World’s First Precision Lathe: Indispensable When Constructing The Antikythera Mechanism

January 7, 2024 by Maya Posch 27 Comments

The precision lathe with the hooks, the bowstring, and vise visible as material is being processed. (Credit: Clickspring)

We commonly tend to associate lathes with the Industrial Revolution, when metalworking shifted largely from blacksmiths to machinists, but the use of lathes is much older than that. As [Chris] over at the Clickspring YouTube channel demonstrates in a recent video, small precision lathes were exceedingly common in the Ancient World. Not only is there ample historical evidence of them being used as far back as 1300 BCE in Ancient Egypt, but they’re also the most optimal way to get perfectly round pins and other, more intricate shapes that would be an absolute nightmare to create with just some metal files and chisels.

In the video, [Chris] uses two metal hooks, bent in a ninety-degree angle and clamped down in a vise, tapering towards each other into points. A bow string around a round piece of wood is used to bootstrap a more permanent retention element and bushing for the bow string as it is drawn over the wood to rotate it. Subsequent material that has to be worked on in the lathe is then clamped between the two points. This way, using basic materials that have been around for thousands of years and some muscle power, it’s possible to create a small lathe that can be used to create perfectly symmetrical shapes, such as those used in the construction of the Antikythera Mechanism, which [Chris] has been rebuilding for the past years, using only period-correct tools. He’s learned a lot about the mechanism in the process.

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Using Sound Waves As A Fire Extinguisher

January 7, 2024 by Maya Posch 15 Comments

In order for a fire to sustain itself, it needs three things: fuel, heat, and oxygen, with the disruption of just one of those causing the fire to extinguish. Water, sand, and carbon dioxide-based fire extinguishers are commonly used, but you’re probably familiar with blowing out a candle using your breath. Counter-intuitively, we also blow on a fire (or use bellows) to make it burn better, so what is happening here? Starting with a novelty app for smartphones that can be used to blow out small flames like candles, [The Action Lab] digs into the topic in a recent video.

Using an air vortex cannon strapped to a bass reflex port to wiggle a flame to death. (Credit: The Action Lab)

Using a fairly beefy speaker to blast a 70 Hz tone at a big alcohol flame was not enough to extinguish it, but using the bass reflex port on the back was more effective, yet still not nearly enough. Using an air vortex cannon to focus the sound waves from the bass reflex port, it ‘wiggles’ the flame out in a matter of seconds, as illustrated with a thermal camera. Compared to the much stronger airflow from the box fan that was also used in one attempt, the difference with the sound waves is that they oscillate, constantly fluctuating the air pressure.

This churns the air and thus the flame around, diffusing the suspended fuel, cooling the air, and alternatingly pushing oxygenated air and carbon dioxide-heavy combustion fumes into the flame. This differs from the constant flow from the box fan, which only pushes oxygen-rich air into the flame, thus keeping it intact and burning brightly. Perhaps the main question that remains here is just how practical this approach is for extinguishing flames. Some commentators suggested using this approach in low- and zero-gravity situations, as found in space stations, where regular fire extinguishers based around smothering a flame aren’t as practical.

(Thanks to [Hyperific] for the tip)

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802.11ah Wi-Fi HaLOW: The 1 Kilometer WiFi Standard

January 7, 2024 by Maya Posch 31 Comments

The 802.11ah WiFi (HaLow) standard is fairly new, having only been introduced in 2017. It’s supposed to fall somewhere between standard WiFi used in domiciles and offices and the longer range but low-bitrate LoRaWAN, ZigBee, and others, with bandwidth measured in megabits per second. In a recent video, [Ben Jeffery] looks at the 802.11ah chipsets available today and some products integrating these.

The primary vendors selling these chipsets are TaiXin Semiconductor (TXW8301), Morse Micro (MM6108), and Newracom (NRC7394), with a range of manufacturers selling modules integrating these. Among the products using these, [Ben] found an Ethernet range extender kit (pictured) that takes 12V input as power, along with Ethernet. Running some distance tests in a quarry showed that 300 meters was no problem getting a strong signal, though adding some trees between the two transceivers did attenuate the signal somewhat.

Another interesting product [Ben] tested is what is essentially an 802.11ah-based WiFi extender, using an 802.11ah link between the server node – with an Ethernet socket – and a client that features a standard 2.4 GHz 802.11n that most WiFi-enabled devices can connect to. Using this, he was able to provide a solid ~10 Mbps link to a cabin near the main house (~10 meters) through two outside walls. What makes 802.11ah so interesting is that it is directly compatible with standard Ethernet and WiFi protocols and uses the 900 MHz spectrum, for which a wide range of alternative antennae exist that can conceivably extend the range even more.

(Thanks to [Keith Olson] for the tip)

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Video And Audio Playback On Low-End MS-DOS Machines

January 5, 2024 by Maya Posch 13 Comments

For most people the phrases ‘MS-DOS’ and ‘video playback’ probably aren’t commonly associated, yet it was quite normal as those of us who were watching full-motion video with games like Command & Conquer can attest to. These audiovisual experiences did however require somewhat more capable hardware than something like an original, 4.77 MHz IBM PC. More recently, however, the removal of these limitations has been turned into a challenge that has been gleefully accepted by hackers, including [Scali] whose recent tinkering with getting not only real-time video but also audio working on these old beasts has been documented on their blog.

Unlike existing early video formats like FLIC from the 1990s, the XDC format developed over the past years enables real-time, 60 FPS video and audio playback on an 8088 IBM PC that has a SoundBlaster 2 and CGA card installed. As [Scali] notes, the SB2 card is convenient, because it enables DMA transports for the audio data, which saves a lot of precious CPU cycles. Unlike the original SB card, it also fixes some teething issues, but an SB2 is hardly ‘low-end’ for an early 1980s PC, so it has to go.

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Teardown Of Two Russian Missile Sensors

January 5, 2024 by Maya Posch 23 Comments

Recently [Michel] received two packages from Ukraine containing some salvaged Russian electronics that once belonged to (presumably) a 9K38 Igla, Vympel R-27 or similar infrared homing missile, as well as a Fiber Optic Gyroscope (FOG) from an unknown missile, though possibly from the Tornado family of MRLSes. The latter uses the Sagnac effect to detect the phase shift between two laser beams being injected into the same fiber when the fiber, and thus the device, are rotating. The advantage of such a gyroscope is that it is effectively solid-state, requiring only some optical components, amplifier stage and as shown here an Altera Cyclone II FPGA to integrate the results.

The 16-channel linear infrared array sensor is more basic, with a matching amplification channel for each optical receiver element, which are fed into a multiplexer IC in a rather remarkable looking ceramic-gold packaged DIP format, with what looks like a 2004 date code (‘0424’). Although both are rather damaged, [Michel] figures that he might be able to restore the FOG to working condition, assuming no crucial and irreplaceable parts are missing. As useful as FOGs are in missiles, they also have countless uses outside of military applications.

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Niklaus Wirth with Personal Computer Lilith that he developed in the 1970ies. (Photo: ETH Zurich)

Remembering Niklaus Wirth: Father Of Pascal And Inspiration To Many

January 5, 2024 by Maya Posch 33 Comments

Although perhaps not as much of a household name as other pioneers of last century’s rapid evolution of computer hardware and the software running on them, Niklaus Wirth’s contributions puts him right along with other giants. Being a very familiar face both in his native Switzerland at the ETH Zurich university – as well as at Stanford and other locations around the world where computer history was written – Niklaus not only gave us Pascal and Modula-2, but also inspired countless other languages as well as their developers.

Sadly, Niklaus Wirth passed away on January 1st, 2024, at the age of 89. Until his death, he continued to work on the Oberon programming language, as well as its associated operating system: Oberon System and the multi-process, SMP-capable A2 (Bluebottle) operating system that runs natively on x86, X86_64 and ARM hardware. Leaving behind a legacy that stretches from the 1960s to today, it’s hard to think of any aspect of modern computing that wasn’t in some way influenced or directly improved by Niklaus.

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How Good Is The Cheapest Generator On Amazon?

January 4, 2024 by Maya Posch 79 Comments

Although an internal combustion engine-based generator isn’t exactly one of the most complicated contraptions, any time that you combine something that produces power with electrical devices, you generally like to know how safe it is. Even more so when it’s a $139 generator you got off Amazon, like the PowerSmart 1200 Watt (1000 continuous) that the [Silver Cymbal] took a gander at recently. They used an expensive professional power analyzer to look at more than just the basic waveform of the 120 VAC output to figure out what kind of devices you’d feel comfortable connecting to it.

Waveform analysis of the cheapest generator when under load. Looks better than with no load attached.

On the unit there is a single AC output, which a heater got attached to serve as a load during testing, but before that, the properties out of the output voltage were analyzed without any load. This showed a highly erratic waveform, as the generator clearly was unable to synchronize and produced a voltage within a wide range, immediately disqualifying it for connecting to sensitive electronics. Things got less dire once the load was hooked up and turned up to use up a big chunk of the available continuous power.

Although being far from a perfect sine wave, the output now looked much better, with all properties including the total harmonic distortion (THD) being just a hair over 20% and hitting just over 60 Hz on the frequency.

Definitely not a great result, but as a cheap unit to keep around for powering things like heaters and power tools that aren’t too fussy about how clean the power is, one could do a lot worse.

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