whitequark changed the topic of #tinyqma to: design of an open hardware DDS-based QMA with a low-voltage dc/rf stage :: http://irclog.whitequark.org/tinyqma
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tangibleghost is now known as atonal440
<whitequark>
huh, turns out you *can* crack pyrex with thermal shock
<whitequark>
an unpleasant discovery when said pyrex contained conc nitric :p
<bofh__>
huh. I would ofc have assumed it to be possible, but I'm still surprised. Also do you need to heat the nitric acid at all/that much here?
<bofh__>
(also in terms of acids conc. nitric is literally above any conv. HF in terms of lab acids I don't want spilled anywhere).
<whitequark>
it actually didn't crack all the way through
<whitequark>
it has a circular visible crack, but the tube is intact and hermetic
<whitequark>
either way, i had it in a porcelain bowl, so nothing'd have happened, except nasty fumes
<whitequark>
I have spilled a few drops of HNO3 here and there. it doesn't react with PE. in fact, it was shipped to me in a polyethylene container
<whitequark>
and yes, I need to heat it. I need to heat it, wait quite a bit, and it *still* doesn't quite go all the way
<whitequark>
because I have to scratch like a millimeter of crap off the chip
<whitequark>
I'm not usre though if that's epoxy or just its carbonized residue
<whitequark>
bottom line, epoxy's fucking impossible to get off. it's mechanically tough and chemically resistant
<whitequark>
bofh__: right now i have boiled a chip in acid for 10ish minutes and the silicon is *still* covered in a sizable block of epoxy
<whitequark>
it is *definitely* not carbon
<bofh__>
if you've boiled it in acid for 10 minutes it's epoxy or worse
<bofh__>
guaranteed
<bofh__>
what's the chip itsself?
<whitequark>
93c64
<whitequark>
i've decided to just decap every atmel chip i have
<whitequark>
i want to figure out how to best do it, and also do some small chip at 100x
<whitequark>
in oil immersion
<whitequark>
since using that you can actually easily reconstruct the netlist
<whitequark>
but eg an atmega8 is just too large to comfortably do it by hand. 200+ movements of the stage
<whitequark>
bofh__: btw all chip cases are epoxy
<whitequark>
some have a pcb at the bottom for interconnect
<whitequark>
but pretty much every single one has epoxy on top
<whitequark>
and definitely every common case
<bofh__>
yeah I think this is why I suspect most decaping ops first have a mechanical pass to get most of the way before doing the acid bath
<bofh__>
also fucking hell
<bofh__>
this pisses me off every time I search a part
<bofh__>
and google is filled with literally hundreds of sites
<bofh__>
that are just endless lists of IC part numbers, "YOU CAN MAYBE GET A DATASHEET HERE!" and ads
<bofh__>
I don't even get why there's so many, the common thing is they have basically zero content beyond the part number
<whitequark>
yeah
<whitequark>
they scrape ... i think each other basically
<whitequark>
in hope of getting an rfq or at least some ads
<whitequark>
you know how there are lists of websites that list every phone number?
<bofh__>
I don't understand why it's more profitable to leave that up than to not, it can't actually be of any use.
<whitequark>
why is spam profitable?
<whitequark>
this is a form of search engine spam that's not actively harmful, so it's kept up
<bofh__>
spam generally tries to market something, or at least... like I can't see how this gets you any money.
<whitequark>
ok, it finally shattered entirely
<whitequark>
yay fumes.
<whitequark>
i really need a proper respirator
<bofh__>
I assume you're not doing this under like a fume hood or whatnot? :P
<whitequark>
sadly, not
<whitequark>
I just opened a window so it blows the fumes away from me
<whitequark>
It works surprisingly well
<whitequark>
I really need to make a portable fume hood though. I have some plans
<whitequark>
I'm not sure what to use
<whitequark>
glass is too heavy. acrylic can shatter with really sharp edges
<whitequark>
polycarbonate, maybe?
<whitequark>
on a frame from aluminium profile
<bofh__>
polycarbonate seems like it'd work. glass also runs the risk of shattering if slammed, which is easier to do because see heavy as hell point.
<bofh__>
now that you mention it I'm curious what the actual fixed fume hoods here use
<whitequark>
the ones in my school were soda glass
<bofh__>
also today I completely randomly revisited the TwinVQ tables and it turns out that once you scroll past the bark tables and what feels like very VQ table ever generated, you will run into this: http://pastebin.com/FVakFSPR
<whitequark>
wtf
<whitequark>
that is just disturbing on multiple levels
<bofh__>
I love how the function is actually named "very_broken_op()". Admittedly, that's very accurate.
<bofh__>
The thing I find the most disturbing is that in this codec, conformance is tied to a particular encoder implementation, so you have to be mostly bug-compatible.
<whitequark>
I haven't actually manage to dissolve the epoxy.
<whitequark>
It just... stays there
<whitequark>
should've probably burned it off instead of scraping, scraping never works
<bofh__>
(also speaking as someone who's written a shitload of audio codec code: "reference encoder" code is among the worst I have ever seen. Ever. High school students using C for the first time after a year of Java and no other programming experiencee usually write better code).