Anyone who has done an electronic engineering qualification will at some point have had to get to grips with transmission lines, and then if they are really lucky, waveguides. Perhaps there should be one of those immutable Laws stating that for each step in learning about these essential parts, the level of the maths you are expected to learn goes up in an exponential curve, for it’s certainly true that most of us breathe a hefty sigh of relief when that particular course ends. It’s not impossible to understand waveguides though, and [Old Hack EE] is here to slice through the formulae with some straightforward explanations.

First of all we learn about the basics of propagation in a waveguide, then we look at the effects of dimension on frequency. Again, there’s little in the way of head-hurting maths, just real-world explanations of cutt-off frequencies, and of coupling techniques. For the first time we’ve seen, here are simple and understandable explanations of the different types of splitter, followed up by the famous Magic T. It’s all in the phase, this is exactly the stuff we wish we’d had at university.

The world needs more of this type of explanation, after all it’s rare to watch a YouTube video and gain an understanding of something once badly taught. Take a look, the video is below the break.

youtube.com/embed/H09w5YSnpGI?…

It could happen to anyone of us: suddenly you got this inkling of an idea for a product that you think might just be pretty useful or even cool. Some of us then go on to develop a prototype and manage to get enough seed funding to begin the long and arduous journey to turn a sloppy prototype into a sleek, mass-produced product. This is basically the story of how the Fitbit came to be, with a pretty in-depth article by [Tekla S. Perry] in IEEE Spectrum covering the development process and the countless lessons learned along the way.

Of note was that this idea for an accelerometer-based activity tracker was not new in 2006, as a range of products already existed, from 1960s mechanical pedometers to 1990s medical sensors and the shoe-based Nike+ step tracker that used Apple’s iPod with a receiver. Where this idea for the Fitbit was new was that it’d target a wide audience with a small, convenient (and affordable) device. That also set them up for a major nightmare as the two inventors were plunged into the wonderfully terrifying world of industrial design and hardware development.

One thing that helped a lot was outsourcing what they could to skilled people and having solid seed funding. This left just many hardware decisions to make it as small as possible, as well as waterproof and low-power. The use of the ANT protocol instead of Bluetooth saved a lot of battery, but meant a base station was needed to connect to a PC. Making things waterproof required ultrasonic welding, but lack of antenna testing meant that a closed case had a massively reduced signal strength until a foam shim added some space. The external reset pin on the Fitbit for the base station had a low voltage on it all the time, which led to corrosion issues, and so on.

While much of this was standard development and testing fun, the real challenge was in interpreting the data from the accelerometer. After all, what does a footstep look like to an accelerometer, and when is it just a pothole while travelling by car? Developing a good algorithm here took gathering a lot of real-world data using prototype hardware, which needed tweaking when later Fitbits moved from being clipped-on to being worn on the wrist. These days Fitbit is hardly the only game in town for fitness trackers, but you can definitely blame them for laying much of the groundwork for the countless options today.

Who among us hasn’t at some point thought of building a little vehicle, and better still, a little off-road vehicle for a few high-octane rough-terrain adventures. [Made in Poland] has, and there he is in a new video with a little off-road buggy.

The video which we’ve paced below the break is quite long, and it’s one of those restful metalworking films in which we see the finished project take shape bit by bit. In this case the buggy has a tubular spaceframe, with front suspension taken from a scrap quad and a home-made solid rear axle. For power there’s a 500cc Suzuki two-cylinder motorcycle engine, with a very short chain drive from its gearbox to that axle. The controls are conventional up to a point, though we’d have probably gone for motorcycle style handlebars with a foot shift rather than the hand-grip shift.

The final machine is a pocket drift monster, and one we’d certainly like to have a play with. We’d prefer some roll-over protection and we wonder whether the handling might be improved were the engine sprung rather than being part of a huge swing-arm, but it doesn’t appear to interfere with the fun. If you fancy a go yourself it’s surprisingly affordable to make a small vehicle, just build a Hacky Racer.

youtube.com/embed/hdIBxKy-0YY?…

da Radio Popolare (19-7-2024):

Le colonie israeliane in Cisgiordania sono illegali. Lo ha stabilito oggi la Corte internazionale di giustizia con un pronunciamento storico, che ha chiuso un importante procedimento avviato nel 2022.
“Il popolo ebraico non è conquistatore nella propria terra”, ha subito commentato il premier israeliano Benyamin Netanyahu, mentre i ministri di estrema destra Itamar Ben Gvir e Bezalel Smotrich hanno risposto chiedendo “l’annessione” di larghe parti della Cisgiordania.
Il parere della Corte era stato formalmente richiesto dall’Assemblea generale delle Nazioni Unite a proposito delle conseguenze legali dell’occupazione da parte di Israele della Cisgiordania e di Gerusalemme Est. Sentiamo Chantal Meloni, docente di diritto penale internazionale alla statale di Milano: radiopopolare.it/riassunto-del…

slowforward.net/2024/08/08/bts…

slowforward

2024-08-08 17:17:29

English below

slowforward.net/wp-content/upl…

“Welcome to Hell” è il rapporto più completo e autorevole sugli abusi e le torture sistematiche nelle carceri israeliane dal 7 ottobre, redatto da B’Tselem, la principale organizzazione israeliana per i diritti umani, che ha trascorso mesi a intervistare dozzine di ex prigionieri palestinesi (quelli che sono sopravvissuti alle torture).
Il loro rapporto fa “appello a tutte le nazioni e a tutte le istituzioni e gli organismi internazionali, compresa la Corte penale internazionale, affinché facciano tutto il possibile per porre immediatamente fine alle crudeltà inflitte ai palestinesi dal sistema carcerario israeliano e per riconoscere il regime di apartheid sistematico che opera in Israele”.

slowforward.net/wp-content/upl…

“Welcome to Hell” is the most comprehensive and authoritative report on systematic abuse and torture in Israeli prisons since October 7, written by B’Tselem, Israel’s leading human rights organization, which spent months interviewing dozens of former Palestinian prisoners (those who survived torture).
Their report “calls on all nations and all international institutions and bodies, including the International Criminal Court, to do everything possible to immediately put an end to the cruelties inflicted on Palestinians by the Israeli prison system and to recognize the systematic apartheid regime operating in Israel.”

slowforward.net/2024/08/08/bts…

#ApartheidFreeZone #BTselem #Cisgiordania #detention #dirittiUmani #EastJerusalem #Gaza #genocide #GeruselemmeEst #humanRights #illegalità #illegalitàIsraeliane #imprisonment #Israel #Israele #israeliPrisons #Palestina #Palestine #prigione #prigioniIsraeliane #prigionia #rapporto #report #sionismo #starvation #torture #trial #WelcomeToHell #WestBank #zionism #zionistPrisons #zionists

b’tselem’s report on israeli prisons, “welcome to hell”: free downloadable pdf // il pdf (liberamente scaricabile) del rapporto di b’tselem sulle carceri israeliane

“Welcome to Hell” is the most comprehensive and authoritative report on systematic abuse and torture in Israeli prisons since October 7, written by B’Tselem, Israel’s leadin…

^slowforward

Lo scorso capodanno ho visitato Nagasaki e i suoi monumenti alla bomba atomica. Sono parecchio brutti ma commoventi, e ci sono ancora reduci che portano la loro testimonianza con un'ammirevole dedizione alla diffusione di una cultura della pace anziché della vendetta. Mi dispiace che per amor di Bibi il vendicatore gli europei si siano fatti indietro.

ansa.it/sito/notizie/mondo/202…

Israele non invitato,ambasciatori occidente non vanno a Nagasaki - Notizie - Ansa.it

TOKYO, 07 AGO - Gli ambasciatori dei Paesi occidentali, compresa l'Italia, salteranno la cerimonia per il 79° anniversario del bombardamento di Nagasaki dopo che Israele non è stato invitato. Lo riferiscono alcuni funzionari. (ANSA)

^{Agenzia ANSA}