highaltitude.log.20090710

[00:45] <SpeedEvil> :) even
[01:58] Nick change: KingJ -> kingj
[04:22] <jiffe88> Laurenceb: you're planning to launch to orbit off balloons?
[04:23] <SpeedEvil> jiffe: 'planning' may be strong.
[04:24] <SpeedEvil> He's got some drawings in ms-paint, and a mathcad sheet for drag, and some bookmarks of suppliers.
[04:24] <jiffe88> heh, cool, thats a start
[04:25] <SpeedEvil> http://b3ta.com/questions/gyms/post477846
[04:29] <jiffe88> hah
[04:30] <jiffe88> at least he kept at it for 20 min, I would have lost interest after 5
[04:38] Nick change: jiffe88 -> jiffe99
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[08:01] <jcoxon> morning
[08:03] <rjharrison> Hey
[08:04] <rjharrison> Hi all
[08:04] <rjharrison> Just going off to work :(
[08:04] <rjharrison> Be a lot more fun to play a days HAB
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[08:42] <edmoore> jcoxon: morning
[08:42] <jcoxon> hey edmoore
[08:43] <jcoxon> just finished my payload box
[08:43] <edmoore> oh awesome
[08:43] <edmoore> pics or it didn't happen
[08:44] <edmoore> not nearly so much morse activity at the moment
[08:46] <jcoxon> not great propergation this time of morning i think
[08:46] <edmoore> lgot PA1MAX, i don't know what region that is though
[08:47] <edmoore> dutch
[08:47] <edmoore> very faint
[08:48] <jcoxon> how you decoding?
[08:48] <edmoore> just with fldigi
[08:48] <edmoore> PA1MAX tirelessly CQing
[08:48] <jcoxon> urgh, morse with fldigi is painful
[08:48] <jcoxon> go for cocoamodem
[08:49] <jcoxon> found it a lot better especially with hte PBH flights on faint signels
[08:49] <jcoxon> signals*
[08:49] <jcoxon> nearly was able to keep up with bill brown decoding by ear
[08:49] <edmoore> how do you set it up?
[08:49] <jcoxon> cocoamodem?
[08:50] <edmoore> yep
[08:50] <edmoore> can't get a waterfall going
[08:50] <jcoxon> oh
[08:50] <jcoxon> one sec
[08:50] <jcoxon> Window-> Config
[08:51] <jcoxon> click Inactive to change the state to active
[08:51] <jcoxon> after selecting the correct input
[08:52] <edmoore> ok
[08:52] <edmoore> loud signal from france now
[08:52] <edmoore> decoding well
[08:53] <jcoxon> for PBH as they only had a transmission every 10mins I set up audacity to autorecord
[08:53] <jcoxon> then ran it through cocoamodem multiple times adjusting the decode line to get the best decode i could
[08:54] <edmoore> so it's both F8AAM and P1MAX about 1khz apart, both CQing like crazy but not spotting each other
[08:54] <edmoore> maybe they don't like one another
[08:54] <jcoxon> you using qrz.com to look up the callsigns?
[08:55] <edmoore> yep, although they're neither registered
[08:55] <edmoore> but one if dutch and t'other is french
[08:55] <jcoxon> http://www.flickr.com/photos/jcoxon77/sets/72157621083447545/
[08:56] <edmoore> smart - can't wait for another flight!
[08:56] <edmoore> btw monday and teusday are now out next week
[08:56] <jcoxon> oh wx is rubbish then
[08:56] <edmoore> http://www.youtube.com/watch?v=S4IOQoZijIY - this is the guy CQing
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[08:56] <Laurenceb> hi
[08:57] <edmoore> i would like to learn morse
[08:57] <Laurenceb> inspector morse?
[08:57] <Laurenceb> :P
[09:00] <edmoore> K3DRO
[09:00] <edmoore> surely not
[09:00] <edmoore> that's transatlantic
[09:00] <jcoxon> what freq?
[09:00] <edmoore> 7.012.31
[09:01] <Laurenceb> edmoore: I came up with a workable n-prize launcher design
[09:01] <edmoore> i lost everything either side of it so I can't tell if it's K3DRO de P00H34D or something
[09:01] <Laurenceb> 8Kg hydrogen peroxide/kerosene from 30km then a martlet style spun solid
[09:02] <edmoore> now to gather the funds?
[09:02] <Laurenceb> heh
[09:02] <Laurenceb> well... theres not that much expensive stuff
[09:03] <Laurenceb> graphite nozzles
[09:03] <Laurenceb> analogue devices imu
[09:06] <jcoxon> edmoore, nothing on that freq now
[09:06] <edmoore> Pa1MAX got is contact
[09:06] <jcoxon> guess i was too late
[09:07] <Laurenceb> can anyone recommend a good solder station?
[09:07] <edmoore> they're all just talking about the weather
[09:07] <edmoore> Laurenceb: the best you can afford
[09:07] <jcoxon> thats what you do on HF
[09:07] Action: Laurenceb has had it with cheap soldering irons
[09:07] <Laurenceb> just spent 15 minutes trying to tin my iron
[09:07] <Laurenceb> probably partly due to it being leadfree
[09:08] <edmoore> find an old metcal on ebay Laurenceb
[09:08] <Laurenceb> ok
[09:09] <jcoxon> good rtty on 7.090
[09:11] <jcoxon> that said can't seem to decode it
[09:11] <Laurenceb> edmoore: have you even machined graphite?
[09:11] <edmoore> yes
[09:12] <Laurenceb> is the thought of machining a 3mm thick nozzle crazy?
[09:12] <edmoore> depends on how wide the nozzle is
[09:13] <Laurenceb> 5cm
[09:13] <edmoore> then yes
[09:13] <edmoore> could be tough
[09:13] <edmoore> jcoxon: can't find any rtty there
[09:14] <Laurenceb> edmoore: are there any better materials?
[09:14] <edmoore> could can make a graphite liner for something else stronger
[09:15] <jcoxon> very strong rtty 10.100
[09:15] <Laurenceb> how about two "liners" used as jigs
[09:16] <Laurenceb> or rather an inner liner thats inserted after milling out the middle
[09:17] <Laurenceb> then you take stuff off the outside
[09:19] <jcoxon> edmoore, wow didn't know that the 817 could listen to top band
[09:19] <edmoore> top band?
[09:20] <jcoxon> 137khz
[09:20] <jcoxon> 135.7 - 137.8
[09:21] <jcoxon> so thats 2200m band
[09:21] <gordonjcp> top band is 1.8MHz
[09:22] <jcoxon> oops
[09:22] <jcoxon> it can do that as wekk
[09:24] <edmoore> yeah - i was listening to radio for longwave (198khz) yesterday
[09:24] <edmoore> and i was accidently on ssb, picked up the carrier
[09:24] <edmoore> heard definite phase modulation on it
[09:25] <edmoore> and a quick google said that it provide an incredibly accurate Standard Time (capital S capital T) aswell as a few other things as a data stream modulated onto the carrier
[09:25] <edmoore> +/- 25 degrees phase modulation
[09:25] <edmoore> was trying to thing os something it could be usefully used for
[09:26] <rhjharrison> jcoxon day off?
[09:26] <jcoxon> i've finished :-D
[09:26] <jcoxon> did my exam on weds
[09:32] <jcoxon> did you guys know that wiki.ukhas.org.uk gets 35% of its visitors via my website
[09:32] <jcoxon> google only sends 23%
[09:32] <edmoore> want a medal :p
[09:32] <jcoxon> yes please
[09:32] <jcoxon> i think its time for a visitor traffic pdf
[09:34] <edmoore> go for it
[09:34] <edmoore> jcoxon: the 817 doesn't drop below 100khz
[09:34] <edmoore> that's annoying
[09:34] <edmoore> wanted to try and get the standard time signal from rugby, or wherever it is
[09:34] <edmoore> could sample that directly with a fast avr :)
[09:35] <gordonjcp> anthorn, now
[09:35] <edmoore> is that a bit northerer?
[09:36] <jcoxon> http://wiki.ukhas.org.uk/_media/analytics_wiki.ukhas.org.uk_20080627-20090710_dashboardreport_.pdf?id=start&cache=cache
[09:37] <gordonjcp> yeah, it's in Cumbria
[09:38] <edmoore> there's some activity from china
[09:38] <edmoore> in the same band as natrium
[09:41] <jcoxon> they don't hang around as long
[09:41] <edmoore> bbiab
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[10:07] <Laurenceb> isnt north korean radio broadcast from that station in cumbria?
[10:13] <Laurenceb> I heard they'd got airtime on one of the longwave transmitters
[10:21] <Laurenceb> edmoore: http://www.graphitemachininginc.com/pdf/brochure.pdf
[10:21] <Laurenceb> page 7
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[10:41] <jcoxon_> very cool: http://www.nasa.gov/multimedia/nasatv/on_demand_video.html?param=http://anon.nasa-global.edgesuite.net/qt.nasa-global/ccvideos/larc/mlas-launch.mov&_id=undefined&_title=undefined&_tnimage=test.gif
[10:57] <edmoore> jcoxon_: it's a massive parachute fetish
[10:57] <jcoxon_> i thought you'd like it
[10:58] <jcoxon_> i love the multiple stages of parachutes
[10:58] <jcoxon_> then when you think they've release them all the detach an even smaller section and deploy more
[11:03] <Laurenceb> seems excessively complex to me
[11:07] <jcoxon_> its not meant to be used though - so it needs to fit in with the rest of the systems
[11:13] <edmoore> using the parachute for the stage separation is a nice touch
[11:13] <edmoore> i assume it wouldn't separate at all otherwise
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[11:32] Action: jcoxon_ is reading about the HALO rockoon launches
[11:34] <rhjharrison> Holy crap that is a lot of parachutes
[11:34] Nick change: rhjharrison -> rjharrison
[11:34] <edmoore> fo sho
[11:35] <edmoore> parachute deployment is a lot of fun
[11:35] <edmoore> it's been an educational couple of weeks
[11:35] <rjharrison> it's more like paul daniels
[11:37] <edmoore> you know you're a geek when....
[11:38] <edmoore> You see on slashdot an article called 'what is the best mouse for programming?' and you instantly think 'er, dude, you don't need a mouse to use vi'
[11:38] <edmoore> and the very first comment on the article is 'er, dude, you don't need a mouse to use vi'
[11:38] <rjharrison> hehe is there another editor
[11:38] Action: Laurenceb uses gedit
[11:39] Action: Laurenceb informs RMS that edmoore prefers vi
[11:39] <edmoore> what the hell is rms going to do
[11:39] <Laurenceb> feed you his feet
[11:40] <edmoore> i'll just stand in some thistles so the bare-fotted beary can't get me
[11:40] <edmoore> beardy*
[11:40] <Laurenceb> lmao
[11:40] <rjharrison> vi is better than ed
[11:40] <rjharrison> ed really is hard core
[11:41] <jcoxon_> hmmmm a bug in my code
[11:41] <jcoxon_> time to fix it - fun fun fun
[11:41] <jcoxon_> bbl
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[11:44] <rjharrison> edmore for Badger cutdown do you try to predict landing position and cutdown when moving beyond a polygon of the UK. Or do you just work on distance from launch?
[11:44] <rjharrison> edmoore even
[11:44] <edmoore> we have done both - recently it's been very custom for each launch
[11:45] <edmoore> since the prediction got good, we basically just know it'll be fine, or give it a distance from launch site knowing what direction it'll be going in
[11:47] <rjharrison> Distance from launch is easier to implement. I was contemplating predition from the payload assuming roughly the same path on the way down. And taking a verctor from launch
[11:47] <rjharrison> vector
[11:47] <edmoore> you can do a hybrid which is easy
[11:47] <SpeedEvil> http://www.openstreetmap.nl/
[11:47] <SpeedEvil> openstreetmap conference
[11:47] <edmoore> if you want to port that to an avr SpeedEvil....
[11:47] <SpeedEvil> current presenteris a local government officieal
[11:47] <SpeedEvil> current presenter
[11:47] <edmoore> rjharrison: you can measure the winds on the way up
[11:48] <edmoore> say once per minute
[11:48] <edmoore> and assume they're the same on the way down
[11:48] <edmoore> and see where that landing point is as a distance from launch
[11:48] <SpeedEvil> (live stream)
[11:49] <edmoore> you need not record all the speeds on the way up in some sort of vector, you can just at each stage say 'if i were to drop now, where would i land' and the answer from , say, minute 0 to minute 1, might be '158m at a bearing of 38 degrees'
[11:49] <edmoore> then you save that
[11:51] <edmoore> then you say 'ok, it's minute 1, i am here' and at 2 minutes say 'now it's minute 2, i am here. winds are <blah>. if i were to drop from here to my altitude at 1 minute, how far away would i land' and the answer might be 256m away at a bearing of 45 degrees
[11:51] <edmoore> then you just add the minute 1-2 vector to the vector you got at minute 0 to minute 1
[11:52] <edmoore> and you save this new vector as the cumulative total so far
[11:52] <edmoore> then you start again from minute 2 to minute 3
[11:52] <edmoore> figure our where you would land if you fell from minute 3 altitude to minute 2 altitude
[11:52] <edmoore> add that vector onto your cumulative total
[11:53] <edmoore> and tada, you get this running tally of landing spot based on if you were to drop now
[11:53] <edmoore> infact steve has written this in C (ish) http://wiki.ukhas.org.uk/ideas:landing_spot_prediction
[11:54] <edmoore> we flew this on early novas
[11:55] <Laurenceb> theres a version I wrote in python as well
[11:55] <Laurenceb> with a "geofence" polygon
[11:57] <rjharrison> edmoore: cool That's is what I was nore or less thinking. I was going to take a vector from the launch site to the current position and assume that the way down is going to be roughly the same but smaller assuming descent rate > ascent rate.
[11:58] <SpeedEvil> Assume it's going to go for the edge of the polygon, with the highest speed observed so far. :)
[11:58] <rjharrison> Things change after burst on this model
[12:00] <edmoore> yeah that sounds cool.
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[12:36] Action: Laurenceb has discovered the joys of titanium alloy
[12:38] <SpeedEvil> aluminium-lithium
[12:38] <Laurenceb> heh
[12:38] <Laurenceb> its good for a ball joint for TVC
[12:38] <Laurenceb> low coefficient of friction and high shear strenght
[12:48] <Laurenceb> lower density than brass
[12:54] <SpeedEvil> coefficient of friction with what
[13:02] <Laurenceb> titanium alloy and alu alloy
[13:02] <Laurenceb> and titanium and titanium
[13:02] <Laurenceb> I was thinking of titanium for the inside of the joint
[13:03] <Laurenceb> and titanium cams for positioning
[13:03] <Laurenceb> about 4mm diameter eccentric cams
[13:05] <SpeedEvil> This is for what - the mounting for the combustion chamber?
[13:05] <SpeedEvil> so it gimbals as a whole?
[13:06] <Laurenceb> no. just the nozzle
[13:07] <Laurenceb> using a ~30 degree section of a ball joint
[13:07] <Laurenceb> if you see what I mean
[13:07] Nick change: kingj -> KingJ
[13:07] <SpeedEvil> yeah
[13:08] <SpeedEvil> don't you get massive heat gain into the exposed face?
[13:10] <Laurenceb> exposed face?
[13:11] <SpeedEvil> I'm missing the geometry you'reusing.
[13:12] Nick change: KingJ -> kingj
[13:12] Action: Laurenceb starts drawing a diagram
[13:16] Nick change: kingj -> KingJ
[13:16] <Laurenceb> http://imagebin.org/55419
[13:16] <Laurenceb> ok dead quick and dirty
[13:16] <Laurenceb> blue is insulating machiniable ceramic
[13:16] <Laurenceb> green aluminium
[13:16] <Laurenceb> yellow titanium alloy
[13:16] <Laurenceb> thats a cross section of one side
[13:17] <Laurenceb> the eccentric cam thingy should be perpendicular to the edge
[13:20] <SpeedEvil> where is this in relation to the throat
[13:20] <Laurenceb> edge of throat is to the right
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[14:31] <Laurenceb> are there peroxide safe greases?
[14:33] <SpeedEvil> I think silicone based should be moderately safe
[14:47] <Laurenceb> http://manuals.hobbico.com/fut/rs301cr-302cd-manual.pdf
[14:47] <Laurenceb> ^nice
[14:53] <Laurenceb> wonder how much you could increaser the voltage...
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[15:02] <RocketBoy> BBL
[15:02] <edmoore> jcoxon:
[15:03] <edmoore> off the top of your head, to you remember the URL with all the distributed listening stations on it?
[15:03] <edmoore> one of rjharrisons
[15:05] <SpeedEvil> google websdr
[15:05] <SpeedEvil> finds some
[15:05] <edmoore> that would be helpful if it was websdr that I had asked for
[15:06] <edmoore> it wasn't, so it's not.
[15:06] <edmoore> (sorry, just lost a presentation so am a bit fraught)
[15:07] <jcoxon> yup
[15:07] <jcoxon> one sec
[15:07] <SpeedEvil> sorry - i thought that was it.
[15:08] <jcoxon> http://maps.google.com/?q=http://www.robertharrison.org/listen/receivers.php&t=p
[15:08] <jcoxon> you mean that?
[15:08] <jcoxon> edmoore, ping
[15:08] <edmoore> bingo
[15:08] <edmoore> thanks jcoxon
[15:09] <jcoxon> 9np
[15:16] <Laurenceb> what does it take to run real time linux on my laptop?
[15:17] <jcoxon> don't you just need to patch the kernel
[15:17] <SpeedEvil> yes
[15:17] <SpeedEvil> there is probably a battery hit
[15:17] <SpeedEvil> why?
[15:17] <Laurenceb> so you can patch the kernel? nice
[15:18] <Laurenceb> was thinking of experimenting with it
[15:18] <jcoxon> Laurenceb, you might want to go VM to tell teh truth
[15:18] <jcoxon> will make your life easier in the long run
[15:18] <Laurenceb> virtual machine?
[15:18] <jcoxon> yes, for experimenting
[15:18] <jcoxon> even though it maynot be 'real' time
[15:18] <Laurenceb> ... how does that help?
[15:18] <Laurenceb> ah got you
[15:19] <jcoxon> it seperates everything
[15:19] <Laurenceb> yeah
[15:21] Nick change: edmoore -> edmoore|away
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[15:45] <Laurenceb> http://www.trossenrobotics.com/roboard.aspx?a=blog
[15:45] <Laurenceb> I want to run real time linux on that :P
[15:54] <Laurenceb> it has an FPU :D
[16:01] <Laurenceb> will the fpu be used if I compile with gcc?
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[16:15] <SpeedEvil> yes
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[20:07] <rjharrison> A quick MOSFET question if the ony switching is done by the avr do you need a capacitor in the circut? Ie the switched circuit is powered externally to the avr.
[20:09] <SpeedEvil> in what case?
[20:09] <SpeedEvil> you should probably have decoupling if that's what you're asking
[20:09] <rjharrison> Ok
[20:09] <rjharrison> I will
[20:10] <SpeedEvil> Also - a gate resistor is probably a good plan
[20:10] <SpeedEvil> For a number of reasons.
[20:12] <rjharrison> Humm Gate R what does that do other than lower the voltage ocomming from the AVR pin
[20:12] <SpeedEvil> Ok.
[20:12] <Hiena> Eh, are you plan to use an N type mosfet switching something?
[20:12] <rjharrison> Yep
[20:12] <SpeedEvil> Firstly - connect a capacitor directly to a IO, and when you change state, the current initially will be outside the datasheets absolute maximum ratings.
[20:12] <Hiena> Ok, first check the Ugs for the open.
[20:13] <SpeedEvil> This means that teh AVR is not actually specified to even work at all when you do that.
[20:13] <SpeedEvil> Secondly, you can get transients feeding back from the drain through the gate, and blowing the AVR
[20:14] <SpeedEvil> thirdly, you've got lots of gain in the transient state, and you can get massive oscillations if things go wrong
[20:14] <SpeedEvil> (lots of power gain, fairly little voltage gain)
[20:16] <rjharrison> Ok I need to have a bit of a read up on all this
[20:16] <SpeedEvil> I'm sure tehre is a fourth reason - but I've forgotten it.
[20:16] <Hiena> If it's in the IO voltage range of your uC that case you could connect simply to the output through a series 1k and paralell zener which is similar as your supply voltage, and a 100K resistor. The zener and the 100k should be connected between the gate and the source and the source connected to the gnd.
[20:17] <rjharrison> Vgs is about 1.5v iirc
[20:18] <rjharrison> I plan to switch cutdown using this mosfet
[20:18] <SpeedEvil> a 500 ohm resisstor in the gate will do fine then
[20:18] <Hiena> Ok. That will be workss.
[20:18] <SpeedEvil> and that's all you need
[20:19] <rjharrison> With a big cap to provide the initial power to the cutdown
[20:19] <rjharrison> Vcc avr = 3v
[20:19] <Hiena> Yeah. Due the cutdown resistor has low inductance, you could leave out the zener.
[20:19] <rjharrison> cudwon is pyro
[20:19] <rjharrison> cutdown
[20:19] <Hiena> The cap will be not enough.
[20:20] <rjharrison> but also low R
[20:20] <rjharrison> Uisinf 1amp elec match
[20:20] <SpeedEvil> how long does the pyro take to go?
[20:20] <SpeedEvil> You will need a quite large cap
[20:20] <rjharrison> 4700uF
[20:20] <rjharrison> 10V
[20:21] <SpeedEvil> that will provide 1A for 1/.047 of a second while discharging by 1V
[20:21] <Hiena> Go for the higher resistance for a pyro, an the thinnest wire which is aviable.
[20:21] <Hiena> You will have no enough current up there.
[20:21] <rjharrison> Works down here on the ground
[20:22] <rjharrison> Am I missing something
[20:22] <Hiena> For the low resistance you need current and that what is missing from the cold batteries.
[20:22] <Hiena> Remember when, you tries start an engine in cold condition.
[20:23] <RocketBoy> seen this?: http://wiki.ukhas.org.uk/ideas:flight_support
[20:23] <RocketBoy> bottom of the page
[20:23] <rjharrison> RocketBoy: BTW did you get the cheque?
[20:24] <RocketBoy> nope not yet
[20:24] <rjharrison> Humm
[20:24] <SpeedEvil> to see if it works with the cap alone - charge the cap through a 100R resistor from the bats
[20:24] <rjharrison> Should have been with you today
[20:24] <rjharrison> SpeedEvil: Ok will do
[20:25] <rjharrison> RocketBoy: White envelope A5 size
[20:25] <rjharrison> Hiena: Thanks for the help
[20:27] <RocketBoy> the igniters need circa 1A (into about 1.5 ohm) for 20ms
[20:27] <SpeedEvil> well - 20ms - the 4700uF cap should about do that
[20:28] <SpeedEvil> actually - what's the voltage?
[20:28] <RocketBoy> humm 1A x 1.5ohm = 1.5V
[20:28] <SpeedEvil> I mean - of your bats.
[20:28] <rjharrison> http://www.electricmatch.com/product_uk.html
[20:29] <rjharrison> Eithe 9v PP3 or 4xAA
[20:29] <RocketBoy> I use 3 x lithium AAs or AAAs - so at least 4.5V
[20:29] <SpeedEvil> 2 or 3 CR2016'sd be another option
[20:29] <SpeedEvil> The cap should be OK in that case.
[20:29] <SpeedEvil> I'd want at least 9V probably, to make fairly sure.
[20:30] <rjharrison> I'll do a quick test with a charged cap
[20:30] <rjharrison> give me a sec
[20:31] <RocketBoy> I used to use Davyfire ignitors - very reliable - but they arn't available to joe public any more
[20:34] <rjharrison> These are quite good http://www.electricmatch.com/product_uk.html
[20:34] <RocketBoy> all you seem to be able to get these days is Eastern European versions - no where near as good
[20:34] <rjharrison> Hum cap was not as quick as I thought. It took a second to fire
[20:36] <RocketBoy> they don't seem to spec a time to fire
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[21:52] <rjharrison> RocketBoy: With a 1xAAA it takes far less than a second to trigger
[21:55] <RocketBoy> sure - thats 1.5A according the spec - you shouldn't really notice much of a pause (if any) - but since they don't spec a fire time then you cant tell if its bad or good
[21:56] <RocketBoy> it sounds like it takes considerably more than a few tens of ms
[21:59] <RocketBoy> the daveyfire N28B (or N28BR) was actually 2ms at 1A - but those are "professional" igniters - fully speced.
[21:59] <RocketBoy> (yes 2ms)
[22:00] <SpeedEvil> also - they probably are not specced at -55C
[22:00] <SpeedEvil> I'd want to have a good second
[22:00] <SpeedEvil> Anyone want to buy 990 solar cells?
[22:00] <SpeedEvil> http://www.dmsolar.com/6mosoce.html
[22:00] <SpeedEvil> $1.5/W
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[00:00] --- Sat Jul 11 2009