#homecmos IRC log for Tuesday, 2011-11-22

bart416azonenberg, I did something insane00:09
bart416I made an arc speaker today00:10
bart416Needed 13 lab supplies to power it xD00:10
bart416Was drawing 73 ampere xD00:10
bart416arcs were exceeding 10cm though00:10
azonenberg73 amps at how many volts?00:16
bart416so roughly 2.2kW00:18
bart416without fet drivers btw xD00:19
bart416BJTs in push/pull as driver00:19
azonenberglol, 2.2 KW?00:19
azonenbergthats a heck of a sound system00:19
azonenbergHow much of that actually went into audio though lol00:19
bart416we were losing about 400W in thermal emissions00:19
azonenbergAs in, 400W in heat dissipated on the control board?00:20
azonenbergBecause i bet the arcs dissipated a LOT00:20
bart416on the FETs00:20
bart416But we reached 141 dB at 1m distance at one point00:20
azonenbergHow was the sound quality?00:21
bart416not that great00:21
azonenbergi forget, arc speakers are good at HF but suck at bass?00:21
bart416The FETs had trouble switching that much power00:21
bart416but above 100W using FETs isn't the best of ideas xD00:21
azonenbergyou mean BJTs?00:21
bart416nah, the FETs were having issues00:21
bart416the BJTs not so much00:21
azonenbergi thought you said no fet drivers?00:21
bart416yeah, we used BJTs to drive the FETs00:22
bart416in a push/pull config00:22
bart416we had to only allow the FETs on for fractions of a second or they'd fry00:22
bart416we were using all of them above recommended values xD00:22
azonenbergSo you were operating them in linear mode?00:23
azonenbergor just the Ron was too high00:23
bart416well, we were using a high voltage transformer obviously00:23
bart416But after a few microseconds it saturates00:23
bart416resulting in a DC shortcircuit00:23
bart416If that were to occur the FETs would blow00:24
azonenbergSo the problem was the transformer was underpowered for 2kW?00:24
bart416The only thing keeping the entire setup alive was the current limit of the supplies though heh00:24
azonenbergThe whole thing just sounds like a terrible idea00:24
bart416you constantly saw the current limiter indicator turn on heh00:24
bart416and you could follow what FETs were doing the job on the meters of the supplies (they still have analog meters in them cause it's easier to spot certain things on those if you were wondering :P )00:25
azonenbergReminds me of the time I tried arc welding/soldering with a 5A 30V benchtop PSU00:25
azonenbergusing really narrow solder as the electrode00:26
bart416or endeavour wasn't helped by the lack of a LRC meter that could determine the self inductance of the transformer00:26
azonenbergi actually almost got a joint once lol00:26
azonenbergmade some spectacular sparks and burned the scrap PCB i was testing on00:26
bart416we tried a q meter as well, that one also failed00:26
azonenbergbut the 0603 cap i tried soldering was too big00:26
azonenbergmaybe on 0402 or 0201 i'd have a chance00:26
bart416We ended up having to use a network analyzer to find the impedance >_>00:26
azonenbergum, wtf00:26
azonenbergYou guys are crazy00:27
azonenbergNot that I'm not too00:27
azonenbergjust saying :p00:27
bart416The q meter didn't go low enough in frequency to be able to find the value, lol00:27
bart416We had to try a few network analyzers though00:28
bart416Only the old HP one delivered heh00:28
azonenbergYou mean like mHz?00:28
azonenbergyes, thats a lowercase M :P00:28
bart416Dunno, I didn't do the math00:28
bart416I was too busy preventing the FETs from melting each other00:28
bart416We were using large metal bars as cooling fins00:30
bart416worst part was, one of our professors was like "wtf are you guys doing?"00:30
bart416We were expecting to get shouted at at that point00:30
azonenbergand what happened?00:31
bart416He gave us a couple of high voltage probes so we could hook up a scope to the output end of the transformer xD00:31
azonenbergVery nice00:31
bart416Actually quite interesting waveforms00:31
bart416Though luckily we put our entire setup in our faraday cage00:32
bart416And you want to know the worst part?00:33
bart416TI makes FETs that can switch this sort of load on their own...00:33
bart416http://www.ti.com/lit/ds/symlink/csd17307q5a.pdf <-- like if we had used this one we could have gone to 92A00:35
azonenbergyay TI00:36
azonenbergGo buy better parts next time?00:36
bart416best part is the price of that thing lol00:36
bart416we intend to xD00:36
azonenbergWhile you're having fun with HV00:36
bart416hough our next step is actually to use liquid nitrogen00:36
azonenbergget a nice big cap bank00:36
azonenberglike, 25 kJ or so00:36
azonenbergAnd discharge it all into an unsuspecting fruit00:36
azonenbergI can say from experience the result is quite impressive00:37
azonenbergThough you might not want to be standing too close ;)00:37
bart416If we use liquid nitrogen we don't have to give a fuck about this entire maximum switching time00:37
bart416the junctions can't die if they're at -180°C xD00:37
bart416But yeah, the entire setup was acting as one huge transmitter :S00:40
azonenberghow much EMI were you pickign up from it?00:40
azonenbergand how big a faraday cage do you guys have wherever you are?00:41
bart416uhm, how big is our faraday cage, with or without the anti reflective spikes?00:42
bart416counting with them, about 2m high, 6m long, 4m wide.00:42
azonenbergok, thats loarge lol00:42
bart416Without, 3m high, 8m long, 6m wide00:42
bart416A lot of RF research goes on there so yeah00:42
bart416They actually need it00:42
azonenbergI see00:43
bart416We actually have a remarkable amount of RF equipment00:43
bart416Quite a lot of high power transmitters, excellent receivers00:44
bart416Loads of network analyzers that go really high in frequency00:44
bart416Scanners that most colleges/universities would commit a murder for00:44
bart416We also have a few of the network analyzers that go low in frequency00:45
bart416(Lower than 1Hz)00:45
bart416Most of it HP/Agilent, Tektronix and R&S00:46
azonenberg<1 Hz? How long do those things take to get a measurement00:46
bart416I'd say there's a few million euro worth of equipment in there00:46
azonenbergi was gonna say00:46
bart416We also have quite a lot T&M prototypes though00:47
bart416So you shouldn't be amazed if the front panel comes lose00:47
azonenbergYay prototypes00:47
bart416Actually, can't complain00:47
Action: azonenberg remembers fun times with semiconductor prototypes00:47
bart416Agilent prototype devices are not a bad thing, insane measurement ranges lol00:48
bart416"oh yeah I want 10 GSa/s"00:48
bart416^stuff like that00:48
bart416But the bastards feel the need to not let use in that lab until this year >_>00:48
azonenbergThey dont want to share the toys00:49
bart416I guess00:49
bart416Sort of understandable though00:49
azonenbergYou mean the fact that it probably costs six or seven figures?00:49
azonenbergThe guy at the RPI cleanroom who runs the FIB is very protective of it00:50
azonenbergnobody is allowed to touch it except under his personal supervision00:50
bart416Well yeah, they didn't actually have to pay for most of it00:50
azonenbergunless they have hundreds of hours on the SEM00:50
azonenbergwith no problems whatsoever00:50
bart416Well yeah, most of our equipment was sponsored or donated00:50
azonenbergThe SEM is a zeiss supra 55 that we got for what i'm told was a steal00:50
azonenbergit was included as almost a freebie when they bought the FIB00:50
azonenbergWhich was full price around $1.5M iirc00:50
azonenbergThe supra was used, a demonstration model that was well taken care of but not brand new00:51
azonenbergprobably would have sold for a paltry quarter million00:51
bart416demonstration models aren't all that bad if they're not abused00:51
azonenbergThe guy who runs the SEMs used to work for zeiss00:52
azonenbergHe knows his stuff00:52
bart416same for spectrum analyzers or DAQ cards00:52
azonenbergAs in, he was a lead engineer00:52
azonenbergwho did demonstratoins of their top-of-the-line equipment00:52
bart416Ever had the fun of playing with one of those 20000 euro DAQ cards?00:52
azonenbergand got to take the supra home to RPI's cleanroom when they finished demoing it00:52
azonenbergAnd no, i havent00:52
azonenbergi dont do much daq00:52
bart416one of my class mates had to use that >_>00:53
bart416I'd be scared as hell00:53
azonenbergyou mean that you'd break it?00:53
azonenbergYeah, i'm always paranoid on the SEMs00:53
bart416They're fragile as hell00:53
azonenbergEspecially the old Jeol00:53
azonenbergWhich isn't worth nearly as much00:53
azonenbergBut the supra has a camera inside the chamber so you can see if you're about to smash the sample into the objective00:53
azonenbergNo such luck on the jeol lol00:53
azonenbergAt least, the old tungsten one00:54
bart416I mean, I know those network and spectrum analyzers aren't that fragile, infact you can jam the input probe into the power socket and it'll probably be fine, but still00:54
azonenbergthe jeol FESEM does have one, i think00:54
Action: azonenberg wants a FESEM at home00:54
bart416But you probably understand what I mean?00:54
bart416My scariest experience was operating a synchrotron though00:54
azonenbergi've used equipment that costs more than my college degree did :p00:54
azonenbergand how so00:54
bart416Uhm, you're operating a device that accelerates sub atomic particles to a respectable fraction of lightspeed and then smashes them into something...00:55
azonenbergwhat i mean is, how automated is it?00:56
azonenbergin terms of the probability of, idk00:56
azonenbergpointing the beam somewhere other than the intended target00:56
bart416Oh, that's not a problem00:56
bart416It's just, you need to decide when the beam is ready to be released onto the target00:57
bart416the power bill of operating one of those things for even a few minutes is nuts00:57
azonenbergyou mean directing it from the storage ring to the target?00:57
azonenbergAnd i see00:57
bart416I mean, sure you simply wait until you reached the calculated parameters00:58
bart416But at that point the decision is still up to you00:59
azonenbergI see00:59
bart416If you fuck up it has to gather up momentum again for a day or two00:59
azonenbergA day? o_O01:00
bart416you can't just switch it on again01:00
bart416After every use it needed quite some maintenance01:00
azonenbergOh lol01:01
azonenbergi thought you meant it took that long to accelerate01:01
azonenbergand maintenance how so?01:01
bart416Sample has to be replaced, source materials, verifying for contamination, ...01:01
bart416Reconfiguring the system also takes a while01:01
azonenbergi see01:01
bart416I can't imagine what the people who operating the LHC must feel in terms of stress01:03
bart416+ our synchrotron was fairly old01:06
bart416I mean, it wasn't bad for its job (material research)01:06
bart416But it wasn't unlikely that some part was going to fail01:06
bart416And some of the sensors were also unreliable actually now that I come to think of it01:07
bart416Actually, without the older technicians I doubt we could have kicked that thing to life01:08
azonenbergmaterial research?01:11
azonenbergnot physics?01:11
azonenbergSo what are you doing, testing how material X behaves when irradiated?01:11
Thetawavesso cold fusion is a real thing now01:12
West0nHave you ever had an issue with photoresist pooling up azonenberg01:27
West0nI got some spray on stuff01:27
West0nI spray it on evenly01:27
West0nAnd it always drys as a small pool01:28
azonenbergThats why i dont spray it01:28
azonenbergI dilute with acetone and then spin coat01:28
azonenbergif you keep spinning till its mostly solid (doesnt take long witih the surface area of a micron-thick film)01:28
azonenbergit doesnt have a chance to pool01:28
West0nWill plain dilution reduce pooling?01:35
West0nAny way to stop it without a spin coat?01:35
horizontallyazonenberg: how likely do you think it is to be able to spincoat hundreds of nanometers?02:15
azonenbergDilution will result in a thinner film02:15
azonenbergsince the viscosity and solids content are lower02:16
azonenbergand if you use a solution with a low solids content, low viscosity, and high RPMs?02:16
azonenbergi've gotten films sub-100nm of tantalum oxide02:16
azonenberggetting good uniformity at these scales can be a little tricky02:16
azonenbergBut it was a tannish color that for SiO2 would mean around 50nm02:16
azonenbergTa2O5 is higher refractive index so it was likely a bit thinner02:17
horizontallywow sub-100nm!02:17
horizontallyis polyamide usually a photoresist?02:17
horizontallyor just a coating?02:17
bart416azonenberg, since when is material research not physics?05:54
bart416The goal was to test the materials in extreme conditions05:54
azonenbergi see05:55
azonenbergand it's just that i've never seen matsci folks dealing with high energy particles05:56
soul-dhey azonenberg  you in usa ? :)05:56
azonenbergYes, I am05:56
soul-dsend that to your politicians05:56
soul-dthast bradly manning05:56
azonenbergShould I know who that is?05:57
azonenbergOk, some soldier05:57
soul-dmaybe that pic does ring a bell05:57
bart416It's rather important to know how materials behave if you're going to irradiate them05:57
soul-doh he released the wikileaks thing05:57
bart416Or worse :p05:57
azonenbergOh, that guy05:57
soul-dand that  movie where american soldiers05:57
soul-dplay cod05:57
soul-dbut 18 month's of solitary confinedment american way ?05:58
azonenbergFYI i do not endorse any politician currently in office05:58
azonenbergI abstained in the last several elections because i disliked all of the candidates enough i couldn't vote for them in good conscience05:58
bart416<soul-d> but 18 month's of solitary confinedment american way ? <-- clearly yes05:58
azonenbergSo by abstaining I have the satisfaction of knowing that no matter who is in office05:58
azonenbergI didn't vote for him05:58
soul-dheh  yeah  most  of time doesn't realy mather05:59
soul-danyhow thats off topic  just woke up found this news   kinda distrubing  that people that  show mistakes get treated this way   it shows the mentality of people in power06:01
azonenbergThat show mistakes?06:01
azonenbergOr that swear an oath to protect their country and then violate that trust?06:02
azonenbergBecause he's a pretty clear example of the second06:02
soul-dyou think it's ok for us  soldiers  to go on shooting  randomly  for fun of it ?06:02
soul-dand yes06:02
azonenbergBut it's supposed to be handled through disciplinary channels06:02
soul-dbelieve that yourself06:02
azonenbergAnd going outside the chain of command is not your place06:02
soul-dyeah round about talk06:03
azonenbergThe point is, if you see something you think is wrong you're supposed to contact your commander06:03
soul-dthat is typical Rhetoric  relegious way of thinking06:04
azonenbergnot the nearest newspaper/leaker you can find06:04
soul-dthats doesn't work on that scale06:04
soul-dhe will be just replaced  and afther a bit fired and moved out the system06:04
azonenbergAnd guess what, in war people make mistakes06:04
azonenbergBut there's no need to parade them around the world06:04
azonenbergYou discipline those involved but that's the end of it06:05
azonenbergI guarantee for every publicly reported incident there were ten more that never saw the light of day06:05
azonenbergwhile those involved were still held responsible06:05
soul-di like to check that  end of story06:06
soul-dcause thats not how the dark world goes around06:07
azonenbergBut guess what06:08
azonenbergWho appointed you the army's babysitter?06:08
azonenbergI thoguht so06:08
soul-dthe army exists for sole purpose of me06:08
azonenbergAnd if you can't see the whole picture (read: higher up the chain of command) how do you know what you're actually seeing?06:08
azonenbergFor all you know it's a training exercise on how not to act06:10
soul-dthats the point if they don't tell me how i know they don't have other interest  how do i know   people are not signing up so they can kill  random people (they do )06:11
azonenbergYes, they try to weed them out in training but some will always get through06:11
soul-dyeah  like most things06:11
soul-don 9/11 where trainings acts06:11
azonenbergBut the same could be said of any military06:11
soul-dand they din't know the difrence :')06:11
soul-di see your point06:11
azonenbergSo who gains from this? What's done is done06:12
soul-dyou do know they simulated  9/11 on 9/11 ?06:12
azonenbergYou can't change it, all you can do is cause unnecessary chaos06:12
azonenbergSo best to let it lie and not cause even more harm06:13
soul-dsince  there is money involved  someone will profit06:13
soul-dall  weapons of egytian  revolution06:13
soul-dare  usa06:13
soul-dor backdrop06:13
azonenbergSo what? The russians sold quite a bit to the afghans06:13
soul-dto keep usa out i presume ?06:14
azonenbergThrough numeroous middlemen06:14
azonenbergSome of whom didnt do as told06:14
soul-dsince  they aren't there for the 15 trillion in material stuff06:14
soul-dneither  oil06:14
azonenbergEnough, this channel isn't here to talk politics06:14
soul-dmust be humentary stuff06:14
soul-dtrue wanted to get  cup off coffe  ages ago :P  only wanted to show  how usa treats  people without any kind trial  but i geuss in light of above thats all allowed :)06:17
azonenbergIf I leaked classified information to the press I'd expect no less06:17
soul-dbut this is why everone else in world  hopes on the demise of the us of a ?06:18
soul-dwel not hoping06:18
soul-djsut watching the live show06:18
azonenbergCertainly not cushy accomodations and release on bail while waiting for them to decide whether to execute me or not06:18
soul-dthe thoguht alone that  you consider  execution say's plenty06:19
soul-di din't even think of that06:19
azonenbergTreason in combat? That's been the standard06:19
azonenbergfor centuries06:19
azonenbergi can't say this case is any different06:20
azonenbergI don't know enough about the case to be certain of anyone's guilt but if convicted that's what I'd expect06:20
azonenbergWhat if the same person had leaked documents about troop movements to the enemy?06:21
azonenbergI would actually expect a summary execution on site06:21
soul-dthen you could have called it treason  for starters06:21
azonenbergWhat else would it be?06:22
soul-dbut  exposing people shooting radom people06:22
soul-dbut then again he din't know might be secret training op06:22
soul-dand funny thing is you can start war based on lie's  fabricate them with fake imagery   but then if someone in the war comes exposes  said military  it's treason :)06:24
azonenbergDoesnt matter how the war starts06:25
soul-dbut in end i don't care i  just wanted to mention that your country is crumbling apart  not  mine06:25
azonenbergOnce it's happening, you have to finish it06:25
soul-dthats not how it works :)  you can  even as american say " i am wrong "06:25
soul-dor " i have lost "06:25
soul-dwhatever hurts less06:26
soul-dbut thyen again starting somthign waht  can't be finished was the plan06:26
azonenbergWhat do you expect to do, say "oops, sorry"06:26
azonenbergwalk away06:26
azonenbergand expect to not be followed by a few thousand angry mujaheddin?06:27
soul-dhey  not my friends and family "proctecting america"06:27
soul-dthats my friend06:27
soul-dis your own fault06:27
soul-dmaybe not go in there and  starting to show guns ?06:27
soul-dnow they do hate you06:28
soul-dafther you killed  most of their family06:28
soul-danyhow someone read something about not going into discussion on political topics with american's  ;)  with that  ill grab some coffee and drop the subject  let you focus on smaller problems :P06:31
lekernelhigh speed photo, SEM, etc.12:58
horizontallyhey azonenberg, i found out we have a professional spincoater nearby that has ramp, etc. settings. i'm gonna use that but i don't want to use their expensive deep uv light source20:15
horizontallyso i'm going to try a halogen bulb (and maybe later a black light) and photoresist. is photoresist cancerous? what photoresist do you use? positive/negative? i heard you use glade to print the photomask, will anything do?20:17
azonenbergRe safety, read the MSDS for your specific resist20:22
azonenbergIn general you will want good ventilation when coating, the solvents are somewhat nasty20:22
azonenbergBut they are usually pretty safe to handle once dried20:22
azonenbergBut thats just a rule of thumb, the MSDS is the authoritative source20:22
azonenbergAlso, if you are not exposing in the same facility that you are coating20:23
azonenbergMake sure you have some way of moving the coated wafer around without exposing it to ambient UV light20:23
azonenbergor getting too much dust on it20:23
horizontallywe have a room with gold lights20:24
azonenbergYes, but are you exposing there?20:24
azonenbergOh, ok20:24
azonenbergI actually have two sets of lamps in my living room lol20:24
azonenbergone with white and one with yellow bulbs :p020:24
azonenbergThe yellow ones only cover a few key spots like the workbenches, not the whole room, but it's enough to get work done20:25
horizontallyi'm going to bring in my little cardboard box with aluminum foil on the inside and do contact lithography with a halogen bulb20:25
horizontallyit's an OSRAM 12V 100W that releases UV20:25
horizontallybut i think it's meant to be a white light source20:25
azonenbergI've used halogen lamps before20:25
azonenbergthey're wideband but get the job done20:25
horizontallywhy not a black light?20:25
azonenbergjust be advised they do run hot20:25
azonenbergblacklight is an option20:26
azonenbergmost of them peak around 365nm ish20:26
horizontallyso why did you pick halogen?20:27
horizontallyhow do you protect yourself from the uv in either case?20:28
azonenbergHalogen lamps dont emit enough UV to be a health concern, the bigger risk is the IR since its a fire hazard (the bulb gets quite hot)20:29
azonenbergBlacklight is also safe as long as you dont stare at the lamp for extended periods of time20:29
azonenbergthe ones you want to be careful around are short wave UV20:30
azonenberglike mercury vapor germicidal lamps20:30
horizontallyso i only want to deal with resists that are in that near uv area20:30
azonenbergi have those in a closed box20:30
horizontallybut i also want to be able to get down to like 50 nm thick layers20:30
azonenbergand UV goggles for the rare unavoidable exposures20:30
azonenbergFirst off20:30
horizontallyand since the color charts are repeatable, it's going to be tough to easily characterize that20:30
horizontallyer not repeatable but they repeat20:30
horizontallythey are periodic20:30
azonenbergthe injectorall resist is 365 to 405nm peaks sensitivity20:30
azonenbergSo its near UV20:31
azonenbergWhy in the world would you want a 50nm layer of resist20:31
azonenbergit won't block anything20:31
azonenbergusually you have a micron or so of it20:31
azonenbergthe only time you'd want a deep submicron film is if you are etching a film of comparable thickness20:31
azonenbergBut it never hurts to be thicker20:32
azonenbergthe only reason not to have a very thick resist film is that it limits your min feature size by a bit20:32
azonenbergbut unless you want submicron features20:32
azonenbergIn which case you are a bit beyond me ;)20:32
Thetawaveshave you guys seen this?20:33
azonenbergNo, I havent20:33
azonenbergThat, plus a bluray diode, could do some pretty cool stuff20:33
ThetawavesMoving Magnet Rotor. The solid rotor is rigider than coiled one, any harmful resonance does not occur. The carbon steel shaft is got from a junk motor (D=2, L=45), and neodymium magnets are got from scraped hard disks. The magnets are cut and bonded to the shaft and then shaped with a water-cooling grinder. The shaft should be thin and light as possible to minmize the rotor inertia.20:33
Thetawavesazonenberg, it will take significant effort to duplicate that work20:34
azonenbergI'm fully aware of that20:34
azonenbergI've been working on my current fab process for around a yea lol20:34
azonenbergAnd direct write litho would represent a quantum leap in mask fab capability20:34
horizontallyazonenberg: i want submicron thicknesses. i found a cool paper that covers how to control the thickness of the film i want to deposit in addition to the width and height20:34
Thetawavesgotta find the magnets20:34
horizontallyyou can find those at ace20:34
Thetawavesceramic magnets?20:35
horizontallyif you want a strong magnet, you're probably better off making your own electromagnet20:35
azonenberghorizontally: neodymium magnets are not hard to find20:35
azonenbergThetawaves: why, though?20:35
azonenbergsorry, horizontally20:35
azonenbergwhy do you need submicron films?20:35
horizontallyazonenberg: thicknesses. to investigate some things about lighting devices i can't go into unfortunately (NDA) :(20:36
azonenbergBut in that case you want a film of something else20:36
horizontallya professor i know is really into something cool that he won't tell me but he wants submicron thickness control20:36
azonenbergThat you can pattern with photoresist20:36
azonenbergThe resist should be as thick as you can possibly handle20:36
azonenbergIf you want a transparent layer of a submicron film i suggest glass (SiO2)20:37
horizontallyyou can't get 50nm thickness? or 100nm thickness?20:37
azonenbergEmulsitone Silicafilm can go down to that thin20:37
azonenbergPhotoresist would be hard20:37
horizontallybut i want to be able to take it off later too20:37
horizontallydo you use hf to get the sio2 off later?20:37
azonenbergI havent used silicafilm myself but it's not as dense as thermal oxide20:37
azonenbergdissolves quite quickly in HF20:37
azonenbergeven dilute (3% range)20:37
azonenbergso you can even pattenr it thorugh a photoresist mask using HF20:37
horizontallyi've had bad experiences with etching20:37
horizontallyi think it's that i'm not diluting stuff enough20:38
azonenbergI've been able to HF etch tantalum oxide20:38
azonenbergmy mask did degrade eventually, its very strong (maybe 10x lower etch rate than SiO2)20:38
horizontallyhow would you measure the thickness of your spincoated photoresist?20:38
azonenbergUsually, i dont :p20:38
azonenbergFor other stuff you can go off the color20:38
horizontallyi'm really hoping that method works because anything else is going to require me to invest more time in stuff i'm not super interested in anyway :\20:39
azonenbergthe vendor usually gives numbers for approximately what range you should be in20:39
azonenbergfor a given RPM and concentration20:39
azonenbergthen you can use the color to solve for the slight +/- 10% or so you might get due to process variation20:39
azonenbergand get a number good to within 50-100 nm20:39
azonenbergoften better, with practice20:39
horizontallywhat photoresist do you use again?20:40
Thetawavesi'd be able to build that galvo if i got the magnets20:40
West0nCommercial galvos are cheep20:40
azonenbergmy photoresist was gotten from injectorall.com20:41
azonenbergi believe it's shipley photoposit SP24D but they rebottled it so i cant be certain20:41
horizontallyhow did you settle on that one?20:42
horizontallyand where did you get it from? can you pick up photoresist from electronics surplus stores?20:42
azonenbergThe only one i could find from a nearby vendor20:42
horizontallyor like a hardware store?20:42
azonenbergi wish20:42
horizontallyfuckk :\20:42
azonenbergThey were the only company i found in the northeastern USA that sold it mail order in small volumes20:42
azonenbergplaces like fisher scientific etc will sell you just about anything20:42
azonenberg... by the liter20:42
azonenbergand idk if you know what the going price for a liter of photoresist is, but that stuff isn't cheap lol20:43
ThetawavesWest0n, apparently you are right20:43
horizontallyno? i saw some stuff for 10 bucks on google shopping20:44
horizontallyi don't know what volume20:44
horizontallymaybe i'm looking at developers20:45
azonenbergLooks like only one axis20:45
horizontallyso actually we have photoresist but it requires deep uv20:46
horizontally254 nm20:46
horizontallycan i still use the halogen bulb with that20:46
azonenbergUnlikely, look at the emission spectrum20:47
azonenbergits probqably a blackbody curve20:47
azonenbergi mean, it would *work*20:47
azonenbergBut you'd be looking at a very long exposure20:47
azonenbergYou might want to look at UV germicidal lamps20:47
horizontallyazonenberg: so if i had a bunch of halogen bulbs, that might make it faster?20:47
Thetawavesthat is a weird setup for a galvo20:48
horizontallybecause electricity is free for me (university pays so who cares)20:48
azonenberghorizontally: i think its a bad idea20:48
azonenbergeven for my photoresist it takes upwards of ten minuts for a pretty powerful lamp20:48
azonenbergin a contact exposure20:48
azonenbergthe only reason i can get away with using a halogen now is that i'm using the microscope lens20:49
azonenbergwhich squishes the output down to a tiny spot and makes it brighter20:49
azonenbergMy contact exposure box is actually 254nm20:50
azonenbergWhich is not optimal for my resist but its what the bulbs i had were20:50
azonenbergThe bulbs i have are unfiltered mercury vapor so they emit at 185, 254, 365, 405, 435, 546, 57820:51
horizontallyholy shit deep uv LEDs are like $250/led20:51
azonenbergYou do not want LEDs20:51
azonenbergthey are incredibly inefficient20:51
azonenberggo with mercury vapor lamps20:51
azonenbergsearch for uv germicidal lamps20:52
azonenbergi got two for like $10 apiece20:52
azonenbergthen hooked up a ballast and was good to go20:52
azonenbergThose do emit enough of the deep UV (185/254nm) that you want to avoid direct exposure20:52
azonenbergthey can cause both sunburns and eye damage20:52
azonenbergso you'll want to shield the enclosure and ideally wear yellow UV-blocking glasses when in use20:53
azonenbergi found a pair from edmund optics that are like five or six nines density below 500nm wavelength20:53
Thetawaveswhat kind of lens would you use for a galvo setup?20:53
azonenbergNo idea, i havent researched that much20:53
azonenbergits on the todo list but i've been very busy20:53
Thetawavesyeah i went to edmund but i'm at a loss for what i would need20:53
azonenbergNo clue20:54
azonenbergi have their catalog but i dont know what half the stuff in it is lol20:54
azonenbergthe only thing i've bougth from them was the UV goggles which were a pretty easy buy20:55
horizontallyazonenberg: how would you test that the bulb is working?21:04
horizontallyi guess you look at the current draw through the bulb21:04
Thetawavesi developed a visual model of the lenses required21:08
Thetawavesmount the setup on a stand above the spin coat machine21:09
Thetawavesyou would not have to touch it21:09
horizontallyazonenberg: also, the air is going to get pretty heated up by one of these UV bulbs right?21:10
horizontallyso in addition to the enclosure am i going to need some way of removing heat out of the enclosure?21:11
berndjhorizontally, personally my default opinion of pretty much any unpolymerized organic polymer chemistry is that it's carcinogenic. there are invariably radicals involved, which is never good news.21:26
berndjand just looking an DNQ for one, that looks rather a lot like a nucleotide base, too much for comfort21:27
horizontallyit seems so hard to believe that carbons and hydrogens with maybe a carbon ring or two through in can cause cancer21:28
horizontallybut i don't know anything about biology21:28
berndjgenerally, monomers = bad; aromatic rings = bad; other stuff: YMMV21:28
berndjand varying levels of "bad" of course; you get stuff that's guaranteed to give you cancer on even a little skin splash, and other stuff that doubles your risk if you bathe in it21:29
horizontallyfuck i hate nanotech21:30
berndjwe worked with one of the nastier things one in undergrad biochem - used for DNA sequencing - rather an intimidating feeling working with stuff like that21:30
berndjyou'll also get ozone from that sort of UV won't you?21:33
horizontallywell azonenberg linked me to a bulb that somehow doesn't make uv21:49
horizontallyi don't know how or why21:49
berndja UV bulb that doesn't make UV?22:07
azonenbergand what do you mean, doesnt make UV?22:10
azonenbergit was just a link of the spectrum22:11
azonenbergthey were advertising a UV-C bulb that filtered out the 185nm wavelength22:11
azonenbergwhich is what produces ozone22:11
azonenbergMy bulbs are unfiltered so you do get a nontrivial amount of it22:11
azonenberg254nm does not produce ozone afaik22:12
azonenbergalso, re the DNA sequencing nastiness22:12
azonenbergberndj: ethidium bromide?22:12
azonenbergberndj: also, DNQ is bound into the resin afaik22:13
azonenbergi dont think its free22:13
azonenbergThe MSDS for my resist lists the solvent as being a possible carcinogen but not the solids22:13
berndjethidium bromide sounds familiar, but not familiar enough to stand up and shout, "bingo!"22:14
azonenbergOrange fluorescence under UV22:15
azonenbergUsed for staining DNA22:15
berndjyou're right, DNQ is pretty much immobilized. i think mainly to avoid diffusion, which would ruin resolution. but i expect it isn't totally-100%-immobile22:15
azonenbergUnfortunately it has a nasty habit of injecting itself into any DNA within reach22:15
azonenbergI mean, you want t oavoid getting it on you22:15
azonenbergBut its nonvolatile22:15
azonenbergThe solvent is what you want to be more concerned about22:16
azonenbergas its both flammable and has vapors22:16
azonenbergThats actually the main thing i'm building my local exhaust setup for22:16
berndjoh, i was just about to say... isn't the solvent... water?22:16
azonenbergIn my resist is' a bunch of organic compounds22:16
azonenberg2-ethoxyethyl acetate, n-butyl acetate, then a few percent each of xylene and toluene22:16
berndjbut i think water has some major role in things?22:17
azonenbergWater is used in the reaction somewhere but i think it picks it up from the atmosphere22:17
azonenbergYou dont need much22:17
horizontallyman azonenberg knows so much22:29
azonenbergI just read a lot22:31
azonenbergand play around a lot22:31
berndjhe knows everything!22:46
berndjactually i meant to ask you, since IIRC you aren't really formally trained in EE (or are you?): how did you get into electronics, as in actually building stuff that works?22:47
azonenbergPlaying around22:52
azonenbergi was doing simple stuff with 555s when i was like 1222:52
azonenbergthen got out of it for a while due to lack of supplies22:52
azonenbergthen started doing more serious stuff with MCUs when i met some folks in the electronics club at school22:52
berndji'm stuck in no-man's land: 555s seem not worth doing, and MCUs way too intimidating!22:55
azonenbergsimple low-end PICs are not scary at all22:56
azonenbergyou can get them in DIP and program them in C22:56
berndjthat's probably what i should be doing22:56
horizontallyMCUs are intimidating? why? what's your background?23:04
berndjactual software and mostly only armchair electronics :-/23:10
berndjno, you're right; they really aren't23:11
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