High Voltage Gives Metal Balls A Mind Of Their Own

May 25, 2021 by 19 Comments

Have you ever seen something that’s so fascinating you’re sure there has to be some kind of practical application for it, but you just can’t figure out what? That’s how we feel when watching tiny ball bearings assemble themselves into alien-like structures under the influence of high voltage in the latest Plasma Channel video from [Jay Bowles].

Now to be clear, [Jay] isn’t trying to take credit for the idea. He explains that researchers at Stanford University first documented the phenomenon back in 2015, and that his goal was to recreate their initial results as a baseline and go from there. The process is pretty simple: put small metal ball bearings into a tray of oil, apply high voltage, and watch them self-assemble into “wires” that branch out in search of the ground terminal like a plant’s roots looking for water. With the encouragement of his 500,000 volt Van de Graaff generator, the ball bearings leaped into action and created structures just like in the Stanford study.

With the basic pieces now in place, [Jay] starts to push the envelope. He experiments with various oils to see how their viscosity impacts the ball’s ability to assemble, finding that olive oil seems to be the ideal candidate (at least of those he’s tried so far). He also switches up the size and shape of the tray, to try and find how far the balls can realistically stretch out on their own.

In the end we’re no closer to finding a practical application for this wild effect than the good folks at Stanford were back in 2015, but at least we got to watch the little fellows do their thing in glorious 4K and with the exceptional production value we’ve come to expect from Plasma Channel. That said, [Jay] does hint at his ongoing efforts to turn the structures into works of art by “freezing” them with clear resin, so keep your eyes out for that.

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Ask Hackaday: How Is The Chip Shortage Affecting You?

May 24, 2021 by 133 Comments

Some friends of mine are designing a new board around the STM32F103 microcontroller, the commodity ARM chip that you’ll find in numerous projects and on plenty of development boards. When the time came to order the parts for the prototype, they were surprised to find that the usual stockholders don’t have any of these chips in stock, and more surprisingly, even the Chinese pin-compatible clones couldn’t be found. The astute among you may by now have guessed that the culprit behind such a commodity part’s curious lack of availability lies in the global semiconductor shortage.

A perfect storm of political unintended consequences, climate-related crises throttling Taiwanese chip foundries and shutting down those in the USA, and faulty pandemic recovery planning, has left the chipmakers unable to keep up with the demand from industries on the rebound from their COVID-induced slump. Particularly mentioned in this context is the automotive industry, which has seen plants closing for lack of chips and even models ditching digital dashboards for their analogue predecessors.

Chips on order everywhere on the Mouser website.
Chips on order everywhere on the Mouser website.

The fall-out from all this drama in the world’s car factories has filtered down through all levels that depend upon semiconductors; as the carmakers bag every scrap of chip fab capacity that they can, so in turn have other chip customers scrambled to keep their own supply lines in place. A quick scan for microcontrollers through distributors like Mouser or Digi-Key finds pages and pages of lines on back-order or out of stock, with those lines still available being largely either for niche applications, unusual package options, or from extremely outdated product lines. The chances of scoring your chosen chip seem remote and most designers would probably baulk at trying to redesign around an ancient 8-bit part from the 1990s, so what’s to be done?

Such things typically involve commercially sensitive information so we understand not all readers will be able to respond, but we’d like to ask the question: how has the semiconductor shortage affected you? We’ve heard tales of unusual choices being made to ship a product with any microcontroller that works, of hugely overpowered chips replacing commodity devices, and even of specialist systems-on-chip being drafted in to fill the gap. In a few years maybe we’ll feature a teardown whose author wonders why a Bluetooth SoC is present without using the radio functions and with a 50R resistor replacing the antenna, and we’ll recognise it as a desperate measure from an engineer caught up in 2021’s chip shortage.

So tell us your tales from the coalface in the comments below. Are you that desperate engineer scouring the distributors’ stock lists for any microcontroller you can find, or has your chosen device remained in production? Whatever your experience we’d like to know what the real state of the semiconductor market is, so over to you!

With A Big Enough Laser, The World Is Your Sensor

May 21, 2021 by 31 Comments

It’s difficult to tell with our dull human senses, but everything around us is vibrating. Sure it takes more energy to get big objects like bridges and houses humming compared to a telephone pole or mailbox, but make no mistake, they’ve all got a little buzz going on. With their new automated laser, the team behind VibroSight++ believes they can exploit this fact to make city-scale sensing far cheaper and easier than ever before.

The key to the system is a turret mounted Class 3B infrared laser and photodetector that can systematically scan for and identity reflective surfaces within visual range. Now you might think that such a setup wouldn’t get much of a signal from the urban landscape, but as it so happens, the average city block is packed with retroreflectors. From street signs to road studs and license plates, the team estimates dense urban areas have approximately 7,000 reflectors per square kilometer. On top of those existing data points, additional reflectors could easily be added to particularly interesting devices that city planners might want to monitor.

Once VibroSight++ has identified its targets, the next step is to bounce the laser off of them and detect the minute perturbations in the returned signal caused by vibrations in the reflector. In the video below you can see how this basic concept could be put to practical use in the field, from counting how many cars pass over a certain stretch of road to seeing how popular a specific mailbox is. There’s a whole world of information out there just waiting to be collected, all without having to install anything more exotic than the occasional piece of reflective tape.

If this technology seems oddly familiar, it’s probably because we covered the team’s earlier work that focused (no pun intended) on using reflected laser beams for home automation in 2018. Back then they were aiming a much smaller laser at blenders and refrigerators instead of license plates and street signs, but the concept is otherwise the same. While we’ll admit the technology does give off a distinctive Orwellian vibe, it’s hard not to be intrigued by the “Big Data” possibilities afforded by the team’s upgraded hardware and software.

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A “Disgusting” 1980s Computer Restored

May 17, 2021 by 42 Comments

It takes a special eye to see a junkyard car and envision it as your latest hotrod. The guys at RMC found what they termed a “disgusting” Acorn Electron and decided to restore it to its former glory. The Electron was a budget version of the BBC micro with a 6502 running at 2 MHz when executing code from ROM and 1 MHz when it hit the RAM. Apparently, at least some of the bus was operating at 4 bits instead of 8. Go figure.

The 1982 machine was meant to head off the Sinclair ZX and was set to sell for about £200. However, the machine didn’t catch on like the Sinclair and undersold it by around 20 times with a paltry quarter of a million units.

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Thought Control Via Handwriting

May 16, 2021 by 12 Comments

Computers haven’t done much for the quality of our already poor handwriting. However, a man paralyzed by an accident can now feed input into a computer by simply thinking about handwriting, thanks to work by Stanford University researchers. Compared to more cumbersome systems based on eye motion or breath, the handwriting technique enables entry at up to 90 characters a minute.

Currently, the feat requires a lab’s worth of equipment, but it could be made practical for everyday use with some additional work and — hopefully — less invasive sensors. In particular, the sensor used two microelectrode arrays in the precentral gyrus portion of the brain. When the subject thinks about writing, recognizable patterns appear in the collected data. The rest is just math and classification using a neural network.

If you want to try your hand at processing this kind of data and don’t have a set of electrodes to implant, you can download nearly eleven hours of data already recorded. The code is out there, too. What we’d really like to see is some easier way to grab the data to start with. That could be a real game-changer.

More traditional input methods using your mouth have been around for a long time. We’ve also looked at work that involves moving your head.

Vintage HP-25 Calculator Gets Wireless Charging

May 15, 2021 by 9 Comments

[Jan Rychter] really likes his multiple HP-25C calculators, but the original battery pack design is crude and outdated. No problem — he whips up a replacement using Fusion 360 to design an enclosure, prints a few on his SLS 3D printer, and packs them with LiPo batteries and Qi/WPC wireless charging circuits.

In his blog post, he explains the goals and various design decisions and compromises that he made along the way. We like [Jan]’s frank honesty as he remarks on something we have all been guilty of at one time or another:

In the end, I went with design decisions which might not be optimal, but in this case (with low power requirements) provide acceptable performance. In other words, I winged it.

One problem which proved difficult to solve was how to provide a low battery indicator. Since low voltage on a LiPo is different from the original HP-25’s NiCad cells, it wasn’t straightforward, especially since [Jan] challenged himself to build this without using a microcontroller. He discovered that the HP-25’s internal low battery circuit was triggered by a voltage of 2.1 volts or lower.

In a really clever hack, [Jan] came up with the idea of using an MCU reset supervisor chip with a low voltage threshold of 3.0 volts, which corresponds with the low voltage threshold of the LiPo battery he is using. The reset signal from the supervisor chip then drives one of the pins of the TPS62740 programmable buck converter, changing its output from 2.5 volts to 2.1 volts.

This project is interesting on several levels — extending the life of a useful but end-of-life calculator, improving the original battery design and introducing new charging techniques not available in the early 1970s, and it is something that a hobbyist can afford to do in a home electronics lab. We do wonder, could such a modification could turn an HP-25 into an HP-25C?

We’ve written about battery pack replacement project before, including one for the Sony Discman and another for an electric drill. Let us know if you have any battery pack replacement success (or failure) stories in the comments below.

Calibrating A VNA The Proper Way

May 8, 2021 by 16 Comments

Those of us who have bought cheap TinyVNA devices for our RF experimentation will be used to the calibration procedure involving short-circuit, 50 Ω, and open terminations, followed by a direct connection between ports. We do this with a kit of parts supplied with the device, and it makes it ready for our measurements. What we may not fully appreciate at the level of owning such a basic instrument though, is that the calibration process for much higher-quality instruments requires parts made to a much higher specification than the cheap ones from our TinyVNA. Building a set of these high-quality parts is a path that [James Wilson] has taken, and in doing so he presents a fascinating discussion of VNA calibration and the construction of standard RF transmission line components.

We particularly like the way that after constructing his short, load and open circuit terminations using high-quality SMA sockets, he put a custom brass fitting 3D printed by Shapeways on the end of each to make them easier to handle while preserving their RF integrity. If we’d bought a set of terminations looking like these ones as commercial products we would be happy with their quality, but the real test lay in their performance. Thanks to a friend he was able to get them tested on instruments with much heftier price tags, and found them to be not far short of the simulation and certainly acceptable within his 3 GHz range.

Curious about VNAs at the affordable end of the spectrum? We took a look at the TinyVNA, which while it is something of a toy is still good enough for lower frequency measurements.