One of the reconstructed images, using all 4,096 matrix patterns as input, next to the original object. (Credit: okooptics, Jon Bumstead)
There’s a strange allure to single-pixel cameras due to the simultaneous simplicity and yet fascinating features that they can offer, such as no set resolution limit. That said, the typical implementations that use some kind of scanning (MEMS) mirror or similar approach suffer from various issues even when you’re photographing a perfectly stationary and static scene due to their complex mechanical nature. Yet there’s a way around this, involving a LED matrix and a single photoresistor, as covered by [Jon Bumstead] in an article with accompanying video.

As he points out, this isn’t a new concept, with research papers cited that go back many years. At the core lies the signal processing technique called compressed sensing, which is incidentally also used with computed tomography (CT) and magnetic resonance imaging (MRI) scanners. Compressed sensing enables the reconstruction of a signal from a series of samples, by using existing knowledge of the signal.

In the case of this single-pixel camera, the known information is the illumination, which is a Hadamard matrix pattern displayed on the 64 x 64 pixel LED matrix, ergo 4,096 possible patterns. A total of 4,096 samples are thus recorded, which are subsequently processed with a Matlab script. As pointed out, even 50% of the maximum possible matrices can suffice here, with appropriately chosen patterns.

While not an incredibly fast method, it is fully solid-state, can be adapted to use other wavelengths, and with some tweaking of the used components probably could cut down the sampling time required.

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When [Terence Grover] set out to build a Tamagotchi-inspired simulator, he didn’t just add a few modern tweaks. He ditched the entire concept and rebuilt it from the ground up. Forget cute wide-eyed blobby animals and pixel-poop. This Raspberry Pi-powered project ditches nostalgia in favour of brutal realism: inflation, burnout, capitalism, and the occasional existential crisis. Think Sims meets cyberpunk, rendered charmingly in Python on a low-res RGB LED matrix.

Instead of hunger and poop meters, this dystopian pet juggles Maslow’s hierarchy: hunger, rest, safety, social life, esteem, and money. Players make real-life-inspired decisions like working, socialising, and going into education – each affecting the stats in logical (and often unfair) ways. No free lunch here: food requires money, money requires mind-numbing labour, and labour tanks your rest. You can even die of overwork à la Amazon warehouse. The UI and animation logic are all hand-coded, and there’s a working buzzer, pixel-perfect sprite movement, and even mini-games to simulate job repetition.

It’s equal parts social commentary and pixel art fever dream. While we have covered Tamagotchi recreations some time ago, this one makes you the needy survivor. Want your own dystopia in 64×32? Head over to [Terence Grover]’s Github and fork the full open source code. We’ll be watching. The Tamagotchi certainly is.

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Ovvero... da una parte c'è il gruppo di chi è certo sarà il futuro dell'umanità e che grazie a lei supereremo in un attimo tutti i problemi con cui la nostra specie si è dovuta confrontare negli ultimi 10.000 anni e dall'altra il gruppo di quelli che la considerano il Maligno in formato binario.

Tra i due, il (quasi) nulla.

Ora... calcolate la media e ditemi se mi sono sbagliato.

If the Otis King slide rule in [Chris Staecker’s] latest video looks a bit familiar, you might be getting up there in age, or you might remember seeing us talk about one in our collection. Actually, we have two floating around one of the Hackaday bunkers, and they are quite the conversation piece. You can watch the video below.

The device is often mistaken for a spyglass, but it is really a huge slide rule with the scale wrapped around in a rod-shaped form factor. The video says the scale is the same as a 30-inch scale, but we think it is closer to 66 inches.

Slide rules work using the idea that adding up logarithms is the same as multiplying. For example, for a base 10 logarithm, log(10)=1, log(100)=2, and log(1000)=3. So you can see that 1+2=3. If the scales are printed so that you can easily add and then look up the antilog, you can easily figure out that 10×100=1000.

The black center part acts like a cursor on a conventional slide rule. How does it work? Watch [Chris’] video and you’ll see. We know from experience that one of these in good shape isn’t cheap. Lucky that [Chris] gives us a 3D printed version so you can make your own.

Another way to reduce the scale is to go circular, and you can make one of those, too.

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Google ha accettato di pagare allo Stato del Texas 1,375 miliardi di dollari per risolvere due cause legali sulla privacy. L’azienda è stata accusata di tracciare la posizione degli utenti e di archiviare i loro dati biometrici, tra cui impronte vocali e geometrie facciali, senza il loro consenso.

L’importo del pagamento supera tutte le sanzioni precedentemente imposte da Google in casi simili. In precedenza, nel novembre 2022, la società aveva accettato di pagare 391 milioni di dollari a un gruppo di 40 stati. A gennaio 2023, 29,5 milioni di dollari all’Indiana e a Washington e a settembre, 93 milioni di dollari alla California.

La causa, intentata nel 2022, riguardava la raccolta di dati di geolocalizzazione , attività in modalità di navigazione in incognito e dati biometrici . Secondo i procuratori, Google ha monitorato gli utenti anche quando la funzione Cronologia delle posizioni era disattivata e ha memorizzato i dati biometrici senza preavviso.

“Per anni, Google ha tracciato segretamente i movimenti delle persone, le ricerche private, le impronte vocali e la geometria facciale attraverso i suoi prodotti e servizi”, ha affermato il procuratore generale del Texas Ken Paxton. Ha sottolineato che l’accordo rappresenta una “vittoria storica” ​​per la privacy dei residenti dello Stato.

In risposta alle critiche, Google ha modificato il modo in cui archivia i dati degli utenti: Maps Timeline viene ora archiviato localmente sui dispositivi anziché nel cloud. Sono stati introdotti anche nuovi strumenti che consentono di eliminare automaticamente la cronologia delle posizioni.

Meta, accusata anche di aver raccolto illegalmente i dati biometrici di milioni di utenti, in precedenza aveva pagato la somma equivalente a 1,4 miliardi di dollari al Texas.

Questa iniziativa si inserisce nel contesto della crescente attenzione rivolta alle attività di Google negli Stati Uniti e in Europa. Le autorità di regolamentazione chiedono che il monopolio dell’azienda venga limitato e che venga rivisto il suo approccio al trattamento dei dati personali.

L'articolo Google paga 1,375 miliardi al Texas: la multa sulla privacy più alta di sempre proviene da il blog della sicurezza informatica.

For circuit simulation, we have always been enthralled with the Falstad simulator which is a simple, Spice-like simulator that runs in the browser. [Brandon] has a simulator, too, but it simulates semiconductor devices. With help from [Paul Falstad], that simulator also runs in the browser.

This simulator takes a little thinking and lets you build devices as you might on an IC die. The key is to use the dropdown that initially says “Interact” to select a tool. Then, the drop-down below lets you select what you are drawing, which can be a voltage source, metal, or various materials you find in semiconductor devices, like n-type or a dielectric.

It is a bit tricky, but if you check out the examples first (like this diode), it gets easier. The main page has many examples. You can even build up entire subsystems like a ring oscillator or a DRAM cell.

Designing at this level has its own quirks. For example, in the real world, you think of resistors as something you can use with great precision, and capacitors are often “sloppy.” On an IC substrate, resistors are often the sloppy component. While capacitor values might not be exact, it is very easy to get an extremely precise ratio of two capacitors because the plate size is tightly controlled. This leads to a different mindset than you are used to when designing with discrete components.

Of course, this is just a simulation, so everything can be perfect. If, for some reason, you don’t know about the Falstad simulator, check it out now.

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Sometimes, a little goes a long way. I believe that’s the case with this tiny media control bar from [likeablob] that uses an ESP32-C3 Super Mini.

Image by [likeablob] via Hackaday.IOFrom left to right you’ve got a meta key that allows double functions for all the other keys. The base functions are play/pause, previous track, and next track while the knob handles volume.

And because it uses this Wi-Fi-enabled microcontroller, it can seamlessly integrate with Home Assistant via ESPHome.

What else is under the hood? Four low-profile Cherry MX Browns and a rotary encoder underneath that nicely-printed knob.

If you want to build one of these for yourself, all the files are available on GitHub including the customizable enclosure which [likeablob] designed with OpenSCAD.

Portable Endgame, If It Exists

Perhaps [Palpatine]’s one mistake in creating this 36-key portable endgame is believing in the idea of the endgame in the first place. But I’m not here to judge.

Image by [Palpatine] via redditOh wait, yes I am! I really like this keyboard, and I think it would look right at home on the desk of the centerfold below it, although it’s supposed to be a go-anywhere contraption. Be sure to check out the gallery on this one to see it folded together for transport.

It would seem that [Palpatine] learned some nice tricks while designing this keyboard. Have you heard of 10440 batteries? They’re 3.7 V and usually cheaper than the square Li-Po batteries of the same size.

This bad boy is based on the Seeed Xiao nRF52840, which [Palpatine] believes is worth spending a little bit of extra money on instead of nice!nano clones, while being cheaper than an actual nice!nano would be.

As far as open-sourceness goes, [Palpatine] seems willing to share their design files, although they don’t seem to have been published anywhere at this time.

The Centerfold: White Light Might Bite At Night

Image by [Embarrased-Yak-3766] via redditSo this one isn’t quite as wide as usual, but it’s definitely more white than usual. I suppose that wiiiide monitor makes up for the missing pixels.

What do you think? Crisp and clean, or cold and clinical? I can’t decide. I definitely feel snowbound vibes, and I want to sleep in.

Do you rock a sweet set of peripherals on a screamin’ desk pad? Send me a picture along with your handle and all the gory details, and you could be featured here!

Historical Clackers: the Munson

Image by [Martin Howard] via Antique TypewritersThe delight of the Munson typewriter is in the exposed internal workings, which come to life when the machine is in use. Those octagonal key tops aren’t too shabby, either.

You may have noticed that this machine has no typebars. Instead, it uses a horizontal cylinder about the size of a finger. The cylinder slides from side to side and rotates to find the chosen character. Then a hammer strikes from behind the paper, pushing it against the ribbon and the type cylinder.

Much like the later IBM Selectrics and the daisy wheel machines of the 1970s and ’80s, one could easily change the font by swapping out the all-steel type cylinder. The Munson has two Shift keys, one for upper case and another for figures, so only three rows of keys are needed.

The Munson came out in 1890 and was well-received. It won the highest medal awarded at the World’s Fair Chicago, 1893, but the machines are hard to find these days. Eight years after its introduction, the design of the Munson was acquired by the Chicago Writing Machine Co. and rebranded the Chicago.

Finally, the MingKwai Typewriter Emerges From Obscurity

So you get a Historical Clackers two-fer this week; lucky you! After more than half a century, this fascinating Chinese typewriter turned up while a couple was cleaning out her grandfather’s basement in New York.

Jennifer Felix and her husband Nelson posted photos on a Facebook group trying to ID the machine. A flurry of enthusiastic comments flooded the forum, with many people offering to buy the machine.
Photo by Elisabeth von Boch, courtesy of Stanford Libraries; image via This Is Colossal
As it turns out, it’s a MingKwai — the only one in existence. And it’s now in the hands of Stanford Libraries.

This machine was invented in 1947 by a writer, translator, and linguist named Lin Yutang. The MingKwai, which means “clear and fast”, was the first compact concept Chinese typewriter to have a keyboard that was capable of producing 80,000+ characters.

How is that even possible? Mechanical sort and search. Seriously! Check this out: the 72-key board is made up of strokes and shapes, and the characters are arranged in linear order, like an English dictionary. To use it, you would press one of the 36 top keys and one of the 28 bottom keys simultaneously. This triggered a series of rotations in the internals and would bring eight characters into view in a small window that Lin called the “magic eye”. Finally, you would choose your desired character using the numbered keys in the bottom row.

The only known prototype was built by the Carl E. Krum company. Lin was unable to drum up commercial interest to produce it at scale, so he sold the rights and the prototype to Mergenthaler Linotype Company, where Jennifer Felix’s grandfather worked as a machinist. So it never went into production, and the prototype went home with with Grandpa.

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Got a hot tip that has like, anything to do with keyboards? Help me out by sending in a link or two. Don’t want all the Hackaday scribes to see it? Feel free to email me directly.

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It isn’t too often we post a hack that’s just a pure 3D print with no other components, but for this Giant Molecular Model kit by [3D Printy], we’ll make an exception. After all, even if you print with PLA every day, how often do you get to play with its molecular bonds? (If you want to see that molecule, check out the video after the break.)

There are multiple sizes of bonds to represent bond lengths, and two styles: flexible and firm. Flexible bonds are great for multiple covalent bonds, like carbon-carbon bonds in organic molecules. The bonds clip to caps that screw in to the atoms; alternately a bond-cap can screw the atoms together directly. A plethora of atoms is available, in valence values from one to four. The two-bond atom has 180 and 120-degree variations for greater accuracy. In terms of the chemistry this kit could represent, you’re only limited by your imagination and how long you are willing to spend printing atoms and bonds.

[3D Printy] was kind enough to release the whole lot as CC0 Public Domain, so we might be seeing these at craft fairs, as there’s nothing to keep you from selling the prints. Honestly, we can only hope; from an educational standpoint, this is a much better use of plastic than endless flexy dragons.

If you’d prefer your chemistry toys help you do chemistry, try this fidget spinner centrifuge. Perhaps you’d rather be teaching electronics instead?

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The world’s militaries have always been at the forefront of communications technology. From trumpets and drums to signal flags and semaphores, anything that allows a military commander to relay orders to troops in the field quickly or call for reinforcements was quickly seized upon and optimized. So once radio was invented, it’s little wonder how quickly military commanders capitalized on it for field communications.

Radiotelegraph systems began showing up as early as the First World War, but World War II was the first real radio war, with every belligerent taking full advantage of the latest radio technology. Chief among these developments was the ability of signals in the high-frequency (HF) bands to reflect off the ionosphere and propagate around the world, an important capability when prosecuting a global war.

But not long after, in the less kinetic but equally dangerous Cold War period, military planners began to see the need to move more information around than HF radio could support while still being able to do it over the horizon. What they needed was the higher bandwidth of the higher frequencies, but to somehow bend the signals around the curvature of the Earth. What they came up with was a fascinating application of practical physics: meteor burst communications.

Blame It on Shannon

In practical terms, a radio signal that can carry enough information to be useful for digital communications while still being able to propagate long distances is a bit of a paradox. You can thank Claude Shannon for that, after he developed the idea of channel capacity from the earlier work of Harry Nyquist and Ralph Hartley. The resulting Hartley-Shannon Theorem states that the bit rate of a channel in a noisy environment is directly related to the bandwidth of the channel. In other words, the more data you want to stuff down a channel, the higher the frequency needs to be.

Unfortunately, that runs afoul of the physics of ionospheric propagation. Thanks to the physics of the interaction between radio waves and the charged particles between about 50 km and 600 km above the ground, the maximum frequency that can be reflected back toward the ground is about 30 MHz, which is the upper end of the HF band. Beyond that is the very-high frequency (VHF) band from 30 MHz to 300 MHz, which has enough bandwidth for an effective data channel but to which the ionosphere is essentially transparent.

Luckily, the ionosphere isn’t the only thing capable of redirecting radio waves. Back in the 1920s, Japanese physicist Hantaro Nagaoka observed that the ionospheric propagation of shortwave radio signals would change a bit during periods of high meteoric activity. That discovery largely remained dormant until after World War II, when researchers picked up on Nagoka’s work and looked into the mechanism behind his observations.

Every day, the Earth sweeps up a huge number of meteoroids; estimates range from a million to ten billion. Most of those are very small, on the order of a few nanograms, with a few good-sized chunks in the tens of kilograms range mixed in. But the ones that end up being most interesting for communications purposes are the particles in the milligram range, in part because there are about 100 million such collisions on average every day, but also because they tend to vaporize in the E-level of the ionosphere, between 80 and 120 km above the surface. The air at that altitude is dense enough to turn the incoming cosmic debris into a long, skinny trail of ions, but thin enough that the free electrons take a while to recombine into neutral atoms. It’s a short time — anywhere between 500 milliseconds to a few seconds — but it’s long enough to be useful.
A meteor trail from the annual Perseid shower, which peaks in early August. This is probably a bit larger than the optimum for MBC, but beautiful nonetheless. Source: John Flannery, CC BY-ND 2.0.
The other aspect of meteor trails formed at these altitudes that makes them useful for communications is their relative reflectivity. The E-layer of the ionosphere normally has on the order of 10⁷ electrons per cubic meter, a density that tends to refract radio waves below about 20 MHz. But meteor trails at this altitude can have densities as high as 10¹¹ to 10¹² electrons/m³. This makes the trails highly reflective to radio waves, especially at the higher frequencies of the VHF band.

In addition to the short-lived nature of meteor trails, daily and seasonal variations in the number of meteors complicate their utility for communications. The rotation of the Earth on its axis accounts for the diurnal variation, which tends to peak around dawn local time every day as the planet’s rotation and orbit are going in the same direction and the number of collisions increases. Seasonal variations occur because of the tilt of Earth’s axis relative to the plane of the ecliptic, where most meteoroids are concentrated. More collisions occur when the Earth’s axis is pointed in the direction of travel around the Sun, which is the second half of the year for the northern hemisphere.

Learning to Burst

Building a practical system that leverages these highly reflective but short-lived and variable mirrors in the sky isn’t easy, as shown by several post-war experimental systems. The first of these was attempted by the National Bureau of Standards in 1951. They set up a system between Cedar Rapids, Iowa, and Sterling, Virginia, a path length of about 1250 km. Originally built to study propagation phenomena such as forward scatter and sporadic E, the researchers noticed significant effects on their tests by meteor trails. This made them switch their focus to meteor trails, which caught the attention of the US Air Force. They were in the market for a four-channel continuous teletype link to their base in Thule, Greenland. They got it, but only just barely, thanks to the limited technology of the time. The NBS system also used the Iowa to Virginia system to study higher data rates by pointing highly directional rhombic antennas at each end of the connection at the same small patch of sky. They managed a whopping data rate of 3,200 bits per second with this system, but only for the second or so that a meteor trail happened to appear.

The successes and failures of the NBS system made it clear that a useful system based on meteor trails would need to operate in burst mode, to jam data through the link for as long as it existed and wait for the next one. The NBS tested a burst-mode system in 1958 that used the 50-MHz band and offered a full-duplex link at 2,400 bits per second. The system used magnetic tape loops to buffer data and transmitters at both ends of the link that operated continually to probe for a path. Whenever the receiver at one end detected a sufficiently strong probe signal from the other end, the transmitter would start sending data. The Canadians got in on the MBC action with their JANET system, which had a similar dedicated probing channel and tape buffer. In 1954 they established a full-duplex teletype link between Ottawa and Nova Scotia at 1,300 bits per second with an error rate of only 1.5%

In the late 1950s, Hughes developed a single-channel air-to-ground MBC system. This was a significant development since not only had the equipment gotten small enough to install on an airplane but also because it really refined the burst-mode technology. The ground stations in the Hughes system periodically transmitted a 100-bit interrogation signal to probe for a path to the aircraft. The receiver on the ground listened for an acknowledgement from the plane, which turned the channel around and allowed the airborne transmitter to send a 100-bit data burst. The system managed a respectable 2,400 bps data rate, but suffered greatly from ground-based interference for TV stations and automotive ignition noise.

The SHAPE of Things to Come

Supreme HQ Allied Powers Europe (SHAPE), NATO’s European headquarters in the mid-60s. The COMET meteor-bounce system kept NATO commanders in touch with member-nation HQs via teletype. Source: NATO
The first major MBC system fielded during the Cold War was the Communications by Meteor Trails system, or COMET. It was used by the North Atlantic Treaty Organization (NATO) to link its far-flung outposts in member nations with Supreme Headquarters Allied Powers Europe, or SHAPE, located in Belgium. COMET took cues from the Hughes system, especially its error detection and correction scheme. COMET was a robust and effective MBC system that provided between four and eight teletype circuits depending on daily and seasonal conditions, each handling 60 words per minute.

COMET was in continuous use from the mid-1960s until well after the official end of the Cold War. By that point, secure satellite communications were nowhere near as prohibitively expensive as they had been at the beginning of the Space Age, and MBC systems became less critical to NATO. They weren’t retired, though, and COMET actually still exists, although rebranded as “Compact Over-the-Horizon Mobile Expeditionary Terminal.” These man-portable systems don’t use MBC; rather, they use high-power UHF and microwave transmitters to scatter signals off the troposphere. A small amount of the signal is reflected back to the ground, where high-gain antennas pick up the vanishingly weak signals.

Although not directly related to Cold War communications, it’s worth noting that there was a very successful MBC system fielded in the civilian space in the United States: SNOTEL. We’ve covered this system in some depth already, but briefly, it’s a network of stations in the western part of the USA with the critical job of monitoring the snowpack. A commercial MBC system connected the solar-powered monitoring stations, often in remote and rugged locations, to two different central bases. Taking advantage of diurnal meteor variations, each morning the master station would send a polling signal out to every remote, which would then send back the previous day’s data once a return path was opened. The system could collect data from 180 remote sites in just 20 minutes. It operated successfully from the mid-1970s until just recently, when pervasive cell technology and cheap satellite modems made the system obsolete.

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