor, after the section it remained just as much of a mystery.

If only I’d had [Steve Mould] as a teacher back then. His latest video does an outstanding job explaining X-ray crystallography by scaling up the problem considerably, using the longer wavelength of light and a macroscopic target. He begins with a review of diffraction patterns, those alternating light and dark bands of constructive and destructive interference that result when light shines on two closely spaced slits — the famous “Double-Slit Experiment” that showed light behaves both as a particle and as a wave and provided our first glimpse of quantum mechanics. [Steve] then doubled down on the double-slit, placing another pair of slits in the path of the first. This revealed a grid of spots rather than alternating bands, with the angle between axes dependent on the angle of the slit pairs to each other.

Shining a laser through a light bulb can reveal the structure of DNA 3-29 screenshot

$Photo_51_x-ray_diffraction_image$

Photograph 51, an X-ray crystallogram of the B-form of DNA, by Gosling and Franklin, 1952. Source: Wikipedia

To complete the demonstration, [Steve] then used diffraction to image the helical tungsten filament of an incandescent light bulb. Shining a laser through the helix resulted in a pattern bearing a striking resemblance to what’s probably the most famous X-ray crystallogram ever: [Rosalind Franklin]’s portrait of DNA. It all makes perfect sense, and it’s easy to see how the process works when scaled down both in terms of the target size and the wavelength of light used to probe it.

Hats off to [Steve] for making something that’s ordinarily complex so easily understandable, and for filling in a long-standing gap in my knowledge.

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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]

Oceanography As Open As The Seas

January 17, 2020 by Kristina Panos 12 Comments

With Earth in the throes of climate change and no suitable Planet B lined up just yet, oceanography is as important now as it has ever been. And yet, the instruments relied upon for decades to test ocean conditions are holding steady within the range of expensive to prohibitively expensive. Like any other area of science, lowering the barrier of entry has almost no disadvantages — more players means more data, and that means more insight into the inner workings of the briny deep.

[Oceanography for Everyone] aims to change all that by showing the world just how easy it is to build an oceanographic testing suite that measures conductivity (aka salinity), temperature, and depth using common components. OpenCTD is designed primarily for use on the continental shelf, and has been successfully tested to a depth of 100 meters.

An Adalogger M0 and RTC Featherwing run the show from their waterproof booth in the center of the PVC tube. There’s a 14-bar pressure sensor for depth, a trio of DS18B20s for temperature averaging, and a commercial conductivity probe that gathers salinity data. These sensors are fed through a 3D-printed base plate and ultimately potted in stainless steel epoxy. The other end of the tube is sealed with a mechanical plug that seats and unseats with the whirl of a wingnut.

We particularly like the scratch-built magnetic slide switch that turns OpenCTD on and off without the need to open the cylinder. If you’d like to build one of these for yourself, take a deep dive into [Oceanography for Everyone]’s comprehensive guide — it covers the components, construction, and calibration in remarkable detail. The switch is explained starting on page 50. You can find out more about the work Oceanography for Everyone is doing at their site.

As far as cheap waterproof enclosures go, PVC is a great choice. It works well for underwater photography, too.

The Flexible Permanence Of Copper Tape Circuits

January 15, 2020 by Kristina Panos 23 Comments

Somewhere between shoving components into a breadboard temporarily and committing them to a piece of protoboard or a PCB lies the copper tape method. This flexible Manhattan-style method of circuitry formed the basis for [Bunnie Huang]’s Chibitronics startup, and has since inspired many to stop etching boards and start fetching hoards of copper tape.

[Hales] hit the ground running when he learned about this method, and has made many a copper tape circuit in the last year or so. He offers several nice tips on his site that speak from experience with this method, and he’ll even show you how to easily work an SMD breakout board into the mix.

Generally speaking, [Hales] prefers plywood as the substrate to paper or cardboard for durability. He starts by drawing out the circuit and planning where all the tape traces will go and how wide they need to be. Then he lays out copper traces and pads, rubs the tape against the substrate to make it adhere strongly, and reinforces joints and laps with solder before adding the components. As you can see, copper tape circuits can get pretty complicated if you use Kapton tape as insulation between stacked layers of traces.

Copper and Kapton (polyimide) tape are just two of the many useful tapes you may not be aware of. Stick with us a moment and check out [Nava Whiteford]’s exploration of various adhesive marvels.

DIY Ionizer Clears The Air On A Budget

January 12, 2020 by Dan Maloney 65 Comments

Have you ever had a good, deep breath of the air near a waterfall, or perhaps after a thunderstorm? That unmistakably fresh smell is due to ionized air, specifically negative ions, and many are the claims concerning their health benefits. A minor industry has sprung up to capitalize on the interest in ionized air, and while [Amaldev] wanted to clean up the Mumbai air coming into his home, he didn’t want to pay a lot for a commercial unit. So he built his own air ionizer for only about $10.

When [Amaldev] dropped this in the Hackaday tip line, he indicated that he’d been taking some heat for the design from Instagram followers. We imagine a fair number of the complaints stem from the cluster of sewing needles that bristle from one end of the PCB and are raised to 6,000 volts by a fifteen-stage Cockcroft-Walton multiplier. That’s sure to raise eyebrows, or possible the hair on one’s head if you happen to brush by the emitters. Or perhaps [Amaldev]’s critics are dubious about the benefits of ionized air; indeed, some commenters on the video below seem to think that the smoke in the closed jar was not precipitated by the ion stream as [Amaldev] claims, but rather somehow was settled by heat or some other trickery.

Neither of those bothers us as much as the direct 230-volt mains connection, though. We’d have preferred to see at least an isolation transformer in there, or perhaps a battery-powered flyback circuit to supply the input to that multiplier. Still, the lesson on cascade multipliers was welcome, and we found the smoke-clearing power of ionized air pretty amazing.

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Engineering Overkill Motorizes The Daily Grind

January 9, 2020 by Kristina Panos 26 Comments

You don’t tug on Superman’s cape, and you don’t come between an engineer and his coffee. And really, if all your office has for coffee is a big old BUNN that makes caffeinated trash, you don’t discourage your coworkers from the pursuit of a better brew.

[George] is over at his desk each day treating coffee like the science experiment it is: with a kettle, a Chemex, and a manual coffee grinder. Trouble is, the setup is attracting more and more attention, and [George]’s unpaid side gig as the office barista is starting to wear out his arm. He considered buying an electric grinder just long enough to laugh at the idea, and then went out to the workshop and built this beautifully over-engineered motorized mount for his manual grinder.

The only trouble with motorizing these hand grinders or even driving them with a drill is that many of them have a pentagonal shaft. But that problem was no match for [George] and his file. He soon had his linkage between the 100RPM motor and the grinder shaft and set about building the overly adequate frame.

The whole thing is gorgeous, but we particularly like the gas spring that holds the motor up out of the way while he pours in the beans. [George] probably ought to start a bean fund, if he hasn’t already. That kind of noise followed by the smell of coffee is bound to bring a few more fresh-ground converts into the fold. Grab a fresh cup and grind past the break to see this baby pulverize some beanage.

Not everyone goes for pour over coffee, but there are hacks to be done at all points on the coffee spectrum. Check out [Maya Posch]’s adventures in totally tweaking an espresso machine.

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