There is perhaps no more important time to have a business card than when you’re in college, especially near the end when you’re applying for internships and such. And it’s vital that you stand out from the crowd somehow. To that end, Electrical & Computer Engineer [Ryan Chan] designed a tidy card that plays tic-tac-toe.

Instead of X and O, the players are indicated by blue and red LEDs. Rather than having a button at every position, there is one big control button that gets pressed repeatedly until your LED is in the desired position, and then you press and hold to set it and switch control to the other player. In addition to two-player mode, the recipient of your card can also play alone against the ATMega.

The brains of this operation is an ATMega328P-AU with the Arduino UNO bootloader for ease of programming. Schematic and code are available if you want to make your own, but we suggest implementing some type of changes to make it your own. Speaking of, [Ryan] has several next steps in mind, including charlieplexing the LEDs, using either USB-C or a coin cell for power, upgrading the AI, and replacing the control button with a capacitive pad or two. Be sure to check it out in action in the two videos after the break.

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Displays are crucial to modern life; they are literally everywhere. But modern flat-panel LCDs and cheap 7-segment LED displays are, well, a bit boring. When we hackers want to display the progress of time, we want something more interesting, hence the plethora of projects using Nixie tubes and various incantations of edge-lit segmented units. Here is [upir] with their take on the simple edge-lit acrylic 7-segment design, with a great video explanation of all the steps involved.
Engraving the acrylic sheets by hand using 3D printed stencils
The idea behind this concept is not new. Older displays of this type used tiny tungsten filament bulbs and complex light paths to direct light to the front of the display. The modern version, however, uses edge-lit panels with a grid of small LEDs beneath each segment, which are concealed within a casing. This design relies on the principle of total internal reflection, created by the contrast in refractive indices of acrylic and air. Light entering the panel from below at an angle greater than 42 degrees from normal is entirely reflected inside the panel. Fortunately, tiny LEDs have a wide dispersion angle, so if they are positioned close enough to the edge, they can guide sufficient light into the panel. Once this setup is in place, the surface can be etched or engraved using a CNC machine or a laser cutter. A rough surface texture is vital for this process, as it disrupts some of the light paths, scattering and directing some of it sideways to the viewer. Finally, to create your display, design enough parallel-stacked sheets for each segment of the display—seven in this case, but you could add more, such as an eighth for a decimal point.

How you arrange your lighting is up to you, but [upir] uses an off-the-shelf ESP32-S3 addressable LED array. This design has a few shortcomings, but it is a great start—if a little overkill for a single digit! Using some straightforward Arduino code, one display row is set to white to guide light into a single-segment sheet. To form a complete digital, you illuminate the appropriate combination of sheets. To engrave the sheets, [upir] wanted to use a laser cutter but was put off by the cost. A CNC 3018 was considered, but the choice was bewildering, so they just went with a hand-engraving pick, using a couple of 3D printed stencils as a guide. A sheet holder and light masking arrangement were created in Fusion 360, which was extended into a box to enclose the LED array, which could then be 3D printed.

If you fancy an edge-lit clock (you know you do) check out this one. If wearables are more your thing, there’s also this one. Finally, etched acrylic isn’t anywhere near as good as glass, so if you’ve got a vinyl cutter to hand, this simple method is an option.

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[Luizão] wanted to create some hardware to honour the memory of the technology used to put man on the moon and chose the literal core of the project, that of the hardware used to store the software that provided the guidance. We’re talking about the magnetic core rope memory used in the Colossus and Luminary guidance computers. [Luizão] didn’t go totally all out and make a direct copy but instead produced a scaled-down but supersized demo board with just eight cores, each with twelve addressable lines, producing a memory with 96 bits.

The components chosen are all big honking through-hole parts, reminiscent of those available at the time, nicely laid out in an educational context. You could easily show someone how to re-code the memory with only a screwdriver to hand; no microscope is required for this memory. The board was designed in EasyEDA, and is about as simple as possible. Being an AC system, this operates in a continuous wave fashion rather than a pulsed operation mode, as a practical memory would. A clock input drives a large buffer transistor, which pushes current through one of the address wires via a 12-way rotary switch. The cores then act as transformers. If the address wire passes through the core, the signal is passed to the secondary coil, which feeds a simple rectifying amplifier and lights the corresponding LED. Eight such circuits operate in parallel, one per bit. Extending this would be easy.

Obviously, we’ve covered the Apollo program a fair bit. Here’s a fun tale about recovering the guidance software from the real hardware. Like always, the various space programs create new technologies that we mere mortals get to use, such as an auto-dialling telephone.

(video in Brazilian Portuguese)

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[Ken Shirriff] likes to take chips apart and this time his target is an NFC chip used in Montreal transit system tickets. As you might expect, the tickets are tiny, cheap, and don’t have any batteries. So how does it work?

The chip itself is tiny at 570 µm × 485 µm. [Ken] compares it to a grain of salt. The ticket has a thin plastic core with a comparatively giant antenna onboard.

Working with such a tiny chip presented additional challenges. A few drops of boiling sulphuric acid freed the die. Then applications of phosphoric acid, Armour etch — nasty stuff, but better than hydroflouric acid — and hydrochloric acid took care of the rest.

With everything exposed, it was time to analyze the different parts. As you’d expect, the NFC tag draws power from the antenna and sends data from a EEPROM. There was some analog circuitry and also some digital gates used to control the output. But there isn’t room for much.

How are these so cheap? You can order an 8-inch wafer with 100,587 chips onboard. The price? Around $9,000 per wafer, so about nine cents per chip. Actually, you may be more because the wafer actually has 103,682 dice but a file included tells you which ones are bad. If you want to bargain shop, a 12-inch wafer is $19,000 but gives you 215,712 dice. What a steal!

Can’t get enough NFC? We understand. There are times you just want to make your own.

It is funny how sometimes things you think are bad turn out to be good in retrospect. Like many of us, when I was a kid, I was fascinated by science of all kinds. As I got older, I focused a bit more, but that would come later. Living in a small town, there weren’t many recent science and technology books, so you tended to read through the same ones over and over. One day, my library got a copy of the relatively recent book “The Amateur Scientist,” which was a collection of [C. L. Stong’s] Scientific American columns of the same name. [Stong] was an electrical engineer with wide interests, and those columns were amazing. The book only had a snapshot of projects, but they were awesome. The magazine, of course, had even more projects, most of which were outside my budget and even more of them outside my skill set at the time.

If you clicked on the links, you probably went down a very deep rabbit hole, so… welcome back. The book was published in 1960, but the projects were mostly from the 1950s. The 57 projects ranged from building a telescope — the original topic of the column before [Stong] took it over — to using a bathtub to study aerodynamics of model airplanes.

X-Rays

[Harry’s] first radiograph. Not bad!However, there were two projects that fascinated me and — lucky for me — I never got even close to completing. One was for building an X-ray machine. An amateur named [Harry Simmons] had described his setup complaining that in 23 years he’d never met anyone else who had X-rays as a hobby. Oddly, in those days, it wasn’t a problem that the magazine published his home address.

You needed a few items. An Oudin coil, sort of like a Tesla coil in an autotransformer configuration, generated the necessary high voltage. In fact, it was the Ouidn coil that started the whole thing. [Harry] was using it to power a UV light to test minerals for flourescence. Out of idle curiosity, he replaced the UV bulb with an 01 radio tube. These old tubes had a magnesium coating — a getter — that absorbs stray gas left inside the tube.

The tube glowed in [Harry’s] hand and it reminded him of how an old gas-filled X-ray tube looked. He grabbed some film and was able to image screws embedded in a block of wood.
With 01 tubes hard to find, why not blow your own X-ray tubes?
However, 01 tubes were hard to get even then. So [Harry], being what we would now call a hacker, took the obvious step of having a local glass blower create custom tubes to his specifications.

Given that I lived where the library barely had any books published after 1959, it is no surprise that I had no access to 01 tubes or glass blowers. It wasn’t clear, either, if he was evacuating the tubs or if the glass blower was doing it for him, but the tube was down to 0.0001 millimeters of mercury.

Why did this interest me as a kid? I don’t know. For that matter, why does it interest me now? I’d build one today if I had the time. We have seen more than one homemade X-ray tube projects, so it is doable. But today I am probably able to safely operate high voltages, high vaccums, and shield myself from the X-rays. Probably. Then again, maybe I still shouldn’t build this. But at age 10, I definitely would have done something bad to myself or my parent’s house, if not both.

Then It Gets Worse

The other project I just couldn’t stop reading about was a “homemade atom smasher” developed by [F. B. Lee]. I don’t know about “atom smasher,” but it was a linear particle accelerators, so I guess that’s an accurate description.
The business part of the “atom smasher” (does not show all the vacuum equipment).
I doubt I have the chops to pull this off today, much less back then. Old refigerator compressors were run backwards to pull a rough vaccuum. A homemade mercury diffusion pump got you the rest of the way there. I would work with some of this stuff later in life with scanning electron microscopes and similar instruments, but I was buying them, not cobbling them together from light bulbs, refigerators, and home-made blown glass!

You needed a good way to measure low pressure, too, so you needed to build a McLeod gauge full of mercury. The accelerator itself is three foot long, borosilicate glass tube, two inches in diameter. At the top is a metal globe with a peephole in it to allow you to see a neon bulb to judge the current in the electron beam. At the bottom is a filament.

The globe at the top matches one on top of a Van de Graf generator that creates about 500,000 volts at a relatively low current. The particle accelerator is decidedly linear but, of course, all the cool particle accelerators these days form a loop.

[Andres Seltzman] built something similar, although not quite the same, some years back and you can watch it work in the video below:

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What could go wrong? High vacuum, mercury, high voltage, an electron beam and plenty of unintentional X-rays. [Lee] mentions the danger of “water hammers” in the mercury tubes. In addition, [Stong] apparently felt nervous enough to get a second opinion from [James Bly] who worked for a company called High Voltage Engineering. He said, in part:

…we are somewhat concerned over the hazards involved. We agree wholeheartedly with his comments concerning the hazards of glass breakage and the use of mercury. We feel strongly, however, that there is inadequate discussion of the potential hazards due to X-rays and electrons. Even though the experimenter restricts himself to targets of low atomic number, there will inevitably be some generation of high-energy X-rays when using electrons of 200 to .300 kilovolt energy. If currents as high as 20 microamperes are achieved, we are sure that the resultant hazard is far from negligible. In addition, there will be substantial quantities of scattered electrons, some of which will inevitably pass through the observation peephole.

I Survived

Clearly, I didn’t build either of these, because I’m still here today. I did manage to make an arc furnace from a long-forgotten book. Curtain rods held carbon rods from some D-cells. The rods were in a flower pot packed with sand. An old power cord hooked to the curtain rods, although one conductor went through a jar of salt water, making a resistor so you didn’t blow the fuses.

Somehow, I survived without dying from fumes, blinding myself, or burning myself, but my parent’s house had a burn mark on the floor for many years after that experiement.

If you want to build an arc furnace, we’d start with a more modern concept. If you want a safer old book to read, try the one by [Edmund Berkeley], the developer of the Geniac.

Avete mai provato a chiedere ad un surfista di qualsiasi parte del mondo che cosa rappresenta il surf per lei o per lui? Sono certa al 100% che tutti vi daranno la stessa risposta: Libertà. Perché nulla al mondo dona quella sensazione come scivolare su un’onda, come remare verso il largo, circondati dal rosso del cielo e dal caldo del sole che tramonta. Pensateci bene, che cos’è la libertà? Per davvero intendo. @Feddit Un'istanza italiana Lemmy

iyezine.com/gaza-surf-chronicl…

GAZA SURF CHRONICLES E1

GAZA SURF CHRONICLES E1 - Quante volte abbiamo sentito questi termini dando per scontato una certa distanza tra noi e i soggetti in questione. Come se ci fosse non solo una distanza fisica, ma anche e soprattutto morale.

^{Valentina Sala (In Your Eyes ezine)}

Non si poteva resistere al richiamo dei supereroi monobanda, e allora InYourEyes ha risposto "presente" a un appuntamento davvero imperdibile, @Musica Agorà

iyezine.com/bob-log-iii-one-ma…

BOB LOG III / ONE MAN BUZZ - LIVE REPORT (13-6-2024)

BOB LOG III / ONE MAN BUZZ - LIVE REPORT (13-6-2024) - Non si poteva resistere al richiamo dei supereroi monobanda, e allora InYourEyes ha risposto "presente" a un appuntamento davvero imperdibile, incentrato sulle "one man band", che si è tenuto a P…

^{Reverend Shit-Man (In Your Eyes ezine)}

Dopo la rivoluzione del 25 aprile 1974, il 2 maggio, con questo gesto, José P. Maia (1943-2013) ha dimostrato le potenzialità dell'occupazione collettiva e ha dato voce a una lotta che continua. Tanta gente senza casa, tante case senza gente.

Murale fotografato a Lisbona, agosto 2014.

Ilaria Salis è stata eletta al Parlamento Europeo dopo che il giorno precedente l'apertura dei seggi le gazzette l'hanno ritratta come una occupante abusiva di abitazioni. Uno dei peggiori stigmi che il gazzettaio "occidentalista" riesca a gettare.
Dopo qualche giorno dall'elezione Ilaria Salis ha fatto circolare questo scritto. Come nostro uso lo si riporta perché urta chi merita quantomeno di essere urtato. Dobbiamo anche lodare la concretezza della scrivente e il suo non ricorrere al linguaggio inclusivo.

Sì, lo confesso!
Sono stata una militante del movimento di lotta per la casa che negli anni ha dato battaglia sul tema del diritto all'abitare, a Milano e in tutta Italia.
Se qualcuno pensava di fare chissà quale scoop scavando nel mio passato, è solo perché è sideralmente lontano dalla realtà sociale di tale movimento, che si compone di decine di migliaia di abitanti delle case popolari e attivisti, i quali, per aver affermato il semplice principio di avere un tetto sulla testa, sono incappati in qualche denuncia.
Sarebbe auspicabile che l'informazione, piuttosto che gettare fango sul mio conto, si dedicasse al contesto di grave povertà e precarietà abitativa nel quale si ritrovano ampie fasce di popolazione.
Le pratiche collettive dell'occupazione di case sfitte, il blocco degli sfratti, la resistenza agli sgomberi, gli sportelli di ascolto e la lotta per la sanatoria rappresentano un'alternativa reale e immediata all’isolamento sociale e alla guerra tra poveri, strumentalizzate tanto dalle forze politiche razziste quanto dal racket.
Dare una risposta concreta al bisogno dell'abitare significa non solo trovare qui e ora una soluzione, benché precaria e provvisoria, ad una questione lasciata irrisolta dalla politica istituzionale, ma anche indicare una prospettiva politica di trasformazione delle condizioni materiali di vita nel segno della giustizia sociale.
E' con grande orgoglio, dunque, che rivendico di aver fatto parte di questo movimento e di continuare a sostenerlo!
Voglio anche fare chiarezza sulla mia situazione.
Come è stato ampiamente sbandierato sui media di destra, Aler reclama un credito di 90.000 euro nei miei confronti come "indennità" per la presunta occupazione di una casa in via Giosuè Borsi a Milano, basandosi esclusivamente sul fatto che nel 2008 sono stata trovata al suo interno. Sebbene nei successivi sedici anni (!) non siano mai stati svolti ulteriori controlli per verificare la mia permanenza, né sia mai stato avviato alcun procedimento civile o penale a mio carico rispetto a quella casa, Aler contabilizza tale credito e non si fa scrupolo a renderlo pubblico tramite la stampa il giorno prima delle elezioni.
Un gran numero di individui e famiglie, spesso prive dei mezzi necessari per reagire adeguatamente, sono tormentate da richieste infondate di questo genere. Il totale dei crediti contabilizzati da Aler ammonta infatti ad oltre 176 milioni di euro! La pratica di richiedere esose "indennità di occupazione" agli inquilini, basata su presupposti a dir poco incerti, è una strategia utilizzata sistematicamente per spaventare gli occupanti e tentare di fare cassa.
Mentre molte, troppe persone non vedono garantito il proprio diritto all'abitare e non hanno alternative dignitose se non occupare - in una della città con gli affitti più cari, ricordiamolo sempre -, l'ente che dovrebbe tutelare questo diritto sembra essere più interessato a criminalizzare il movimento di lotta per la casa e gli inquilini piuttosto che a trovare soluzioni concrete.
Nei prossimi giorni condividerò alcuni dati e spunti di riflessione sulla questione abitativa a Milano e in Italia.
Ringrazio Libero & co. per avermi servito questo assist per riportare l'attenzione mediatica su un tema che mi sta molto a cuore, perché così cruciale per le classi popolari e i giovani.

MAI PIÙ GENTE SENZA CASA, MAI PIÙ CASE SENZA GENTE!

Nuovo disco per il gruppo italo svizzero degli Houstones, dal titolo "A + C", in uscita per Soppressa Records, Collettivo Dotto e Entes Anomicos. @Musica Agorà

iyezine.com/houstones-a-c

Houstones - A + C

Houstones - A + C - Nuovo disco per il gruppo italo svizzero degli Houstones, dal titolo "A + C", in uscita per Soppressa Records, Collettivo Dotto e Entes Anomicos. - Houstones

^{Massimo Argo (In Your Eyes ezine)}