The End Of Landlines?

February 8, 2024 by 94 Comments

Imagine if, somehow, telephones of all kinds had not been invented. Then, this morning, someone entered a big corporation board room and said, “We’d like to string copper wire to every home and business in the country. We’ll get easements and put the wires on poles mostly. But some of them will go underground where we will dig tunnels. Oh, and we will do it in other countries, too, and connect them with giant undersea cables!” We imagine that executive would be looking for a job by lunchtime. Yet, we built that exact system and with far less tech than we have today. But cell phones have replaced the need for copper wire to go everywhere, and now AT&T is petitioning California to let them off the hook — no pun intended — for servicing landlines.

The use of cell phones has dramatically decreased the demand for the POTS or plain old telephone service. Even if you have wired service now, it is more likely fiber optic or, at least, an IP-based network connection that can handle VOIP.

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Revisiting A Z80 Game From 1990

February 8, 2024 by 16 Comments

Back in the days of 8-bit computers, like no doubt many readers of similar age, we wrote little games. First in BASIC, then augmented with little machine code speed-ups. We didn’t come close to [Óscar Toledo Gutiérrez] though, who’s reverse engineering a 2K all-machine-code game he wrote back in 1990. As a tale of software archaeology it’s fascinating.

The game itself is an avoid-the-monsters platformer with plenty of ladders for the little sprite-based protagonist to run down. The computer was a Mexican homebrew educational machine with a TMS9118 display chip and an AY-3-8910 synthesizer, so the result had both color and music. His run through the code breaks it down neatly into individual sections, so it’s possible to see what’s going on without an in-depth knowledge of machine code.

He readily admits it bears all the hallmarks of an 11-year-old’s knowledge at the time, and that it has some parts less elegant, but nevertheless it’s something of an achievement at any age. It was out of date gameplay-wise in 1990 but in 1982 it could probably have been bought on a tape by eager kids. Here in 2024 he’s got it for download should you have a Colecovision or an MSX. There’s a gameplay video below the break, take a look.

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How Airplanes Mostly Stopped Flying Into Terrain And Other Safety Improvements

February 8, 2024 by 13 Comments

We have all heard the statistics on how safe air travel is, with more people dying and getting injured on their way to and from the airport than while traveling by airplane. Things weren’t always this way, of course. Throughout the early days of commercial air travel and well into the 1980s there were many crashes that served as harsh lessons on basic air safety. The most tragic ones are probably those with a human cause, whether it was due to improper maintenance or pilot error, as we generally assume that we have a human element in the chain of events explicitly to prevent tragedies like these.

Among the worst pilot errors we find the phenomenon of controlled flight into terrain (CFIT), which usually sees the pilot losing track of his bearings due to a variety of reasons before a usually high-speed and fatal crash. When it comes to keeping airplanes off the ground until they’re at their destination, here ground proximity warning systems (GPWS) and successors have added a layer of safety, along with stall warnings and other automatic warning signals provided by the avionics.

With the recent passing of C. Donald Bateman – who has been credited with designing the GPWS – it seems like a good time to appreciate the technology that makes flying into the relatively safe experience that it is today.

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The Revolver: A 3D-Printed… Screwdriver!

February 8, 2024 by 19 Comments

You know those “What my friends think I do” vs “What I actually do” memes? Well there should be one for 3D printing that highlights what you think you’ll do before buying your first printer vs what you actually wind up printing once you get it!

However, thanks to [Revolver3DPrints] you can fulfill your dream of printing a useful tool that looks like a commercial product, the Revolver two-speed screwdriver. The screwdriver isn’t motorized, but it has an interesting midsection that can be rotated to spin the bit, and you can select between a speed and torque mode.

The Revolver isn’t a solution looking for a problem. The designer noted a few issues with normal screwdrivers. They are hard to get into tight spaces, which was the biggest issue. The Revolver is compact, and since you turn its midsection, you don’t have to have clearance for your hand on the top. The gear ratios allow you to apply more torque without needing a long handle.

As you may have guessed, the internal arrangement is a planetary gear drive. You might consider if you want to print this using resin or FDM printing. You also need some screwdriver bits, some glue, and a few magnets to complete the project. If you prefer to make a motorized screwdriver, we’ve seen that done, too.

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Custom Multi-Segment E-Ink Displays From Design To Driving

February 8, 2024 by 21 Comments

With multi-segment displays, what you see available online is pretty much what you get. LEDs, LCDs, VFDs; if you want to keep your BOM at a reasonable price, you’ve pretty much got to settle for whatever some designer thinks looks good. And if the manufacturer’s aesthetic doesn’t match yours, it’s tough luck for you.

Maybe not though. [upir] has a thing for custom displays, leading him to explore custom-made e-ink displays. The displays are made by a company called Ynvisible, and while they’re not exactly giving away the unique-looking flexible displays, they seem pretty reasonably priced. Since the displays are made with a screen printing process, most of the video below concerns getting [upir]’s preferred design into files suitable for printing. He uses Adobe Illustrator for that job, turning multi-segment design ideas by YouTuber [Posy] into chunky displays. There are some design restrictions, of course, chief of which is spacing between segments. [upir] shows off some Illustrator-fu that helps automate that process, as well as a host of general vector graphics design tips and tricks.

After sending off the design files to Ynvisible and getting the flexible displays back, [upir] walks us through the details of driving them. It’s not as simple as you’d think, at least in the Arduino world; the segments need +1.5 volts with reference to the common connection to turn on, and -1.5 volts to turn off. His clever solution is to use an Arduino Uno R4 and take advantage of the onboard DAC. To turn on a segment, he connects a segment to a GPIO pin set high while sending 3.5 volts out of the DAC output into the display’s common connection. The difference between the two pins is 1.5 volts, turning the segment on. To turn it off, he drops the DAC output to 1.5 volts and drives the common GPIO pin low. Pretty clever, and no extra circuitry is required.

This isn’t the first time we’ve seen [upir] trying to jazz things up in the display department. He’s played with masking LED matrix displays with SMD stencils before, and figured out how to send custom fonts to 16×2 displays too.

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A schematic representation of the different ionospheric sub-layers and how they evolve daily from day to night periods. (Credit: Carlos Molina)

Will Large Satellite Constellations Affect Earth’s Magnetic Field?

February 7, 2024 by 48 Comments

Imagine taking a significant amount of metals and other materials out of the Earth’s crust and scattering it into the atmosphere from space. This is effectively what we have been doing ever since the beginning of the Space Age, with an increasing number of rocket stages, satellites and related objects ending their existence as they burn up in the Earth’s atmosphere. Yet rather than vanish into nothing, the debris of this destruction remains partially in the atmosphere, where it forms pockets of material. As this material is often conductive, it will likely affect the Earth’s magnetic field, as argued by [Sierra Solter-Hunt] in a pre-publication article.

A summary by [Dr. Tony Phillips] references a 2023 NASA research article by [Daniel M. Murphy] et al. which describes the discovery that about 10% of the aerosol particles in the stratosphere are aluminium and other metals whose origin can be traced back to the ‘burn-up’ of the aforementioned space objects. This is a factor which can increase the Debye length of the ionosphere. What the exact effects of this may be is still largely unknown, but fact remains that we are launching massively more objects into space than even a decade ago, with the number of LEO objects consequently increasing.

Although the speculation by [Sierra] can be called ‘alarmist’, the research question of what’ll happen if over the coming years we’ll have daily Starlink and other satellites disintegrating in the atmosphere is a valid one. As this looks like it will coat the stratosphere and ionosphere in particular with metal aerosols at levels never seen before, it might be worth it to do the research up-front, rather than wait until we see something odd happening.

Metal Crystal Stops Electrons

February 7, 2024 by 14 Comments

Researchers at Rice University have found an alloy of copper, vanadium, and sulfur that forms crystals that, due to quantum effects, can trap electrons. This can produce flat bands, which have been observed in 2D crystals previously. The team’s results are the first case of a 3D crystal with that property.

The flat band term refers to the electron energy bands. Normally, the electrons change energy levels based on momentum. But in a flat band, this doesn’t occur. This implies that the electrons are nearly stationary, which leads to unique optical, electronic, and magnetic properties. In addition, flat-band materials often exhibit unusual behavior, such as exotic quantum states, ferromagnetism, or even superconductivity.

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