<DocScrutinizer05>
heat dissipation is the key limiting factor
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<whitequark>
dos1: flash on SGS2 could actually be turned on for at least half an hour without any permanent damage
<whitequark>
and maybe longer
<whitequark>
and it would actually (temporarily) burn in your retina from 1.5m, so it's pretty bright
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<astr>
how many degrees would you say these leds are? 45° ?
<whitequark>
um
<whitequark>
it would get really hot
<whitequark>
more like 60?
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<astr>
whitequark, sorry not temperature, umm... angle of the light coming out of the led
<astr>
is that 60°C or °F
<astr>
i guess °C
<whitequark>
yes
<whitequark>
no idea about the angle
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<DocScrutinizer05>
whitequark: in HH?
<whitequark>
DocScrutinizer05: hm? what in hh?
<DocScrutinizer05>
astr: beam opening angle is obviously meant to have a uniform brightness of what the camera shoots. So for the usual F of a mobile cam more like 60°
<DocScrutinizer05>
whitequark: wasn't that hardware hacking congress this weekend?
<whitequark>
DocScrutinizer05: EHSM, yes. if you meant to ask whether I'm in Hamburg, then I'm there for 26-30 June
<whitequark>
right now at EHSM, in fact.
<DocScrutinizer05>
mhm
<DocScrutinizer05>
greetings from Doc to whomever it may concern! :-)
<whitequark>
I only really know the people who are also at #qi-hw...
<wpwrak>
DocScrutinizer05: you should watch .cl vs. br. amazing match. both teams very strong and playing as if the loser would face a firing squad.
<DocScrutinizer05>
watched parts of it
<DocScrutinizer05>
for all I know the loser could end in hell. NFC about that event actually
<DocScrutinizer05>
not even know if they fight for going to next round
<DocScrutinizer05>
anyway time for a bit of shopping before shops close
<wpwrak>
this is the 1/8 finals. so the loser goes home, the winner moves to the 1/4.
<wpwrak>
damn. they're going into an extension. how will i do my shopping, if .uy vs. .co is just two hours away from now ?
<wpwrak>
(loser going to hell) well, if the loser is brazil, that's pretty much the outlook. that world cup also has a significant political dimension in brazil. a lot of brazilians are not happy at all with the dubious infrastructure work that had been done.
<wpwrak>
(dubious) e.g., gigantic stadiums that will have no use once the world cup is over.
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<wpwrak>
and after the extension still 1:1, now the penalties ... impressive
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<whitequark>
DocScrutinizer05: so remember your laser printer idea?
<whitequark>
EHSM features just such a machine
<whitequark>
err
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<whitequark>
direct UV exposure with laser printer
<DocScrutinizer05>
sure, i always remember my ideas
<DocScrutinizer05>
and I'm used to find them done by somebody else
<whitequark>
it doesn't use a lens at all (I think they correct in software)
<whitequark>
also a single line of exposure is 80 rotations of the mirror
<whitequark>
so you get about 150µm of resolution due to slight variations in speed
<DocScrutinizer05>
:-)
<DocScrutinizer05>
how do they create the UV laser? blueray?
<whitequark>
definitely thinking about building one, because I'm kinda tired of fiddling with photonegatives
<DocScrutinizer05>
nice :)
<DocScrutinizer05>
you'll love it
<whitequark>
also there is a LOT of people interested in reproducible pcb photolitography
<whitequark>
actually two of them (100% of people I've talked to about this) also want homebrew multilayer
<whitequark>
and one already has working copper plating method using graphite-based ink
<whitequark>
I didn't find it earlier because it was in french...
<DocScrutinizer05>
another typ of the Doc: to check out the exposure and all, you can use a sheet of phosphorescent plastic
<whitequark>
DocScrutinizer05: there's actually no need for that. the photoresist very visibly changes color when exposed
<DocScrutinizer05>
yeah, but it costs real money
<DocScrutinizer05>
while for a quick go/nogo check you rather want to use sth cheaper
<whitequark>
eh, it's cheap, perhaps even cheaper than phosphorescent plastic + delivery
<whitequark>
quite sure it IS cheaper
<whitequark>
for like ten cm² of board, it's maybe a dozen cents
<DocScrutinizer05>
no it's not since you discard it after use
<whitequark>
I could use cat piss, it's phosphorescent too
<DocScrutinizer05>
no, it's fluorescent
<whitequark>
actually cat piss is THE reason consumer UV lamps are sold
<whitequark>
oh
<DocScrutinizer05>
like any piss
<whitequark>
right, fluo/phosphorescent, I always mix it up
<whitequark>
I now see what you mean
<whitequark>
mmmm, still need to buy it
<DocScrutinizer05>
get a emergency exit plastic sign
<DocScrutinizer05>
backside should be fine for this usecase
<whitequark>
never seen phosphorescent ones
<DocScrutinizer05>
since you never searched for them
<DocScrutinizer05>
fluorescent plastic comes in all forms and colors
<DocScrutinizer05>
for pretty cheap
<DocScrutinizer05>
err phosphorescent
<whitequark>
;D
<whitequark>
ok I'll look
<whitequark>
also these people were quite happy with my extensive documentation, and I'll probably be collaborating on documenting a complete modern homebrew PCB process with one of them later
<whitequark>
so I guess the work that went into lab.wq.org just paid off
<whitequark>
20 EUR, I could buy several square meters of resist
<whitequark>
OH
<whitequark>
wait, I just realized what you're actually suggesting
<whitequark>
you're suggesting this to debug optics
<whitequark>
I'm dumb.
<whitequark>
yes, indeed I would want something like that
<whitequark>
thanks
<DocScrutinizer05>
yw
<whitequark>
I've seen so many laser cut parts at the ehsm
<whitequark>
I now want a laser cutter pretty badly
<whitequark>
you see, there's a lot of cases laser cut
<whitequark>
in fact I have seen a case with rounded (d=40mm) corners made out of five pieces of acrylic and no glue at all
<DocScrutinizer05>
of course for exact tests a proper 10MP camera with infinite exposure time (can get simulated in software by adding 0.5s snapshots) and a plain sheet of paper works too
<whitequark>
one top plate, one bottom plate, a plate with a lot of thin slits that is bent around, and two more plates to latch top+bottom
<whitequark>
I could never make stuff like that with a mill, the cutters just don't work like that
<whitequark>
and even very simple cases with tabbed edges won't work, because I have to manually file down every corner and it just sucks
<DocScrutinizer05>
wait till you see the presentation of real professional grade 3D printing, e.g. with a bath of UV curing cyanometacrylate
<whitequark>
kickstarter is full of SLS 3D printers
<DocScrutinizer05>
or metal sintering 3D printer
<whitequark>
in a year or two they will be very cheap
<whitequark>
and in fact a presenter at EHSM was going to build a metal sintering 3D printer using his electron beam welder
<whitequark>
he even tried it with zinc oxide, but it just shat all over the vacuum chamber and into the pump
<DocScrutinizer05>
lol
<whitequark>
a great guy from Warsaw. invited me into his lab
<whitequark>
that reminds me, I need to book a hotel...
<DocScrutinizer05>
recently a company doing professional metal 3D for aeronautic etc (!!!) wen IPO (stock exchange)
<whitequark>
heard
<whitequark>
I think
<DocScrutinizer05>
their printers are a tad expensive
<whitequark>
there's a gaping hole where all the DIY metal sintering printers should be
<DocScrutinizer05>
yup
<whitequark>
I just wish vacuum equipment was cheaper
<DocScrutinizer05>
I wonder if sputtering could get done
<whitequark>
you need something heavy to sputter with
<whitequark>
and that's probably really expensive
<whitequark>
I mean, sputtering is apparently done using gold ions or smth like this
<whitequark>
argon, too, but it's not as efficient
<DocScrutinizer05>
or (attention, *weird*) vaporizing
<whitequark>
and really expensive
<DocScrutinizer05>
maybe the metal atoms could even get transported exactly into place by an electron beam?
<whitequark>
so you'd make the workpiece the cathode?
<DocScrutinizer05>
prolly only feasible for *really* tiny objects
<DocScrutinizer05>
yup
<whitequark>
I think the problem is that if you want it fast, you'd need high beam current
<whitequark>
and that melts / destroys workpiece
<DocScrutinizer05>
yup
<whitequark>
maybe if you machine, idk, wolfram
<whitequark>
tungsten?
<DocScrutinizer05>
well, the trick is to make the workpiece get hot enough to have nice integration of the metal atoms into a crystal, but not melt the whole thing down
<whitequark>
uh, I don't think you can grow a crystal like that
<whitequark>
it would be incredibly stressed
<DocScrutinizer05>
metal is a crytal maze, no?
<whitequark>
you'd have a very, very, very imperfect crystal
<DocScrutinizer05>
unless it's molten
<DocScrutinizer05>
yes, sure
<whitequark>
you could anneal it afterwards, I guess
<whitequark>
damn. so many cool ideas to work on
<DocScrutinizer05>
I'm more worried about effects like xray secondary radiation when operating with such types of electron beams ;-)
<whitequark>
that's at 10kv and higher
<DocScrutinizer05>
even 30
<DocScrutinizer05>
how do you create an electron beam of several Ampere strength?
<whitequark>
a big power supply?
<whitequark>
I mean, there's not exactly a limit. you can pump hundreds of amperes into a xenon continuous discharge lamp
<DocScrutinizer05>
aaah, right, it might have a impedance like a gas discharge lamp
<whitequark>
same principle here
<whitequark>
but you need very precise pressure control
<whitequark>
too high, and it sparks. too low, and beam dies
<DocScrutinizer05>
I was thinking absolute vacuum
<whitequark>
no beams in absolute vacuum
<whitequark>
and no such thing too
<DocScrutinizer05>
uhß
<DocScrutinizer05>
?
<whitequark>
well
<DocScrutinizer05>
what's that Braunsche Roehre then, CRT?
<whitequark>
any vacuum you can achieve on earth is not even close to simply outer space
<whitequark>
this guy explicitly says that if the pressure is too low, the CRT won't work
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<DocScrutinizer05>
sorry, for all I ever heard that's mere bs
<whitequark>
hm
<whitequark>
maybe
<whitequark>
oh, I realized the mistake
<whitequark>
you would only need some ions if you want cold cathode
<whitequark>
for hot cathode you can indeed have any kind of vacuum
<DocScrutinizer05>
for CRT in former times you even had ion traps to keep any residual gas atom in the CRT from damaging the fluorescent paint
<DocScrutinizer05>
nowadays vacuum is good enough so they don't need it anymore
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<DocScrutinizer05>
unlike the electrons the ions don't get diverted that much by the magnetic field, due to higher mass, and thus created a dark spot in center of CRT screen
<whitequark>
why would ions be accelerated towards the screen?
<DocScrutinizer05>
err, dunny, maybe because they are also electrically charged? Or because the electrons simply "kick" then?
<DocScrutinizer05>
see electromigration
<DocScrutinizer05>
dunno*
<whitequark>
I mean, the ions should be accelerated into the opposite direction
<whitequark>
electrons kicking them... hmmm, maybe that
<DocScrutinizer05>
https://de.wikipedia.org/wiki/Kathodenstrahlröhre#Strahlerzeugung >>Im nebenstehenden Bild ist das Strahlsystem einer veralteten Fernsehbildröhre mit Ionenfalle zu sehen. <<