2026-01-27 20:00:32
With the powerful off-the-shelf hardware available to us common hardware hobbyist folk, how hard can it be to make a smartphone from scratch? Hence [V Electronics]’s Spirit smartphone project, with the video from a few months ago introducing the project.
As noted on the hardware overview page, everything about the project uses off the shelf parts and modules, except for the Raspberry Pi Compute Module 5 (CM5) carrier board. The LCD is a 5.5″, 1280×720 capacitive one currently, but this can be replaced with a compatible one later on, same as the camera and the CM5 board, with the latter swappable with any other CM5 or drop-in compatible solution.
The star of the show and the thing that puts the ‘phone’ in ‘smartphone’ is the Quectel EG25-GL LTE (4G) and GPS module which is also used in the still-not-very-open PinePhone. Although the design of the carrier board and the 3D printable enclosure are still somewhat in flux, the recent meeting notes show constant progress, raising the possibility that with perhaps some community effort this truly open hardware smartphone will become a reality.
Thanks to [tiel] for the tip.
2026-01-27 17:00:02
When last we saw [xoreaxeax], he had built a lens-less optical microscope that deduced the structure of a sample by recording the diffraction patterns formed by shining a laser beam through it. At the time, he noted that the diffraction pattern was a frequency decomposition of the specimen’s features – in other terms, a Fourier transform. Now, he’s back with an explanation of why this is, deriving equations for the Fourier transform from the first principles of diffraction (German video, but with auto-translated English subtitles. Beware: what should be “Huygens principle” is variously translated as “squirrel principle,” “principle of hearing,” and “principle of the horn”).
The first assumption was that light is a wave that can be adequately represented by a sinusoidal function. For the sake of simplicity (you’ll have to take our word for this), the formula for a sine wave was converted to a complex number in exponential form. According to the Huygens principle, when light emerges from a point in the sample, it spreads out in spherical waves, and the wave at a given point can therefore be calculated simply as a function of distance. The principle of superposition means that whenever two waves pass through the same point, the amplitude at that point is the sum of the two. Extending this summation to all the various light sources emerging from the sample resulted in an infinite integral, which simplified to a particular form of the Fourier transform.
One surprising consequence of the relation is the JPEG representation of a micrograph of some onion cells. JPEG compression calculates the Fourier transform of an image and stores it as a series of sine-wave striped patterns. If one arranges tiles of these striped patterns according to stripe frequency and orientation, then shades each tile according to that pattern’s contribution to the final image, one gets a speckle pattern with a bright point in the center. This closely resembles the diffraction pattern created by shining a laser through those onion cells.
For the original experiment that generated these patterns, check out [xoreaxeax]’s original ptychographical microscope. Going in the opposite direction, researchers have also used physical structures to calculate Fourier transforms.
2026-01-27 14:00:36
If you are interested in historical big computers, you probably think of IBM, with maybe a little thought of Sperry Rand or, if you go smaller, HP, DEC, and companies like Data General. But you may not have heard of Tandem Computers unless you have dealt with systems where downtime was unacceptable. Printing bills or payroll checks can afford some downtime while you reboot or replace a bad board. But if your computer services ATM machines, cash registers, or a factory, that’s another type of operation altogether. That was where Tandem computers made their mark, and [Asianometry] recounts their history in a recent video that you can watch below.
When IBM was king, your best bet for having a computer running nonstop was to have more than one computer. But that’s pricey. Computers might have some redundancy, but it is difficult to avoid single points of failure. For example, if you have two computers with a single network connection and a single disk drive. Then failures in the network connection or the disk drive will take the system down.
The idea started with an HP engineer, but HP wasn’t interested. Tandem was founded on the idea of building a computer that would run continuously. In fact, the name was “the non-stop.” The idea was that smaller computer systems could be combined to equal the performance of a big computer, while any single constituent system failing would still allow the computer to function. It was simply slower. Even the bus that tied the computers together was redundant. Power supplies had batteries so the machines would keep working even through short power failures.
Not only does this guard against failures, but it also allows you to take a single computer down for repair or maintenance without stopping the system. You could also scale performance by simply adding more computers.
Citibank was the first customer, and the ATM industry widely adopted the system. The only issue was that Tandem programs required special handling to leverage the hardware redundancy. Competitors were able to eat market share by providing hardware-only solutions.
The changing computer landscape didn’t help Tandem, either. Tandem was formed at a time when computer hardware was expensive, so using a mostly software solution to a problem made sense. But over time, hardware became both more reliable and less expensive. Software, meanwhile, got more expensive. You can see where this is going.
The company flailed and eventually would try to reinvent itself as a software company. Before that transition could work or fail, Compaq bought the company in 1997. Compaq, of course, would also buy DEC, and then it was all bought up by HP — oddly enough, where the idea for Tandem all started.
There’s a lot of detail in the video, and if you fondly remember Tandem, you’ll enjoy all the photos and details on the company. If you need redundancy down at the component level, you’ll probably need voting.
2026-01-27 11:00:48
Today marks an auspicious anniversary which might have passed us by had it not been for [Diamond Geezer], who reminds us that it’s a hundred years since the first public demonstration of television by John Logie Baird. In a room above what is today a rather famous Italian coffee shop in London’s Soho, he had assembled a complete mechanical TV system that he demonstrated to journalists.
Television is one of those inventions that owes its genesis to more than a single person, so while Baird was by no means the only one inventing in the field, he was the first to demonstrate a working system. With mechanical scanning and just 30 lines, it’s hardly HD or 4K, but it does have the advantage of being within the reach of the constructor.
Perhaps the saddest thing about Baird and his system is that while he was able to attract the interest of the BBC in it, when the time came for dedicated transmissions at a higher resolution, his by then partly mechanical system could not compete and he faded into relative obscurity. Brits instead received EMI’s 405 line system, which persisted until the very start of the 1980s, and eventually the German PAL colour system in the late 1960s.
So head on down to Bar Italia if you can to raise a coffee to his memory, and should you wish to have a go at Baird-style TV for yourself, then you may need to print yourself a disk.
Header image: Matt Brown, CC BY 2.0.
2026-01-27 05:00:21
An analog telephone adapter (ATA), or FXS gateway, is a device that allows traditional analog phones to be connected to a digital voice-over-IP (VoIP) network. In addition to this, you can even create a local phone exchange using just analog phones without connecting to a network as [Playful Technology] demonstrates in a recent video.
The ATA used in the video is the Grandstream HT802, which features one 10/100 Mbps Ethernet port and two RJ11 FXS ports for two POTS phones, allowing for two phones to be directly connected and configured using their own profiles.
By using a multi-FXS port ATA in this manner, you essentially can set up your own mini telephone exchange, with a long run of Cat-3 possible between an individual phone and the ATA. Use of the Ethernet port is necessary just once to configure the ATA, as demonstrated in the video. The IP address of the ATA is amusingly obtained by dialing *** on a connected phone and picking 02 as menu option after which a synthetic voice reads out the number. This IP address gets you into the administration interface.
To configure the ATA as an exchange, the local loopback address is used, along with a dial alias configured in the ‘Dial Plan’ section. This way dialing e.g. 102 gets internally converted to dial the other FXS port. By setting up a similar plan on the other FXS port both phones can call each other, but it’s also possible to auto-dial when you lift the handset off the hook.
The rather hacky configuration ought to make clear that the ATA was not designed to be used in this manner, but if your use case involves this kind of scenario, it’s probably one of the cheaper ways to set up a basic, small phone exchange. There are even ATA models that have more than two ports, opening up more possibilities. Just keep in mind that not every ATA may support this kind of tweaking.
2026-01-27 03:30:54
Before the refrigerator became a normal part of any kitchen, those with enough money to throw around could get an icebox, which used melting ice to cool food and drinks in a second compartment. As refrigerators became available for sale in the 1920s, this created somewhat awkward transition models, like the 1924 Frigidaire B-9 that [David Allen] recently got offered for a restoration. This was part of the restoration of a 1926 house, which foresaw putting this venerable unit back into operation.
As [David] explains, this refrigerator was still in use until about 1970 when it broke down, and repairs proved tricky. Clearly, the fault wasn’t that severe as [David] got it working again after a number of small repairs and a lot of maintenance. The running unit with its basic elements can be seen purring away in the completion video, with the journey to get there covered in a video series starting with the first episode.
What’s fascinating is that during this aforementioned transition period, the vapor compression electric cooling system was an optional extra, meaning that the basic layout is still that of an icebox. Correspondingly, instead of ice in the ice compartment, you find the low-side float evaporator, with the basement section containing the condensing unit, motor, and compressor. The temperature sensor is also a miracle of simplicity, using bellows that respond to the temperature and thus volume of the evaporator coolant, which trigger a switch that turns on the compressor.
Despite a hundred years having passed since this refrigerator was constructed, at its core it works exactly the same as the unit we have in our kitchens today, albeit with higher efficiency, more electronics, and with the sulfur dioxide refrigerant replaced with something less toxic to us humans.
