highaltitude.log.20080321

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[00:04] <RocketBoy> night all
[00:04] <edmoore> ok bed
[00:04] <edmoore> cya later
[00:04] <natrium42> hi
[00:04] <natrium42> and bye
[00:04] <natrium42> :(
[00:04] <edmoore> lol
[00:04] <edmoore> well timed
[00:04] <natrium42> yeah, eh...
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[11:22] <Laurenceb> hey all
[11:23] <Laurenceb> I'm thinking of doing some more work on the zagi project, I'll try and get some boards made for the flight computer using pcbcart.com
[11:24] <Laurenceb> and swap to mage324p instead of the mega64 on the previous design
[11:28] <edmoore> a nice device!
[11:28] <Laurenceb> it is
[11:28] <Laurenceb> as is http://uk.farnell.com/1299316/semiconductors/product.us0?sku=TAIWAN-SEMICONDUCTOR-TSM2302CX&_requestid=58342
[11:28] <Laurenceb> for cutdowns :P
[11:29] <Laurenceb> 10A pulse, 0.45 threshold voltage !
[11:29] <edmoore> nice!
[11:29] <Laurenceb> I can make the board insanely small with those
[11:29] <edmoore> we've had lotsa luck with the logic level mosfets in to220 so we're sticking with them, but actually those devices are very nice
[11:30] <edmoore> am sure I could think of some apps :)
[11:30] <Laurenceb> yes, t0220 is just a bit big
[11:30] <Laurenceb> to*
[11:31] <edmoore> if you could get some logic level ones in those packages, i'd buy 100
[11:31] <Laurenceb> it is logic level
[11:31] <Laurenceb> but with the thermopile unit being so small, if I can make it work with my radio board and a small gps it would work in a really ssmall flying wing
[11:32] <edmoore> there's a link I must find for you......
[11:32] <edmoore> gimme a sec
[11:33] <edmoore> http://www.continentalctrls.com/
[11:33] <edmoore> have a look at the TGE
[11:33] <edmoore> it's wee
[11:35] <Laurenceb> nice
[11:35] <Laurenceb> but thermopiles are a bit easier
[11:35] <Laurenceb> and cheaper
[11:40] <Laurenceb> I'll swap to these for the voltage regulators - http://uk.farnell.com/1100656/semiconductors/product.us0?sku=MICREL-MIC5219YM5-TR
[11:41] <Laurenceb> rather than the to220 ones previously
[11:42] <Laurenceb> 500ma is nice :P
[11:43] <Laurenceb> I'm hesitant about using a switcher, want to keep it simple
[11:47] <Laurenceb> oh I was playing with some figures the other day, and its possible to run a small tesla coil directly off pwm from an avr clocked at 20mhz - you could do audio modulation really easily
[11:47] <Laurenceb> the pwm would be going at a few 100Khz
[11:48] <edmoore> yes, I believe the ones on t'bed normally modulate ontop of a 40khz switcher
[11:49] <edmoore> t'web*
[11:49] <edmoore> agree about the linears - a bit of payload capsule heating can't hurt
[11:49] <edmoore> will keep the radio xtal more stable, if anything
[11:50] <Laurenceb> yes, the switched mode supply seemed to be what screwed up on the rogallo
[11:50] <edmoore> need to eat some ice-cream now
[11:50] <edmoore> all in the name of science
[11:50] <Laurenceb> :D
[11:51] <edmoore> the polystyrene cases are so cool!
[11:51] <Laurenceb> I'm still at uni :(
[11:51] <Laurenceb> going home sunday
[11:51] <edmoore> easter lunch?
[11:51] <Laurenceb> hopefully
[11:52] <Laurenceb> just been moving my stuff back to my room from the lab, I "borrowed" a few components
[11:53] <Laurenceb> I now have a thermopile amp, might make a reflow oven
[11:53] <edmoore> I'm about to make one
[11:53] <edmoore> going to homebase soon to have a peek for something cheap
[11:53] <edmoore> and moddable
[11:53] <Laurenceb> cool, where are you going to get solder paste?
[11:53] <edmoore> rapid, I was thinking
[11:53] <edmoore> they had some last i checked
[11:53] <Laurenceb> ah sweet
[11:53] <edmoore> making stencils could be an interesting one
[11:54] <Laurenceb> yes, I was going to leave that for the first attempts, but maybe its wise
[11:54] <edmoore> it could be reason #278 to invest in a sherline mill
[11:54] <edmoore> oh same
[11:54] <edmoore> but in the long run
[11:54] <edmoore> if there's an easy way to do it, may aswell
[11:54] <Laurenceb> I'm wondering relay or rectifier and fets
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[11:54] <Laurenceb> or some fancy AC stuff even...
[11:54] <edmoore> for what?
[11:55] <Laurenceb> turning the heater on/off
[11:55] <edmoore> oh, the heat cointrol
[11:55] <edmoore> sorry was still metally on stencils :)
[11:56] <Laurenceb> I'm not sure what will happen if you use a rectifier with that sort of power... might muck up the mains a bit
[11:56] <edmoore> will consult instructable, the source of everything
[11:56] <edmoore> I'm happy to just do something tried-and-tested for this
[11:57] <Laurenceb> hmm might be a plan
[11:57] <edmoore> can make a nice GUI later
[11:57] <Laurenceb> I've never made anything with high voltage AC (aka mains)
[11:58] <edmoore> me neither, though I've been zapped hy it a few times
[11:58] <Laurenceb> hehe
[11:58] <Laurenceb> I once split acid over myself while making guncotton
[11:59] <edmoore> whoops
[11:59] <Laurenceb> it wasnt too bad, but as I frantically washed it off, all the water went over some plugs
[11:59] <edmoore> there's a greaqt photo of henry on his site
[11:59] <Laurenceb> and I got zapped
[11:59] <edmoore> lemme find it.....
[12:02] <edmoore> http://henryhallam.cjb.net/images/NaClO3.jpg
[12:02] <Laurenceb> ah cool henry has a site :P
[12:02] <Laurenceb> o no :(
[12:03] <Laurenceb> thanx bad :( poor henry
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[12:10] <Laurenceb> Rogallo :D http://henryhallam.cjb.net/images/hg/meflying1.JPG
[12:11] <edmoore> lol
[12:11] <Laurenceb> looks fun
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[12:15] <edmoore> http://www.circuitcellar.com/library/print/0704/Lacoste_168/index.htm
[12:18] <Laurenceb> he I have an AD595 from the lab
[12:19] <edmoore> I might use an arduino for this
[12:19] <edmoore> s'not complicated, saves faff
[12:19] <Laurenceb> just use a mega168 on breadboard
[12:19] <edmoore> I have an arduino!
[12:19] <Laurenceb> lol
[12:20] Action: Laurenceb wants an xmega avr
[12:20] <Laurenceb> they are only shipping to +10K buyers :(
[12:21] <edmoore> give it time
[12:21] <edmoore> they'd be great for a modem
[12:22] <Laurenceb> onboard DAC
[12:22] <edmoore> exactly
[12:22] <edmoore> and the usual dma bells and whistle
[12:22] <edmoore> s
[12:22] <Laurenceb> I've been trying to get my head around DMA
[12:23] <edmoore> well it makes sense conceptually, though can often be another cause of head-scartching come programming time
[12:23] <edmoore> but for still like, say, copying a large buffer from ram to an sd card, it's brilliant
[12:24] <edmoore> just the kind of thing you don't want the CPU to be wasting time on
[12:24] <Laurenceb> so you load in a pointer to your data, the size of the data, the adress of the hardware, and some control stuff from the hardware, and it fires off an interrupt on completion?
[12:24] <Laurenceb> ( I'm basing that on some avr32 code)
[12:24] <edmoore> well it needn't even fire off an interupt
[12:24] <Laurenceb> sure, but that helps
[12:24] <edmoore> you can just get, say, the dma to read adc1 and stick it in some address automatically on a timer and you never have to bother with it again
[12:25] <edmoore> you just read the address space and the latest reading is there
[12:25] <Laurenceb> yes
[12:25] <edmoore> mujic!
[12:25] <Laurenceb> how do you setup the timer?
[12:25] <edmoore> but the whys and wherefors seem to vary from chip to chip
[12:25] <edmoore> you'd have to have a look at the datasheet
[12:25] <edmoore> for the specific device
[12:25] <Laurenceb> it would have to be some sort of logic outside of the main system
[12:26] <Laurenceb> if you see what I mean...
[12:26] <edmoore> yes
[12:26] <Laurenceb> so you have configuration registers?
[12:26] <edmoore> so you'd initilise everything
[12:26] <Laurenceb> yes
[12:26] <edmoore> and there'd be registers
[12:26] <edmoore> yeah
[12:26] <Laurenceb> ok, pretty standard
[12:26] <edmoore> and then it should just stay as it is once you've set it all up
[12:26] <Laurenceb> so you'd be e.g "redirecting" the timer overflow flag to the dma
[12:27] <edmoore> yes
[12:28] <Laurenceb> too much stuff to make :S too many possibilities....
[12:28] <edmoore> I know!
[12:28] <edmoore> I'm just drooling over what I could do with a blackfin now
[12:29] <edmoore> Could make everything on a credit-card size pcb
[12:29] <edmoore> full EKF state estimation, flight control, housekeeping and logging with all the bells and whistles, modem, and an OS
[12:29] <edmoore> without breaking a sweat
[12:31] <Laurenceb> sure
[12:31] <edmoore> just need a year sabatical to make the damn thing!
[12:31] <edmoore> We've plenty of room left in our ARM anyway
[12:31] <Laurenceb> but .... I think I can run a zagi off a single mega324p
[12:31] <edmoore> so all these fantasies will have to be put asside for now :)
[12:32] <edmoore> the flight control is *never* the space consuming bit
[12:32] <Laurenceb> in fact I think you could run a zagi off a mega168, but I cant be bothered to optimise the code that much
[12:32] <edmoore> it's the BS like fat32, USBbulk and that stuff that takes up space
[12:32] <Laurenceb> yes
[12:32] <edmoore> anyway, luch
[12:32] <edmoore> cya later!
[12:32] <Laurenceb> at the moment my code is 22K (its up on the wiki)
[12:32] <Laurenceb> cya
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[16:23] <Laurenceb> hey edmoore
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[17:17] <neontube> afternoon all
[17:17] <neontube> long time no see
[17:17] <edmoore> 'ello
[17:17] <edmoore> how's life?
[17:17] <neontube> Ebay: 230234375388 - weather sat receiver if anyone is interested
[17:18] <neontube> not bad
[17:18] <neontube> extreamly busy at work though
[17:18] <neontube> in the middle of changing 430 schools from one internet provider to another
[17:18] <neontube> which includes 40,000 email accounts
[17:18] <neontube> & 300 + websites
[17:19] <edmoore> lol
[17:19] <edmoore> sounds like a fun afternoon
[17:20] <neontube> 3 weeks and email still isn't right
[17:20] <neontube> moved from a unix / IBM system to a windows exchange system,
[17:20] <neontube> we have to move over user accounts/passwords, and all emails in there account (its a web based system)
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[17:26] <edmoore> I want to build me a wee server now
[17:29] <neontube> as in Wii ?
[17:29] <neontube> or just small server :P
[17:31] <edmoore> small :)
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[17:46] <Hiena> Good evening!
[17:57] <edmoore> hi!
[17:57] <edmoore> just been hit by an awesome storm
[17:58] <neontube> as for small servers... i have a mac mini in the loft
[17:58] <edmoore> That would be ideal
[17:59] <edmoore> but equally for the money, you can do a lot if you DIY
[17:59] <neontube> indeed
[17:59] <neontube> 180 quid for an old mac mini though
[17:59] <edmoore> not bad
[17:59] <neontube> they are virtualy scilent
[17:59] <edmoore> tho I want RAID as it;s going to host all the important balloon and courseowrk and life SVN stuff
[18:00] <neontube> humm...
[18:00] <neontube> i personaly go for a manual backup to external HDD
[18:01] <edmoore> good idea, though increasingly I want to ditch all the laptop clobber and have an eeepc with everything accessible from the web
[18:01] <edmoore> but that's a bit off
[18:01] <neontube> fair do
[18:02] <edmoore> My current 15.4" laptop is a pain to lug around uni all day every day
[18:03] <neontube> indeed, you should see my laptop bag !
[18:03] <neontube> laptop - network tester - full set of tools - reference manauals + all my uni stuff !
[18:04] <Hiena> Ehem...
[18:04] <Hiena> Welcome to the 21th century.
[18:08] <Hiena> Hmmm... Bad weather fro the three day weekend: Checked, 3 BFR94 bough for nothing: Checked, A car with a fresh technical licence: Checked, RF modulator+CCD camera+GPS: Checked, Half finished ring-wing: Checked, Estimation: Somebody not will sleep this weekend...
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[18:14] <akawaka> morning
[18:14] <edmoore> morning
[18:15] <Hiena> Already?
[18:23] <edmoore> not me
[18:23] <edmoore> 18:23 round these parts
[18:24] <Hiena> Yup.
[18:30] <edmoore> woooooooooooo
[18:30] <edmoore> I got me a summer job
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[18:45] <akawaka> congrats
[18:49] <mc-> ed, what's your job?
[18:56] <edmoore> working for Vorticity systems doing the descent systems for extra-terreestrial landers
[18:57] <edmoore> They did the Huygens descent system, among other things, and are doing ExoMars atm
[18:57] <edmoore> space toys!!!
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[20:49] <mc-> nice job!
[20:57] <Hiena> mc-, last time you asked, who made the trashbag balloon, what i linked to you. That contraption builder was me.
[21:22] <mc-> very nice.
[21:28] <Hiena> No not nice. The 30 bag in one will be nice. ;)
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[21:37] <edmoore> Hi Rocketboy
[21:37] <edmoore> am just getting through some ice-cream
[21:37] <edmoore> I can confirm that the PCBs still fit in gu boxes.
[21:38] <edmoore> A useful confirmation, I'm sure you'll agree.
[21:38] <RocketBoy> mummmmm - yes
[21:38] <RocketBoy> what is the internal dimensions
[21:38] <RocketBoy> ?
[21:39] <edmoore> just shy of 90mm square
[21:39] <edmoore> and about 80 deep
[21:39] <edmoore> but will get some useful number later
[21:39] <edmoore> there's a roughly 5mm radius on the internal corners
[21:39] <RocketBoy> ok - sounds fine for the camera etc.
[21:40] <RocketBoy> how thick are the walls?
[21:40] <edmoore> 10mm ish
[21:40] <edmoore> Will go to the garage and attack it with verniers in a bit
[21:41] <RocketBoy> OK - np I just wanted to get an idea
[21:41] <edmoore> will need holes in the bottom for radio and gsm antenna
[21:41] <RocketBoy> It would be good to know the weight too
[21:41] <edmoore> do you think the gsm would be ok pointing down/sideways out the bottom?
[21:41] <edmoore> yes, I was looking for my scales
[21:42] <edmoore> to weight up as much of it as I currently have - gps, telit, pcb and box
[21:42] <edmoore> but they seem to have gone awol
[21:42] <edmoore> is there any advnatge to making antennas larger multiples of wavelengths?
[21:44] <RocketBoy> not as such - you can make co-linears (which are like dipoles stacked end on end) - these produce a more focused "beam" of RF
[21:45] <edmoore> ok cool
[21:45] <RocketBoy> but there is not much advantage for us - the ideal is no RF upwards - and sort of a sqished radiation pattern
[21:45] <edmoore> yeah
[21:45] <edmoore> though project #137 for a rainy day could be a pointing directional one back to a base-station
[21:46] <mc-> RocketBoy, there's a 5/8's whip or something that doesn't need a gnd plane, isn't there?
[21:46] <RocketBoy> but either the ground plane or the co-ax dipole are just about idea
[21:46] <RocketBoy> ideal
[21:46] <RocketBoy> yep
[21:46] <mc-> was trying to make an ant for 30m band
[21:47] <mc-> any suggestions?
[21:47] <RocketBoy> a loaded 5/8 whip is good - not sure on the radiation pattern though - I'll look it up
[21:47] <RocketBoy> 30m base station?
[21:47] <RocketBoy> (not balllon)
[21:47] <mc-> base station and for a balloon
[21:48] <mc-> don't have either
[21:48] <RocketBoy> well balllon is easy - about 5m of wire up and down from the payload
[21:48] <mc-> but have all the parts on order
[21:48] <RocketBoy> ooops - make that 2.5m
[21:48] <mc-> doesn't a dipole need a balun as well?
[21:49] <RocketBoy> ooo000oooops - 7.5m
[21:50] <mc-> 30/4 ?
[21:50] <RocketBoy> yeah ideally - but its not that much of an issue where there is no feeder - and there is a good match
[21:50] <RocketBoy> yeah 30/4 = 7.5
[21:51] <mc-> I don't know anything about baluns, so that's good I don't have to build one.
[21:52] <RocketBoy> acually this less than that - it depends on the actual frequency and the wire thickness - ormally 95% of 300/(4 * freq) in MHz will get it (I think)
[21:52] <edmoore> Ama gunna get me wunna dey'm ha alditood baluns
[21:53] <mc-> can I do the same trick on the ground, and put the receiver by the antenna?
[21:54] <RocketBoy> well - the simplest is just 7.5m of wire plugged in to the antenna socket
[21:54] <RocketBoy> It depends how complex and £££ you want to make it
[21:55] <RocketBoy> A 3 ele beam on a 200ft tower would be good
[21:55] <mc-> I wish..
[21:56] <RocketBoy> or http://www.m0rhi.co.uk/gallery/ssbfd05/100_0082
[21:56] <mc-> I guess if the ant can be raised up, it has better low angle radiation.
[21:57] <edmoore> It would be great to pitch one of those in churchill, and really set up a base camp for the duration of a mission
[21:58] <RocketBoy> Yeah - its all possible
[22:00] <RocketBoy> I'm amazed how well we do on the small yagi on a tripod - normally we can copy down to about 1000m
[22:01] <edmoore> at which point GSM kicks in
[22:01] <RocketBoy> yeah
[22:01] <edmoore> so says theory
[22:02] <mc-> found an 8m roach pole
[22:03] <RocketBoy> yeah good for a ground plane
[22:03] <RocketBoy> (on 10m)
[22:04] <RocketBoy> BBL
[22:06] <mc-> ed, did you get a soldering oven?
[22:06] fuzzylugnut (n=hush@24-116-155-170.cpe.cableone.net) joined #highaltitude.
[22:07] <mc-> I've got a hot air rework station, if you just soldering 1 IC.
[22:09] <fuzzylugnut> mc-: do you have all the different tips for the different chips?
[22:09] <akawaka> fuzzylugnut: micro-trak arrived yesterday
[22:09] <edmoore> mc, no, just thinking aboot it
[22:09] <mc-> no, that's expensive stuff. I just have a few basic tips.
[22:10] <edmoore> but I have a hot-air too so i should just use that really
[22:10] <fuzzylugnut> akawaka: yay! how do you like it?
[22:10] <mc-> is it a BGA chip?
[22:10] <akawaka> pretty cool
[22:10] <fuzzylugnut> mc-: yeah, I'm in the same boat... each tip is like $25 a piece
[22:10] <edmoore> I may be doing BGA stuff yeah
[22:10] <edmoore> and plenty of QFN
[22:10] <akawaka> doesn't like being powered from a plain old 9v battery though:)
[22:11] <edmoore> and MLF
[22:11] <mc-> or if it's Weller it $250 each
[22:11] <fuzzylugnut> akawaka: oh? did you ge the 300 or 8000?
[22:11] <akawaka> 8000
[22:11] <akawaka> FA
[22:11] <mc-> QFN are no problem
[22:11] <mc-> just watch it melt the solder, then stop
[22:11] <edmoore> normal solder or paste?
[22:12] <mc-> paste
[22:12] <fuzzylugnut> it's all over on ebay
[22:12] <mc-> but you can see the edges of a QFN
[22:12] <mc-> somewhere I saw you can buy stencils of the common chips
[22:13] <edmoore> oooh
[22:13] <fuzzylugnut> cool
[22:13] <fuzzylugnut> that'd be super handy
[22:13] <mc-> I think there was a link to a cheap stencil mfr on sparkfun
[22:14] <fuzzylugnut> you can etch them yourself too, the steel sheets are on ebay I think.
[22:15] <mc-> www.pololu.com from http://www.sparkfun.com/commerce/present.php?p=Stenciling
[22:17] <edmoore> paste seems quite expensive
[22:17] <fuzzylugnut> Cool
[22:17] <fuzzylugnut> doing it by hand sucks on big baords : (
[22:19] <mc-> you don't much paste, I've got a syringe of it in the fridge.
[22:19] <mc-> But it's probably out of date now.
[22:19] <fuzzylugnut> *nods*
[22:20] <fuzzylugnut> I keep mine in the fridge now. I had it out for a few months and it got reallly thick.
[22:21] <edmoore> I will give it a whirl
[22:22] <edmoore> need to make a biiiiiiiiig farnell order
[22:24] <mc-> why not rapid?
[22:25] <edmoore> they don't have some of the more obscure bits
[22:27] <mc-> is this your IMU?
[22:28] <edmoore> various
[22:28] <edmoore> partly that, some stuff for the flight computer, some specific fets for motor control, and some odds and sods
[22:29] <mc-> motor control for a gimbal?
[22:29] <edmoore> nope, some linacs
[22:30] <edmoore> tho could be used for a gimball
[22:30] <edmoore> it's basically a servo card
[22:30] <mc-> what's a linac?
[22:30] <edmoore> linear actuator
[22:30] <fuzzylugnut> linear accelerator in my world ; )
[22:31] <edmoore> yes, i was being a bit silly :p
[22:31] <edmoore> it
[22:31] <edmoore> whoops
[22:31] <mc-> I think I've worked out what that is for...
[22:32] <edmoore> yep!
[22:33] <mc-> you could point a telescope as well
[22:34] <edmoore> oh it's not for that....
[22:34] <edmoore> though actually I could make the hardware identical
[22:34] <mc-> I know, but I was thinking of other uses
[22:34] <edmoore> no I couldn't
[22:35] <edmoore> I'll force it into being useable for both
[22:35] <mc-> is the actuator something off-the-shelf?
[22:36] <edmoore> if I can find a suitable one, that'd be nice, yeah
[22:36] <mc-> or motor + leadscrew?
[22:38] <edmoore> OTS if poss
[22:39] <mc-> RC electric motor + gearbox would be lightweight?
[22:39] <mc-> or why not a servo?
[22:39] <edmoore> I'll need a bit more meat
[22:39] <fuzzylugnut> mmmm... meat.
[22:39] <edmoore> and don't want to spend on one of the really high performance digital coreless ones
[22:39] <edmoore> plus linear motion is nice
[22:40] <mc-> there's an open source servo group
[22:40] <edmoore> yeah, that's only an i2c digital backpack to normal servos
[22:40] <mc-> how fast do you need to move? or is that a leading qn?
[22:41] <edmoore> faster the better. Decent response and holding torque are what I'm after
[22:42] <fuzzylugnut> how about a linear motor?
[22:43] <mc-> they are heavy aren't they?
[22:43] <fuzzylugnut> yeah, they are
[22:43] <edmoore> yeah, just a linAc will do
[22:43] <mc-> is the 'instrument' balanced about its CoG?
[22:44] <edmoore> by definition!?
[22:44] <edmoore> oh sorry
[22:44] <edmoore> misheard you
[22:44] <edmoore> misread*
[22:44] <edmoore> I'm not sure we're talking about the same thing
[22:45] <mc-> if it's balanced, then holding torque is low?
[22:45] <edmoore> see above
[22:46] <mc-> I'm on 99
[22:46] <edmoore> I'm not :p
[22:46] <edmoore> it's just a random project
[22:46] <edmoore> the antenna will be steppers
[22:46] <edmoore> and far morte conventional
[22:46] <edmoore> more*
[22:47] RocketBoy (n=grunge@217.47.75.27) left irc: Read error: 110 (Connection timed out)
[22:50] <mc-> btw, are you coming to the space conf next weekend?
[22:50] <edmoore> yeah quite possibly. It'll depend on another thing but I'll come if I'm around
[22:50] <edmoore> also if George Whitesides is there that'll be another reason
[22:50] <mc-> did you email them, as I think they only have a few spaces left?
[22:51] <edmoore> nope - I just got an email saying plenty of spaces
[22:51] <edmoore> will email them
[22:52] <mc-> I've arranged to meet someone from the Xprize organisers
[22:53] <edmoore> oooh, whozat?
[22:53] <mc-> 99
[22:58] <Laurenceb> edmoore: nice job :P
[22:59] <edmoore> ty!
[23:04] <mc-> can an aerofoil be balanced to air pressure so it doesn't need much power to move it?
[23:05] <edmoore> not really
[23:05] <edmoore> it'll always be a function of angualr displacement
[23:05] <edmoore> and the force will tend to zero for small deviations about the midpoint
[23:06] <edmoore> but it's not really applicable to anything useful
[23:06] <Laurenceb> theres the moment of intertia of the vehicle to consider as well
[23:06] <edmoore> what are we talking about?
[23:06] <fuzzylugnut> pie? : (
[23:06] <mc-> if the shaft is in the middle of the foil, then there's equal pressure on each half? Or am I misunderstanding?
[23:06] <Laurenceb> nvm
[23:06] <Laurenceb> thats not relevant
[23:07] <edmoore> you'll have to elaborate mc-
[23:07] <edmoore> if it's a symetrical aerofoil generating no lift, then the pressures are equal on either side
[23:07] <mc-> sorry, if the bearing is in the middle of the aerofoil, then there's ...
[23:09] <mc-> I guess it is providing lift, then the CofPressure moves away from the centre of the aerofoil?
[23:10] <edmoore> it depends on what direction
[23:11] <edmoore> theoretically in the direction of lift the CoP can stay the same, just with reduced pressure above and increased pressure below
[23:12] <mc-> does that mean that a rudder doesn't need a large torque, if it's pivoted in the centre?
[23:12] <edmoore> oh I see what you mean
[23:12] <edmoore> no I think it's constant
[23:13] <edmoore> wherever you put it
[23:13] <edmoore> the cross-sectional area to the flow will still be constant
[23:13] <edmoore> so the same force will be applied on ino I'm talking rubbish
[23:13] <edmoore> in theory you're right, but flow instabilities will always ruin your day on that one
[23:13] <mc-> with a centre pivot, there's no restoring force, I think...
[23:14] <edmoore> it's unstable, yes
[23:15] <mc-> think there's a russian missile that uses multiple vanes (like a window shutter), so that there's low force required for guidance.
[23:15] <mc-> *I
[23:16] <mc-> but that's probably getting difficult to build...
[23:16] <edmoore> the contro, fins on the front of the eurofighter have a central pivot too
[23:16] <edmoore> but then it's designed to be unstable
[23:17] <mc-> I think most canards have a centre pivot
[23:18] <mc-> Burt Rutan's EZE did, I think
[23:18] <mc-> gotta go
[23:19] <edmoore> ok, talk soon
[23:19] <mc-> cya
[23:19] mc- (n=mfcastle@cpc4-glfd1-0-0-cust538.glfd.cable.ntl.com) left irc:
[23:19] <Laurenceb> http://www.sparkfun.com/commerce/product_info.php?products_id=8621
[23:19] <Laurenceb> ^ nice
[23:20] <fuzzylugnut> holy crap
[23:20] <fuzzylugnut> hot.
[23:21] <fuzzylugnut> price isn't bad either
[23:22] <edmoore> if the person who just left can ahem-hmm-throat-clearing-noises with them, then they'd be sh!t hot
[23:23] <Laurenceb> I'm just designing my new zagi board
[23:23] <Laurenceb> looking for a gps to use
[23:25] <edmoore> could probs do a lot worse than that
[23:25] <natrium42> Laurenceb, hopefully it works at high altitude, which many sirfIII don't apparently
[23:26] <edmoore> it won't
[23:26] <edmoore> I can tell you that for free
[23:26] <edmoore> hence3 my comment at 23:19
[23:26] <fuzzylugnut> awww
[23:26] <fuzzylugnut> bummer
[23:27] <fuzzylugnut> its so tiny and cute. : (
[23:27] <Laurenceb> anyone know where the sparkfun eagle library can be found?
[23:27] <edmoore> open circuits
[23:27] <edmoore> .com
[23:28] <Laurenceb> got it :P
[23:28] <Laurenceb> hmm where do librarys go on ubuntu?
[23:29] <natrium42> edmoore, grr, i still haven't reflashed that tiny gps module i got
[23:29] <natrium42> too many distractions
[23:29] <edmoore> tell me about it
[23:29] <natrium42> hehe
[23:34] <natrium42> in other news, i have almost decided to get an iridium phone
[23:34] <natrium42> just going to wait for a good deal
[23:34] <edmoore> standing on ebay with a quivering finger?
[23:34] <natrium42> yeah :(
[23:34] <natrium42> i am impulsive
[23:34] <edmoore> it's a happy feeling :)
[23:35] <natrium42> haha
[23:40] <natrium42> edmoore, i just think buying cheap products is a waste of money, hence not globalstar
[23:40] <edmoore> yeah fair enough
[23:41] <edmoore> sensible in the long run
[23:49] <edmoore> Laurenceb: have you a link to the linux SBC of yours?
[23:50] Nick change: fuzzylugnut -> fuzzy_food
[23:50] <Laurenceb> http://www.azzurri.com/store/products/atmel_ngw100.htm
[23:52] <edmoore> so cheap!
[23:52] <edmoore> what's the current consumption and dimensions?
[23:52] <Laurenceb> it doesnt need 12V
[23:52] <Laurenceb> 10cm*12, about 150ma @ 8V
[23:52] <Laurenceb> thats with the ethernet running and stuff
[23:52] <edmoore> nice
[23:52] <Laurenceb> my entire payload uses 200ma
[23:53] <Laurenceb> I've bypassed one of the diodes
[23:54] <Laurenceb> according to the datasheet for the switcher on the board, it will run off 6 or 7v
[00:00] --- Sat Mar 22 2008