Colorful parachutes at different levels of expansion

Holy Parachute Out Of Kirigami

If you have a fear of heights and find yourself falling out of an airplane, you probably don’t want to look up to find your parachute full of holes. However, if the designer took inspiration from kirigami in the same way researchers have, you may be in better shape than you would think. This is because properly designed kirigami can function as a simple and effective parachute.

Kirigami, for those unfamiliar, is a cousin of origami where, instead of folding, you cut slits into paper. In this case, the paper effectively folds itself after being dropped, which allows the structure to create drag in ways similar to traditional parachute designs. Importantly, however, the stereotypical designs of parachutes have some more severe drawbacks than they appear. Some major issues include more obvious things, such as having to fold and unpack before and after dropping. What may be less obvious are the large eddies that traditional parachutes create or their ease at being disturbed by the surrounding wind.

The kirigami chutes fix these issues while being easier to manufacture and apply. While these are not likely to be quite as effective for human skydiving, more durable applications may benefit. Quoted applications, including drone delivery or disaster relief, worry more about accuracy and scalability rather than the fragile bones of its passenger.

Clever and simple designs are always fun to try to apply to your own projects, so if you want to have your own hand, make sure to check out the paper itself here. For those more interested in clever drone design to take inspiration from, look no further than this maple seed-inspired drone.

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Can A Coin Cell Make 27 Volts?

We have all no doubt at some point released the magic smoke from a piece of electronics, it’s part of what we do. But sometimes it’s a piece of electronics we’re not quite ready to let go, and something has to be fixed. [Chris Greening] had a board just like that, a 27 volt generator from an LCD panel, and he crafted a new circuit for it.

The original circuit, which we think he may have drawn incorrectly, uses a small boost converter IC with the expected inductor and diode. His replacement is the tried and tested joule thief, but with a much higher base resistor than its normal application in simply maintaining a battery voltage. It sucks 10 mA from the battery and is regulated with a Zener diode, but there’s still further room for improvement. Adding an extra transistor and using the Zener as a feedback component causes the oscillator to shut off as the voltage increases, something which in this application is fine.

It’s interesting to see a joule thief pushed into a higher voltage application like this, but we sense perhaps it could be made more efficient by seeking out an equivalent to the boost converter chip. Or even a flyback converter.

A High Resolution ADC From Scratch

It’s a well-known conundrum that while most computers these days are digital in nature, almost nothing in nature is. Most things we encounter in the real world, whether it’s temperature, time, sound, pressure, or any other measurable phenomenon comes to us in analog form. To convert these signals to something understandable by a digital converter we need an analog-to-digital converter or ADC, and [Igor] has built a unique one from scratch called a delta sigma converter.

What separates delta sigma converters apart is their high sampling rate combined with a clever way of averaging the measurements to get a very precise final value. In [Igor]’s version this average is provided by an op-amp that integrates the input signal and a feedback signal, allowing for an extremely precise digital value to be outputted at the end of the conversion process. [Igor] has built this one from scratch as well, and is using it to interface a magnetic rotary encoder to control digital audio playback.

Although he has this set up with specific hardware, he has enough detail in his video (including timing diagrams and explanations of all of the theory behind these circuits) for anyone else to build one of these for other means, and it should be easily adaptable for plenty of uses. There are plenty of different ADC topologies too, and we saw many different ones a few years ago during our op-amp challenge.

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A Treasure Trove Of Random Vintage Tech Resources

Finding, collecting, and restoring vintage tech is the rewarding pastime of many a Hackaday reader. Working with old-school gear can be tough, though, when documentation or supporting resources are hard to find. If you’re in need of an old manual or a little scrap of software, you might find the Vintage Technology Digital Archive (VTDA) a useful destination.

The VTDA is a simple website. There is no search function, or fancy graphical way to browse the resources on offer. Instead, it’s merely a collection of files in a well-ordered directory tree. Click through /pics/DiskSleeves/VTDA/ and you’ll find a collection of high-resolution scans of various old diskettes and their packaging. /docs/computing/Centronics/ will give you all kinds of useful documentation, from press releases to datasheets for printers long forgotten. You can even find Heathkit schematics and old Windows bootdisk images if you dive into the depths.

While it doesn’t have everything, by any means, the VTDA has lots of interesting little bits and pieces that you might not find anywhere else. It’s a great counterpart to other archival efforts out on the web, particularly if you’re a member of the retrocomputing massive.

Thanks to [Itay] for the tip!

On 3D Scanners And Giving Kinects A New Purpose In Life

The concept of a 3D scanner can seem rather simple in theory: simply point a camera at the physical object you wish to scan in, rotate around the object to capture all angles and stitch it together into a 3D model along with textures created from the same photos. This photogrammetry application is definitely viable, but also limited in the sense that you’re relying on inferring three-dimensional parameters from a set of 2D images and rely on suitable lighting.

To get more detailed depth information from a scene you’d need to perform direct measurements, which can be done physically or through e.g. time-of-flight (ToF) measurements. Since contact-free ways of measurements tend to be often preferred, ToF makes a lot of sense, but comes with the disadvantage of measuring of only a single spot at a time. When the target is actively moving, you can fall back on photogrammetry or use an approach called structured-light (SL) scanning.

SL is what consumer electronics like the Microsoft Kinect popularized, using the combination of a visible and near-infrared (NIR) camera to record a pattern projected onto the subject, which is similar to how e.g. face-based login systems like Apple’s Face ID work. Considering how often Kinects have been used for generic purpose 3D scanners, this raises many questions regarding today’s crop of consumer 3D scanners, such as whether they’re all just basically Kinect-clones.

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How A Failed Video Format Spawned A New Kind Of Microscope

The video cassette tape was really the first successful home video format; discs just couldn’t compete back in the early days. That’s not to say nobody tried, however, with RCA’s VideoDisc a valiant effort that ultimately fell flat on its face. However, the forgotten format did have one benefit, in that it led to the development of an entirely new kind of microscope, as explained by IEEE Spectrum.

The full story is well worth the read; the short version is that it all comes down to capacitance. RCA’s VideoDisc format was unique in that it didn’t use reflective surfaces or magnetic states to represent data. Instead, the data was effectively stored as capacitance changes. As a conductive stylus rode through an undulating groove in a carbon-impregnated PVC disc, the capacitance between the stylus and the disc changed. This capacitance was effectively placed into a resonant circuit, where it would alter the frequency over time, delivering an FM signal that could be decoded into video and audio by the VideoDisc player.

The VideoDisc had a capacitance sensor that could detect such fine changes in capacitance, that it led to the development of the Scanning Capacitance Microscope (SCM). The same techniques used to read and inspect VideoDiscs for quality control could be put to good use in the field of semiconductors. The sensors were able to be used to detect tiny changes in capacitance from dopants in a semiconductor sample, and the SCM soon became an important tool in the industry.

It’s perhaps a more inspiring discovery than when cheeky troublemakers figured out you could use BluRay diodes to pop balloons. Still fun, though. An advertisement for the RCA VideoDisc is your video after the break.

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Play Capacitor Cupid With The Matchmaker

Occasionally a design requires capacitors that are much closer to being identical in value to one another than the usual tolerance ranges afford. Precision matching of components from parts on hand might sound like a needle-in-a-haystack problem, but not with [Stephen Woodward]’s Capacitor Matchmaker design.

The larger the output voltage, the greater the mismatch between capacitors A and B.

The Matchmaker is a small circuit intended to be attached to a DVM, with the output voltage indicating whether two capacitors (A and B) are precisely matched in value. If they are not equal, the voltage output indicates the degree of the mismatch as well as which is the larger of the two.

The core of the design is complementary excitation of the two capacitors (the CD4013B dual flip-flop achieves this) which results in a measurable signal if the two capacitors are different; nominally 50 mV per % of mismatch. Output polarity indicates which of the capacitors is the larger one. In the case of the two capacitors being equal, the charges cancel out.

Can’t precision-matched capacitors be purchased? Absolutely, but doing so is not always an option. As [Stephen] points out, selection of such components is limited and they come at an added cost. If one’s design requires extra-tight tolerances, requires capacitor values or types not easily available as precision pairs, or one’s budget simply doesn’t allow for the added cost, then the DIY approach makes a lot more sense.

If you’re going to go down this road, [Stephen] shares an extra time-saving tip: use insulated gloves to handle the capacitors being tested. Heating up a capacitor before testing it — even just from one’s fingers — can have a measurable effect.

[Stephen]’s got a knack for insightful electronic applications. Check out his PWMPot, a simple DIY circuit that can be an awfully good stand-in for a digital potentiometer.