ai is crypto 2 episode 373275

a hellish vision has been revealed to me

https://mander.xyz/post/47729411

potentially a common one, but we’ll only know after password leak from somewhere

i was thinking more like, thin external plastic shell and empty cells inside, perhaps with another thin plastic shell on inside, and internal metal shell (on plastic support?) fitting in snugly, for mechanical stability, idk 3dprinting

keeping leads short and nonmagnetic (dramatic reduction in skin layer depth) would be a good thing because of losses, but the longest object in capacitor would be just capacitor plates, and either way in wavelength terms it’s rather small. more precisely you can model it as open transmission line stub with some weird and low impedance, but it’s so small that you don’t have to. you can also make capacitor shorter and wider, or even add more layers like how vacuum variables are made. in nesting design you can get taper effect just by making inner layers longer

Found a piece about RFI and baluns, http://audiosystemsgroup.com/RFI-Ham.pdf multiple turns on ferrite aren’t really an option for VHF and up, ended up ordering extra beads (non-split)

The dielectric between the plates in this case is 0.4mm of ABS plastics (+ a bit of air in the 3d print layer lines).

in terms of losses, PP or PE is a bit better than ABS, teflon or FEP is a bit better than PP, but air is superior to either (this is part of the reason why foam coax is a thing). not sure which ones are printable, or whether it’s practical at this size, but try to introduce as many voids as possible (perhaps requires larger thickness of dielectric). it doesn’t matter much in your case, because of low power (warping of plastic because of excessive heat is probably not a problem). if your coax has solid dielectric, then by introducing enough air in 3d-print your variable might become less lossy than that

The Capacitors allows my 80cm diameter loop to tune from 20Mhz to 37Mhz. Sweeping the whole range is a bit slow due to the low RPM of the motor and takes about 6min. But that is kinda nice when fine adjusting to a frequency.

you have probably noticed that position vs resonant frequency relationship is rather nonlinear. you can get higher sweep speeds at lower end without losing much accuracy at higher end by tapering end of side plates into a triangle shape (it will get longer overall). it doesn’t matter much in your case, because it’s all approx monoband, but if you want to go multiband with this, then it’ll be a nice enhancement. similar effect happens when air variable capacitors have moving plates shaped in such a way that one end is longer than the other, and external edge has shape roughly like a section of logarithmic spiral. precise movement of variables like this is done by use of worm drive with large wheel

I am not sure what is causing this, but i assume it could be due to increase of dielectric losses in the capacitor getting bigger when more of the plates overlap because then the electric field has to flow thru a bigger area of dielectric, increasing the potential for losses.

loss tangent of dielectric is material property, that is ratio of equivalent loss resistance to capacitance should remain constant at given frequency. so i guess that losses should remain roughly the same, if dielectric is to blame, but at any rate lossy capacitor should make bandwidth broader and SWR lower. my guess would be that it’s a matter of coupling loop becoming wrong-sized or wrong-positioned at some point with change in frequency (try moving it up or down? there’s gotta be some optimum position for your entire range of interest)

it’s crazy how people memoryholed that (and japan doing the same, and a handful of other countries). or how until 2022 war norway wasn’t really thought of as petrostate by people who didn’t pay attention. or how ten years ago, if you said that putin bombed apartments to wage war on chechenya to win elections all to pardon yeltsin, people would think that you’re a crackpot

no there’s also racist twitter

i’ve collided with an article* https://harshanu.space/en/tech/ccc-vs-gcc/

you might be wondering why it doesn’t highlight that it fails to compile linux kernel, or why it states that using pieces of gcc where vibecc fails is “fair”, or why it neglects to say that failing linker means it’s not useful in any way, or why just relying on “no errors” isn’t enough when it’s already known that vibecc will happily eat invalid c. it’s explained by:

Disclaimer

Part of this work was assisted by AI. The Python scripts used to generate benchmark results and graphs were written with AI assistance. The benchmark design, test execution, analysis and writing were done by a human with AI helping where needed.

even with all this slant, by their own vibecoded benchmark, vibecc is still complete dogshit with sqlite compiled with it being slower up to 150000x times in some cases

yawn, i diagnose that LWer with weeb. this is something happening across entire industrialized world, causes being high performance mechanization of agriculture, old people being stubborn in regards to moving, lack of specialized work in countryside and couple of other factors. germany has patched their hospice staff shortage (not sure how effectively) with migrants, but japanese are way too racist for that. same thing happens in moldova, but you never hear sob stories about retired moldovans because they’re broke and nobody cares, while moldovan govt can’t really do much about it (because broke) to degree that it has not just economic and demographic, but even strategic effects. whole lotta drs strangelove in there

should have glued it in place smh

Skin depth is larger in aluminum but not enough to balance out its lower conductivity, copper is better material taking all into account, in practice both are good. If opposite was true we’d use lead or zinc for conductors. There are satellite microwave parts made out of aluminium (low weight) coated sequentially with zinc (bonding layer), copper (better conductivity), thin layer of silver (even better conductivity) and then gold (actually not thick enough to contribute, this one is for corrosion protection)

also ignoring that natanz was actually effectively airgapped, and was knowingly infected by another country’s contractor’s usb stick, working on behalf of dutch intelligence service

the thing with using aluminum tape is that you can get away with very small thickness, because current flows only in top tens of micrometers depending on band. you can just roll up, say, 5cm wide, 0.5mm thick aluminum tape and have riveted/brazed/spot welded short length of 2mm thick bar to the ends for connecting capacitor. the problem is with mechanical stability of this setup, which is why you see pipes and thicker bars, bicycle rims etc, and here you would need some kind of horizontal bars for loop to more or less keep shape

with braid you get a lot of contacts between wires, and i’m not sure that resistance of them would be low unless tire is fully inflated. keep in mind that copper in contact with some grades of rubber develops copper sulfide film. maybe you can put short U-turn within loop at end opposite of capacitor and have adjustable shorting bar there. adjustable capacitor is more common by far, because if you can adjust it widely enough, you can get to different bands

if you’re going for portable operation, wire dipole is probably the better way to go. cheaper, lighter, more efficient, you can roll it up and fit in your pocket. if you’re operating out of a car, you don’t need to fold magloop just lay it flat in the trunk

i’d expect shield to fray and core to bend with arrangement like this. if you just slide piece of pipe (can be rectangular, or U-shaped) it should be more durable. you’d be surprised at voltages developing there, even with 4W online calculators suggest something in 1kV range. 100W is over 5kV (voltage scales as square root of power)

btw if you don’t need it collapsible, consider using bicycle rim as loop, or some kind of wide aluminum tape, as it has much higher equivalent diameter than coax (less losses)

you can add in parallel small adjustable capacitor, made from two or maybe four coax cores with some kind of sliding conductive sleeve around them all (piece of copper pipe moved by screw) this way you should be able to tune to any channel within cb band

additionally, you made your loop suitable for higher power than was previously (magloops tend to be limited by voltage across capacitor). if you use coax with foam core, capacitance per mm will be lower still. for adjusting, you can get away with only clipping away shield with nail clippers

Because now you have to establish a complex supply chain and potentially large worker base in a place that’s potentially quite inconvenient for both, instead of a much simpler supply chain and smaller workforce.

i’m not sure why you think that it is the case. if you want to make aluminum, you just need a ship to come in and pile up alumina, then take up piled up aluminum. the process is decently automated these days and you avoid making hydrogen. if you want to make ammonia, then all you need is hydrogen that you use as soon as it’s made and nitrogen which is separated from air on demand. nitrogen fertilizers account for something like 2% of global primary energy use so it’s probably decently scalable. then you can ship out liquid pressurized ammonia, or convert it to ammonium nitrate which again you can pile up*. however with methanol you run into a Problem, because you need carbon dioxide, which means that you have to ship it from somewhere or capture in a massive installation. this immediately makes logistics of this entire enterprise harder. if you want to convert methanol to hydrocarbons then it takes some extra energy for little benefit (2x energy density) and some losses. to some degree, maybe it will make sense, but maybe it’ll be easier to just build up renewables where people already live

in that scenario biofuels get to serve much smaller segment than today in the first place so maybe it’s less of a problem. there are also things like biogas

I strongly feel that hydrogen is even more of a dead-end technology than these e-fuels. It is a right pain to store and transport and has rubbish energy density. There’s no future in the hydrogen economy. I’d bet we’re more likely to jump to artificial photosynthesis and fancy fuel cells than we are to see any substantial hydrogen infrastructure.

and you base that on what exactly other than vibes? there are applications where you need hydrogen directly as a reagent like ammonia synthesis, and these are probably most adaptable to this approach. methane is also proper PITA in terms of storage, yet we store it anyway because it’s cheap as a fuel. if hydrogen is cheaper than that, then it will be used where applicable. it’s easier to transport coal than electricity but not lignite; i don’t know how it will play out with hydrogen, but either way you can imagine a situation where hydrogen is generated onsite, or within pipeline distance, and used immediately or maybe with some storage worth hours to days. this fits iron smelting (DRI) nicely, today the fuel used for it is methane because it’s cheapest (process common in India). if hydrogen is cheaper than that, it will be used instead. other than that, applications where high heat is needed and where no electric heating can be used would be another use of hydrogen, like glassmaking and metal objects manufacture. hydrogen might be not disastrously bad option as fuel for transportation, because every step in manufacturing other fuels introduces losses; there are other tradeoffs

what do you want to fuel these fuel cells with? hydrogen is simplest option and most efficient (60% roundtrip efficiency or so). artificial photosynthesis is not a thing currently and strictly worse than combination of any energy source + conventional electrolyzer, because you have to combine not within single device but within single material something that will work as both. this also is only applicable to solar, not to wind or nuclear. some of these direct light to hydrogen schemes also only use UV only, and hydrogen is mixed with oxygen which is suboptimal, not to mention that main output of that work seems to be grant applications, while both electrolyzers and solar panels or wind turbines are available today, in bulk, straight from factory, and even more efficiently in decarbonization terms, these can replace coal-based electricity generation

regardless, main value of electrofuels today is in propaganda

* regular process starting from gas has carbon dioxide as a byproduct, so urea is another option, but with hydrogen it would have to be provided. it’s more expensive even today. maybe liquefied gas carrier could provide carbon dioxide and load ammonia on return leg, with some other dry cargo ship picking up that urea at some other time