ChanServ changed the topic of ##yamahasynths to: Channel dedicated to questions and discussion of Yamaha FM Synthesizer internals and corresponding REing. Discussion of synthesis methods similar to the Yamaha line of chips, Sound Blasters + clones, PCM chips like RF5C68, and CD theory of operation are also on-topic. Channel logs: https://freenode.irclog.whitequark.org/~h~yamahasynths
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<ejs__>
man i'll be so happy to get this sound card released, lol
<ejs__>
it's been a slog, but i knew that going in ;)
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<Foone>
cr1901_modern: PersistentCopy, it's an as-yet-unreleased tool for floppy imaging. it's basically win32 ddrescue for floppies, with a few floppy-specific feature
<cr1901_modern>
Hmmm, well that's no fun :P (unreleased)
<sorear>
i feel like at some point in the past we were promised machines that could read flux off a disk _without_ spinning it or subjecting it to much force
<cr1901_modern>
CT scanner, but for floppy disks
<cr1901_modern>
the disk doesn't spin... the read head does!
<Foone>
do I have to cool down my floppies to nearly absolute zero?
<Foone>
because liquid helium is expensive
<whitequark>
CT scanners don't use cryogenics
<whitequark>
it's basically X-ray with more FFT (please don't hit me, i'm trying to ELI5 as i can)
<whitequark>
i mean, technically you can build those without cryogenics too
<whitequark>
but, aiui, the resolution directly depends on field strength
<Foone>
yeah.
<Foone>
which is why they'd be really happy to have some liguid-nitrogen superconductors, since right now they gotta use helium and it's getting scarce
<whitequark>
i've actually wondered about building an NMR spectrometer. there's a paper about doing that with a limesdr and an arduino
<whitequark>
it's... disappointing, frankly. like, the magnets i can use already mean the resolution would be bad, but the paper *also* uses both of those devices in an intensely laborously hacky way
<cr1901_modern>
I was under the impression that once we run out of helium, that's it. No more MRI
<cr1901_modern>
Also, that DIY CT scan is adorable
<whitequark>
cr1901_modern: it's more complicated
<cr1901_modern>
Well, that's less dire than "nope, can't be done again."
<cr1901_modern>
The way I recall it was: "There's no known substitute for helium that's suitable for MRI and it takes too much energy to create more via fusion/fisson to be practical to make helium."
<Foone>
the tl;dr is that we don't actually have a shortage of helium. There's plenty of it, but for historical reasons no one was capturing it to sell it, because it was too cheap
<whitequark>
you can do MRI with weaker magnets that can be cooled with LN2 (not to mention all the weird research ideas that people keep trying)
<Foone>
it's not anymore, and suddenly the price has skyrocketed. now that it's worthwhile to capture and sell it, it will be
<sorear>
you can distill it from the air (or rather, from commercial neon which is already the lowest-boiling fraction of air). nobody does this because petro-helium is 100 times cheaper
<whitequark>
but also what Foone and sorear say
<cr1901_modern>
Hmmm
<Foone>
but yeah, you get helium alongside natural gas, and so far helium has been so cheap that we just vent it off
<Foone>
it's actually because of WW1.
<whitequark>
wait. WW1?
<whitequark>
WW*1*?
<Foone>
yeah
<whitequark>
tell me more
<Foone>
post WW1 we wanted to make sure we had plenty of helium stored for airships
<cr1901_modern>
I can't imagine why... :P
<whitequark>
lol
<cr1901_modern>
(answer for those who don't know: hydrogen is flammable)
<Foone>
basically there was a place that made sense to store helium in, and a bunch of money was given to nearby natural gas fields to separate out their helium and store it there
<Foone>
a billion cubic meters of helium later, the government was like "hang on why are we spending so much money on this?" and started phasing it out and selling it all off
<Foone>
but the end result is that helium has been super-cheap since the mid-90s because the US government had a BILLION CUBIC METERS of spare helium
<sorear>
I wonder how much of a return hydrogen will make as a lifting gas, especially for non-human-rated vehicles
<cr1901_modern>
And now we don't? Also, does helium have that property where it eats through its container causing it to eventually fail (there's a term for it)?
<whitequark>
helium does not cause hydrogen embrittlement
<cr1901_modern>
^Thank you
<sorear>
hydrogen embrittles most metals but that's less of an issue for plastics and textiles AFAIK
<whitequark>
it does however cause helium embrittlement
<whitequark>
for mostly the same reasons
<sorear>
both hydrogen and helium will diffuse at an appreciable rate through ~anything
<Foone>
but yeah. the helium reserves are running out and since it's been stupidly cheap since 1996, most natural gas fields have just been venting it. it's not worth collecting and selling
<whitequark>
the reason hydrogen embrittlement is a serious problem is that you might be welding, say, a bridge, and you might be using electrodes that aren't quite dry, and they'd have water
<whitequark>
in the welding arc, that water dissociates, and hydrogen gets into the steel at high temperature
<sorear>
between H2, B2H6, CH4, C2H2, HCN, H2O, HF, Ne, what is the Worst replacement lifting gas?
<sorear>
*NH3
<Foone>
Chlorine trifluoride (CIF3)
<cr1901_modern>
whitequark: I know at least one person who was experimenting w/ hydrogen gas and ended up blowing up a nice big hole in his warehouse b/c the canisters holding the gas failed. I guess they "weren't rated" for storing hydrogen?
<cr1901_modern>
That hydrogen is difficult to store b/c of things like embrittlement is a big reason to avoid it.
<sorear>
formula weight 92, would have to be at >900K to be buoyant and I think it decomposes before then
<whitequark>
cr1901_modern: hm, you know, disregard what i said. i don't know enough on the topic.
<Foone>
sorear: exactly! what could be a worse lifting gas than something much heavier than air, that's poisonous, corrosive, and exceptionally oxidizing?
* cr1901_modern
nods
<cr1901_modern>
sorear: I would THINK that in the past 100 years we've come up with ways to make H2-powered flight safer, but the storage problem remains. But hey... I'm guessing 100 years ago we had the same damn problem.
<cr1901_modern>
In addition to, ya know, the airships catching fire.
<Foone>
it's the one mentioned in Ignition! as possibly creating metal-flourine fires and it's so reactive it'll set asbestos on fire.
<sorear>
Ignition! also has Hg(CH3)2 as a proposed propellent which makes ClF3 seem far more pleasant by comparison
<Foone>
and the main reason it's not ever been used in rockets is that Chlorine pentafluoride is similar but worse. it'll set platinum on fire.
* cr1901_modern
looks for the safety diamonds of all these
<Foone>
the safety diamond just says "if you're close enough to read this, you should be running in the opposite direction"
<sorear>
is there anything that has a perfect 4 4 4
<Foone>
10 MONTHS later. damn.
<cr1901_modern>
sorear: Yes, but I don't remember offhand
<Foone>
"It has a slightly sweet odor, although inhaling enough of the chemical to notice this would be hazardous."
<sorear>
dimethylmercury is unfortunately not a contact explosive
<sorear>
(diborane is on my list above and also a 4 4 3)
<Foone>
Pentaborane is a 4-4-4-W
<Foone>
it will poison you, set you on fire, explode, and it'll do it to the water vapor in the air
<cr1901_modern>
My God...
<Foone>
it also explodes on contact with halon so if you have a serious fire-suppressant system, you're still dead
<sorear>
the weakness of something like clf3 is that it reacts stoichometrically with close to everything, so the scope of damage of a spill is limited to the amount you spill
<Foone>
the US made around 2000 pounds of it in the 1960s and it wasn't until 2000 that they figured out a safe way to dispose of it
<sorear>
the interesting poisions are all very selective. you have *mumble* micrograms of acetylcholinesterase and it doesn't take much to jam all of them
<Foone>
it was considered as a possible fuel for the XB-70 but it's so toxic that even after burning in the jet engines, enough particles would remain that the exhaust would be lethal
<andlabs>
[00:48:31] <Foone>it was considered as a possible fuel for the XB-70 but it's so toxic that even after burning in the jet engines, enough particles would remain that the exhaust would be lethal
<andlabs>
yes I too want my rocket to disintegrate immediately upon ignition
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<Foone>
yeah I think the soviets found that problem as well. I think that's why the N1 never flew
<Foone>
except for the small parts that made it to high altitudes as they were thrown far from the launch site by the blast
<andlabs>
before the beirut explosion a few months ago all four N1 launches occupied four of the top five manmade non-nuclear explosions list
<andlabs>
good job russia
<andlabs>
the N1 is a prime example of political infighting gone wrong and the story behind that the actual reason why the soviets was never able to get humans on the moon
<andlabs>
and I would totally watch an honest the right stuff-style or hbo chernobyl-style movie about the soviet space program
<andlabs>
[00:42:14] <sorear>is there anything that has a perfect 4 4 4
<andlabs>
and I find myself googling this a few times now and there's a specific forum thread that keeps popping up
<andlabs>
and of course now I can't find it
<andlabs>
one problem is that the actual number given can vary based on who's doing the evaluation
<andlabs>
ah, found it by searching for 444 instead of 4 4 4