[00:00] <Laurenceb> would coils actually work better?
[00:00] <shellevil> the loss is proportional (?) to torque
[00:00] <shellevil> but independant of speed
[00:00] <shellevil> so at high speeds, it's not actually that efficient
[00:01] <shellevil> as I understand it yes. however, my understanding on this is fuzzy
[00:01] <Laurenceb> yeah its all a bit odd
[00:01] <shellevil> s/that efficient/not that inefficient/
[00:30] <edmoore> youtube for 'spring missile'
[00:30] <edmoore> 100G
[00:35] <Laurenceb> strint
[00:35] <Laurenceb> yeah its pretty amazing
[00:35] <Laurenceb> *sprint
[00:38] <Laurenceb> http://www.youtube.com/watch?v=2aueAc7n6Qc&NR=1
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[00:46] <SpeedEvil> sunburn++
[00:47] <SpeedEvil> And supercavitating torpedos are just too fucking cool.
[00:48] <SpeedEvil> http://en.wikipedia.org/wiki/P-270_Moskit
[00:49] <SpeedEvil> 300Kg of mach-3 love.
[01:44] <Laurenceb> http://focus.ti.com/docs/prod/folders/print/cc1100.html#toolssoftware
[01:44] <Laurenceb> made for balloon use :P
[01:51] <shellevil> $?
[01:55] <Laurenceb> its in the etiny module
[01:55] <Laurenceb> not sure on price, hopefully $20 or something for a module
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[11:00] <jcoxon> morning all
[11:00] <SpeedEvil> morning
[11:01] <jcoxon> hey SpeedEvil how are those floor boards?
[11:01] <SpeedEvil> up at the moment, awaiting delivery of new
[11:01] <SpeedEvil> then I'll start insulating
[11:02] <jcoxon> cool
[11:04] <SpeedEvil> warm, hopefully :)
[11:10] <jcoxon> :-)
[11:12] <jcoxon> wow its just started to bucket it down
[11:12] <jcoxon> lucky i just reached the library
[11:12] <SpeedEvil> bright and sunny here.
[11:13] Action: SpeedEvil needs to move outside temperature sensor out of the sun.
[11:13] <SpeedEvil> It's not 23C :)
[11:13] <jcoxon> hehe
[11:20] <SpeedEvil> http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=120380628567&ssPageName=ADME:B:BOC:GB:1123 ...
[11:20] <SpeedEvil> 39 quid for a broken eeepc motherboard
[11:20] <SpeedEvil> with no RAM
[11:20] <SpeedEvil> that needs heatsinking
[11:21] <SpeedEvil> when screen-broken ones go for 60 quid with working m/b.
[11:21] Action: SpeedEvil doesn't understand some people.
[11:22] <jcoxon> hehe
[11:22] <jcoxon> got to love the rubbish on ebay
[11:22] <SpeedEvil> well - to be fair - I'm interested - but not at 39 quid
[11:23] <SpeedEvil> sensor fusion type thing for the car
[11:23] <SpeedEvil> 4 or so composite cameras -> composite->USB -> fusion -> VGA -> VGA-> composite adaptor -> 4.3" monitor
[11:24] Action: jcoxon is a fan of busted ibooks
[11:24] <SpeedEvil> Hmm. Diddn't realise the LHC is down till september
[11:25] <SpeedEvil> http://press.web.cern.ch/press/PressReleases/Releases2008/Images/PR17.08a_full.jpg Bendy!
[11:26] <jcoxon> yeah, they had to delay again
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[13:50] <mc-> jcoxon, I was reading http://spacenear.us/wiki/doku.php and the aims, and had a qn
[13:51] <mc-> why do you launch in the morning? isn't it better to launch late afternoon, so it doesn't lose helium until the next day?
[13:51] <jcoxon> hey mc-
[13:51] <jcoxon> yeah launch times are an interesting discussion
[13:52] <mc-> I thought spirit of knoxville launched in the evening?
[13:52] <jcoxon> in theory it is advantagous to launch at dusk
[13:53] <jcoxon> however logistically early morning launches are easier
[13:53] <jcoxon> and as we haven't done this before Mark Caviezel (the balloon maker) suggested go for a morning launch
[13:54] Action: SpeedEvil has silly thought
[13:54] <SpeedEvil> making the balloon ascend slowly and managing that with ballast
[13:55] <jcoxon> SpeedEvil: but we want ot be in the JS as soon as possible to throw us across the atlantic!
[13:55] <SpeedEvil> oh - right
[13:56] <jcoxon> :-)
[13:57] <jcoxon> mc-: later flights once we've got the launch sequence established could well be dusk to take advantage of the reduction in the loss of helium
[13:58] <mc-> why are early morning launches easier?
[13:58] <jcoxon> cause you are not racing against the oncoming darkeness
[13:59] <mc-> how about planning to launch at 1pm, and then end up launching at 5pm.
[14:00] <jcoxon> sounds like all our balloon launches :-D
[14:00] <SpeedEvil> don't want to sit with full balloon for ages
[14:00] <SpeedEvil> want to be able to see balloon inflating
[14:00] <mc-> get everything ready in the morning, and then inflate at 4.30pm, for a 5pm launch
[14:01] <jcoxon> mc-: the plan isn't set in stone so could well be changed, i think a carefully inflated balloon will conterbalance the additional helium lost with an earlier launch
[14:02] <mc-> is there a planned payload mass? and how much ballast is being carried?
[14:02] <jcoxon> there is a planned total mass
[14:02] <SpeedEvil> http://www.maplin.co.uk/Module.aspx?ModuleNo=1926
[14:02] <SpeedEvil> oops
[14:03] <mc-> I can help natrium with the globalstar satellite module
[14:03] <jcoxon> we'll adjust the ballast to make up the rest
[14:03] <jcoxon> though it'll be about <1kg payload + 4.5kg of ballast
[14:04] <jcoxon> the lighter the payload the more ballast we can carry, the longer the flight
[14:05] <jcoxon> mc-: i'm sure he'll appreciate the help
[14:05] <mc-> I think the ballast/payload ratio is important
[14:05] <jcoxon> it certainly is
[14:06] <jcoxon> but for a first flight we need a payload asap as we are running out of time to launch this season
[14:06] <mc-> I think a 10% reduction in payload gives a 50% reduction in ballast needed
[14:06] <SpeedEvil> it depends
[14:06] <SpeedEvil> oops
[14:06] <mc-> sorry I'm wrong
[14:06] <jcoxon> really? not sure i understand the logic
[14:07] <mc-> if the payload was reduced by 50%, then the ballast is reduced by 50%.
[14:08] <mc-> removing the globalstar module could reduce mass by 50%
[14:08] <SpeedEvil> mc-: I think you're assuming the balloon skin has zero mass
[14:09] <mc-> I think the skin mass is proportional to total mass?
[14:09] <jcoxon> okay but you've got to take into account the equilibrium we want to achieve between helium lift and paylaod mass
[14:09] <jcoxon> as we are aiming for a particular altitude
[14:13] <mc-> what do you think about having a small balloon to lift up the main balloon into the JS?
[14:14] <mc-> then the small balloon pops, leaving the main balloon to drift at JS altitude
[14:15] <jcoxon> it would work but practically it would be hard
[14:16] <mc-> with the 2 balloon method, I think the main balloon can be sealed, so it would leak very slowly.
[14:17] <jcoxon> where you've precalculated the required helium and payload mass to create a neutrally bouyant system?
[14:17] <mc-> yes
[14:18] <jcoxon> it would work, but its a lot more complicated then the traditional ZP approach
[14:18] <mc-> agreed, I'll try to not be too theoretical
[14:18] <jcoxon> its a similar idea to a superpressure balloon
[14:19] <jcoxon> (though not a super pressure :-D )
[14:19] <jcoxon> at*
[14:19] <mc-> superpressure is a lot harder
[14:21] <mc-> during the day it could be above the JS, and at night it falls into the JS, it could go for many days without ballast, so it might be simpler than a normal ZP.
[14:22] <jcoxon> only need 2 1/2 days :-)
[14:23] <mc-> 2.5 days in the JS though.
[14:23] <mc-> hard to keep it in the JS
[14:23] <jcoxon> http://spacenear.us/gfs/2009-03-10-0.png
[14:23] <jcoxon> ;:-D
[14:23] <jcoxon> thats actually a pretty rubbish example
[14:24] <jcoxon> i understand the concept though
[14:24] <jcoxon> for the next 3 launches we'll be sticking to the standard ZP system purely as we have 3 ZP balloons
[14:24] <jcoxon> and i think overall its a simple system
[14:24] <mc-> in your png, if you could launch off newfoundland it's only 2500 miles to Ireland.
[14:25] <jcoxon> its been shown to very nearly work
[14:25] <jcoxon> mc-: yeah it is but its also incredibly difficult for natrium to launch from at short notice
[14:26] <jcoxon> we decided instead to have the extra distance and be able to launch from his backyard
[14:26] <mc-> yes, understood. we need to find someone who lives in east coast canada, or boston.
[14:27] <jcoxon> it'll be fine
[14:27] <jcoxon> this would be a good day to fly: http://spacenear.us/gfs/2009-03-10-3.png
[14:28] <mc-> doesn't the JS often have a more northerly track?
[14:30] <jcoxon> not right now
[14:30] <jcoxon> the UK is using bearing the brunt of it
[14:34] <mc-> on the png, I can see it really slows down once it's below 10km
[14:35] <jcoxon> its a pretty impressive ribbon of air
[14:35] <jcoxon> either side is alot slower
[14:36] <mc-> can you change the sim to model what happens if you drop ballast earlier, so it stays above 10km for longer?
[14:36] <jcoxon> the sim doesn't take into account ballast
[14:36] <SpeedEvil> do you only get a 'cooked' png from the sim?
[14:36] <jcoxon> its actually just following a particle of air over three days
[14:36] <SpeedEvil> or do you get a list of times/dates/alts too?
[14:37] <SpeedEvil> I mean - how easy would it be to chain multiple sims
[14:37] <jcoxon> the model now runs on my laptop
[14:37] <jcoxon> i've automated it all
[14:38] <SpeedEvil> if under 10km, stop sim, note location, and restart 500m higher
[14:38] <SpeedEvil> till out of ballast
[14:39] <jcoxon> i could to that
[14:40] <jcoxon> though it doesn't take into account temperature
[14:44] <jcoxon> which is really going to effect our altitude
[14:45] <mc-> *affect
[14:46] <jcoxon> oops
[14:47] <mc-> out of interest, is the temperature more constant if the envelope is silvered?
[14:48] <mc-> Does a translucent balloon envelope heat up much?
[14:48] <jcoxon> not sure
[14:49] <jcoxon> laurence is the person to talk to about that
[14:51] <SpeedEvil> It's IR transparency that's moderately important
[14:51] <SpeedEvil> polythene is essentially transparent to longwave IR - heat
[14:52] <SpeedEvil> If you can have the top of the balloon reflecting, then that means you get heat from the earth/clouds below
[14:52] <SpeedEvil> even neglecting solar
[14:52] <SpeedEvil> and ~0C vs -55C is a moderate amount of heat
[15:02] <SpeedEvil> http://b3ta.com/board/9248785
[15:02] <SpeedEvil> relevant image is relevant.
[15:09] <jcoxon> hehe
[15:09] <jcoxon> but poor cat
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[16:44] <hallam> fergusnoble: about?
[16:45] <fergusnoble> yup
[16:45] <hallam> gimme a quick rundown on how to set up an svn repository?
[16:45] <hallam> on a linux server
[16:46] <hallam> the internet said scary things about hooks
[16:48] <fergusnoble> erm, its quite easy iirc
[16:48] <hallam> tried svnadmin create /var/svn/repos as root, which seemed to work, but then I get permission errors trying to write anything into the repository
[16:48] <fergusnoble> depends how you want to do it
[16:49] <hallam> it's so I can help Sondy with her matlab (her server)
[16:49] <fergusnoble> yeah, you need to give the svn folder the correct permissions
[16:49] <fergusnoble> you want to make the db file group writable or something
[16:50] <hallam> it's just a case of chmodding everything in /var/svn/repos?
[16:50] <hallam> should that be writable by, e.g. my account, or by the server account?
[16:52] <fergusnoble> by the account your logging in with if your using svn+ssh
[16:52] <fergusnoble> or are you using webdav?
[16:54] <hallam> svn+ssh I think
[16:54] <hallam> unless there's some compelling reason to use webdav
[16:57] <fergusnoble> webdav is better but harder to setup
[16:58] <fergusnoble> the reasons why its better probably dont apply to a small project
[16:58] <hallam> ok
[16:58] <hallam> this looks like it will work
[16:58] <hallam> thanks
[16:58] <fergusnoble> np
[16:58] <hallam> out of interest, why is webdav better?
[17:01] <fergusnoble> you get a web interface for free, much better user management (i.e. not done on the unix user level), and is more compatible with various clients
[17:02] <fergusnoble> but it involves being able to edit you apache config file
[17:02] <fergusnoble> basically it uses apache as the server through an apache plugin
[17:05] <hallam> ok
[17:05] <SpeedEvil> http://www.marvell.com/products/embedded_processors/developer/kirkwood/sheevaplug.jsp seems actually available
[17:05] <SpeedEvil> (fast USB+network computer in a leetle box for $99)
[17:05] <SpeedEvil> $30 shipping for one or two to the UK
[17:07] <SpeedEvil> But not at ~100 quid (if taxes are applied)
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[17:23] <jcoxon> afternoon all
[17:41] <jcoxon> ooooo amazing
[17:41] Action: jcoxon has got synergy to work on his 2 macs
[17:41] <jcoxon> one keyboard and mouse for 2 'puters
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[17:46] <hallam> synergy is so much fun, isn't it
[17:46] <hallam> hi simon
[17:49] <jcoxon> yeah especially as my old ibook has a dead keyboard and is right next to my macbook
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[18:13] <Laurenceb> hello
[18:13] <Laurenceb> I've finished the radio :P
[18:13] <hallam> hey Laurenceb
[18:13] <Laurenceb> discovered a few possible glitches which probably werent helping with the performance
[18:13] <hallam> (and natrium42 and Hiena )
[18:14] <Hiena> Hi all!
[18:14] <Laurenceb> it hibernates if theres no data and sends a "greeting" message every 10 seconds
[18:14] <Hiena> Got two 25 cm wide wings.
[18:14] <Hiena> FEw weeks, and my UAV will fly.
[18:14] <Laurenceb> awsome
[18:14] <hallam> nice
[18:14] <Laurenceb> what are you doing for guidance?
[18:14] <hallam> Laurenceb: this is the HF radio for transatlantic?
[18:15] <Laurenceb> hallam: mfsk for the mini rogallo
[18:15] <Hiena> Not to mention, it's fuselage made from xmass onament, Fanta bottle, and an advetisement board.
[18:15] <natrium42> hi
[18:15] <Laurenceb> lol
[18:15] <natrium42> hallam, how does launch opportunity look like?
[18:16] <Laurenceb> discovered something interesting about avr, reset only wipes the registers, not sram, so if you stick data in .noinit it will be retained in a reset
[18:16] <jcoxon> hey all
[18:17] <natrium42> Laurenceb, duh
[18:17] <Laurenceb> :P fairdoos
[18:17] <natrium42> Laurenceb, how do you think interrupt handlers retain memory
[18:17] <natrium42> :P
[18:18] <Laurenceb> they dont reset the uC
[18:18] <jcoxon> evening natrium42
[18:18] <Laurenceb> I dont see how thats similar
[18:18] <hallam> natrium42: still not great this p.m.
[18:19] <hallam> Laurenceb: ram isn't guaranteed to be zero on boot either, right?
[18:19] <natrium42> Laurenceb, reset is a kind of interrupt
[18:19] <Laurenceb> on power on I think it is
[18:20] <Laurenceb> natrium42: it just wipes the registers?
[18:20] <Laurenceb> interrupts allow you to cache the registers
[18:20] <natrium42> yeah
[18:21] <natrium42> there interrupt vector table contains reset as one of the entries
[18:21] <natrium42> hi jcoxon
[18:21] <Laurenceb> theres a neat trick you can do with the watchdog as well, it first behaves as an interrupt, then if you exit the ISR or fail to do so after some time delay it resets the uC
[18:22] <natrium42> hehe
[18:22] <hallam> usually reset's a bit more than an interrupt, but they definitely share some things
[18:22] <hallam> I'm surprised they guarantee sram is zero on startup though - I'm not familiar with avr, but that's unusual
[18:22] Action: Laurenceb has the entire datasheet printed off
[18:22] <Laurenceb> ... needs to read it
[18:23] <hallam> fergusnoble and I did a dirty hack on the torch
[18:23] <Laurenceb> torch?
[18:23] <hallam> for even dirtier reasons, we needed to temporarily store some information during power off
[18:23] <hallam> for up to a second or so
[18:23] <hallam> put it in a register that was "undefined" on reset, it held the data
[18:24] <hallam> think it was control register for the ADC or something
[18:24] <Laurenceb> ok
[18:24] <hallam> http://www.engadget.com/2005/11/03/angus-nobles-indium-smart-programmable-flashlight/
[18:24] <Laurenceb> whats the torch?
[18:24] <Laurenceb> oh that
[18:25] <Laurenceb> hehe is angus noble fergus's webstore?
[18:25] <hallam> him and his dad
[18:25] <Laurenceb> groovy
[18:25] <Laurenceb> but... a programmable torch
[18:26] <hallam> I know, I know
[18:26] <hallam> there's this weird subculture of torch geeks in america
[18:26] <Laurenceb> yeah we discussed this ages ago I domly recall
[18:26] <Laurenceb> ok... thats really saying something
[18:26] <Laurenceb> a whole new level of weird
[18:26] <hallam> willing to spend four digits on their torch collections
[18:27] <Laurenceb> ooh in that case...
[18:27] <Laurenceb> :P
[18:27] <hallam> I figure it's slightly less ridiculous than spending similar amounts on watches
[18:27] <jcoxon> oooo my silicone tubing should arrive tomorrow
[18:28] <SpeedEvil> candlepowerforums.com
[18:28] <SpeedEvil> For when you're looking for a torch that will fit in your pocket, and is absolutely guaranteed to be able to light stuff on fire.
[18:29] <hallam> http://en.wikipedia.org/wiki/Pendulum_Rocket_Fallacy I love the caption on the photo
[18:30] <SpeedEvil> :)
[18:32] <hallam> the last paragraph is dubious, though
[18:32] <Laurenceb> like the second photo
[18:32] <SpeedEvil> 'Given that torques are pseudo-vectors and hence add linearly, it follows that the rotation speed of the rocket around the aforementioned axis can only increase.'
[18:32] <SpeedEvil> Ah - clarity
[18:33] <hallam> ? that's clear enough, isn't it?
[18:33] <SpeedEvil> yes, if you understand all the terms.
[18:33] <hallam> hm, fair point
[18:33] <Laurenceb> I still dont see why the same rule doesnt apply to aircraft
[18:33] <SpeedEvil> I think it can be rewritten in much simpler languages.
[18:33] <Laurenceb> yes.. I'm stupid
[18:33] <hallam> which same rule?
[18:34] <SpeedEvil> Laurenceb: it does
[18:34] <hallam> and yeah, hence why you add weight to the nose of a paper aeroplane
[18:34] <Laurenceb> so how come polyhedral increases stability
[18:34] <SpeedEvil> cept those 'wing' things usually dominate
[18:34] <hallam> you mean dihedral?
[18:34] <Laurenceb> yeah
[18:35] <hallam> it works through a bunch of non-obvious side effects, but I don't see how it appears to contradict "forward CoG = more stable"
[18:36] <Laurenceb> hmm yeah I see
[18:36] <Laurenceb> sideslip
[18:36] <hallam> right
[18:36] <hallam> it only enhances roll stability
[18:36] <hallam> and the roll mode is usually so slow anyway that it's not that important if the pilot isn't a complete idiot
[18:37] <hallam> convenient in something unmanned though I guess
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[18:37] <Laurenceb> in the name of god the compassionate and merciful
[18:37] <Laurenceb> welcome edmoore
[18:43] <Laurenceb> :P
[18:43] <hallam> I think you scared him
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[18:52] <edmoore> ?
[18:52] <edmoore> 21 actual human people
[18:52] <edmoore> not bad
[18:53] <edmoore> ft bloody r. sigh
[18:53] <edmoore> everyone well?
[18:53] <Laurenceb> Im not human
[18:55] <edmoore> lol from cuspaceflight wiki
[18:55] <edmoore> fergusnoble: did you mean to write this?
[18:55] <edmoore> 'Please try and follow SVN etiquette i.e. only commit code that you have broken'
[18:59] <hallam> hahaha
[19:03] mc- (n=mfcastle@cpc3-glfd1-0-0-cust439.glfd.cable.ntl.com) left irc:
[19:04] <gordonjcp> lol
[19:07] <fergusnoble> edmoore: oops
[19:07] <edmoore> :p
[19:07] <edmoore> probably more accurate than the alternative
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[19:50] <edmoore> fergusnoble: rescued jtag from dpo
[19:50] <fergusnoble> and my eee charger?
[19:50] <edmoore> yep
[19:50] <edmoore> both in bag
[19:50] <edmoore> bbl
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[20:00] <jcoxon> hey RocketBoy
[20:02] <RocketBoy> hey jcoxon - how is the ballast sub-system going
[20:02] <jcoxon> hey
[20:02] <jcoxon> ummm i've got the valves - just waiting for some tubing to be delivered
[20:02] <jcoxon> a little worried the vavles are a bit small
[20:03] <RocketBoy> are you working with a pressurised container?
[20:03] <jcoxon> the plan wasn't to have one
[20:04] <jcoxon> but am going to do some testing
[20:04] <jcoxon> do you think it should be pressurised?
[20:05] <RocketBoy> difficult to say without some investigation - I would have thought so.
[20:05] <RocketBoy> somthing like a fizzy drink bottle with some air in it at release
[20:06] <RocketBoy> then at altitude it would offer a bit of pressure
[20:07] <jcoxon> hmm the valve i've got is only rated to 6psi
[20:09] <jcoxon> oh well we shall have to see
[20:09] <RocketBoy> thats not much - you would have to take that into accountwhen sealing the bottle - just allow some space for gas expansion - so that it was never more than 6psi
[20:09] <hallam> http://www.youtube.com/watch?gl=GB&hl=en-GB&v=RecckjgLyqo
[20:10] <jcoxon> RocketBoy, would we then not need a check valve to let air back in?
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[20:13] <jcoxon> i guess not, the expanding air would continue to force out the liquid which is what we want
[20:13] <RocketBoy> no I don't think so - put enough air in it so that there is always some positive pressure until all the fluid is used up
[20:14] <jcoxon> okay well once i get the tubing i'll rig a system up
[20:14] <jcoxon> and then i'll take it up to cam and borrow the atmos chem departments vacuum chamber
[20:14] <jcoxon> hows the radio coming along?
[20:15] <RocketBoy> OK - still doing the PIC at the mo
[20:15] <RocketBoy> soldering as we speak
[20:16] <jcoxon> excellent
[20:17] <jcoxon> mc- has some rockmites if the ordered one takes too long
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[20:20] <RocketBoy> Ah ok - thats a good backup - although its not holding me up at the mo
[20:20] <jcoxon> fair enough
[20:20] <jcoxon> well i'm all set for testing :-)
[20:21] <jcoxon> my wire antenna is a lot better then my first few attempts
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[20:23] <jcoxon> hmm perhaps a check valve that has an operating positive pressure of over 6psi
[20:27] <jcoxon> wow gsm modules have become cheap
[20:27] <jcoxon> http://uk.farnell.com/jsp/search/productListing.jsp?ICID=i-f4bf-00002947&SKUS=1678274,1678282,1678283,1678285,1678286,1678288,1678289,1678290,1678291,1678293,1678294,1678295,1678296,1678297,1678298,1678299,1678300,1678301,1678302
[20:27] <hallam> that might be important if you get low
[20:29] <RocketBoy> I just applied for a farnell trade account - if you ever want anything without paying a minimum charge (assuming I get it)
[20:29] <hallam> they seem to have stopped doing the minimum charge thing
[20:29] <hallam> free shipping, no minimum order
[20:31] <RocketBoy> humm - why am I applying for an account then
[20:31] <RocketBoy> they seem to advertise free shipping and no minimum order for trade accounts
[20:32] <RocketBoy> on their site
[20:32] <hallam> hm
[20:32] <hallam> maybe they decided I'm worthy of it? anyone else checked?
[20:32] <jcoxon> i don't remember their being a minimum order
[20:33] <jcoxon> ooo found a non-return valve that operates at 0.3bar
[20:33] <RocketBoy> well no mimimum order but a shipping charge
[20:33] <hallam> http://uk.farnell.com/jsp/bespoke/bespoke4.jsp?bespokepage=farnell/en_UK/support/order.jsp#delivery
[20:34] <RocketBoy> 0.3 bar = about 5psi - thats worse
[20:34] <hallam> I actually ordered some stuff last night at 7pm and it was here this morning, was quite impressed
[20:36] <jcoxon> if the valves work below 6psi then we surely want to keep the pressure under that
[20:36] <jcoxon> and so if the check valve opens at 5psi then it'll remain in the right range
[20:38] <hallam> where does the check valve go? (and in which direction?)
[20:39] <jcoxon> hmmm good point
[20:40] <jcoxon> have i got my thinking the wrong way round?
[20:41] <hallam> I'm not sure, I'm just confused :P
[20:41] <hallam> ok think about the objectives
[20:42] <jcoxon> so we have a resevoir with both liquid and a bit of air
[20:42] <hallam> you want the tank pressure to be high enough that the ballast valve operates reliably, and that it comes out at a reasonable speed
[20:42] <jcoxon> yes
[20:42] <hallam> but not so high that it explodes?
[20:42] <hallam> or is there some other reason for it not to be too high
[20:42] <jcoxon> yeah cause its a normally closed valve
[20:42] <hallam> so is the maximum pressure limit because of the valve or because of the tank?
[20:43] <jcoxon> ooo wait one sec
[20:43] <jcoxon> i've miss read the datasheet i think
[20:43] <hallam> I'd be a bit surprised it the max pressure limit of the valve was less than at least a bar or two
[20:43] <hallam> if*
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[20:44] <jcoxon> i can't seem to find a max pressure
[20:44] <jcoxon> i think the 6psi i'm seeing is for a minimum flowrate
[20:45] <SpeedEvil> The valve may well not open at higher pressure
[20:45] <SpeedEvil> or not close
[20:45] <jcoxon> so to get a reasonable flow rate we are going to need about 6psi
[20:45] <hallam> yeah but I'd have thought that would have to be pretty high, higher than is probably relevant here -- but that is only a hunch
[20:45] <SpeedEvil> you thinking of pressuring the bottle?
[20:45] <hallam> yes
[20:46] <SpeedEvil> Is there a need?
[20:46] <SpeedEvil> does it really matter if the valve is open for a total of half an hour?
[20:46] <hallam> jcoxon: you might not need what they call a reasonable flow rate
[20:46] <jcoxon> true
[20:46] <jcoxon> but we want a flow rate
[20:47] <SpeedEvil> (my experiments with a 10cm head and a 1mm apature indcated ~1g/s flow for alcohol
[20:47] <jcoxon> okay so perhaps we don't need anything apart from a tank (bottle), tube and the valve
[20:47] <hallam> yeah I guess you may not need it to be fast but you do need it to be repeatable
[20:47] <SpeedEvil> how high is the payload?
[20:48] <jcoxon> we leave a bit of air to expand and provide the pressure
[20:48] <SpeedEvil> Is there a reason the bottle couldn't be - say - 30cm over the payload?
[20:48] <hallam> good idea
[20:48] <jcoxon> hallam, tis RocketBoy's idea
[20:48] <hallam> SpeedEvil's hydrostatic idea is good too
[20:48] <jcoxon> my original mistake was that 6psi was the pressure where the valve failed
[20:49] <RocketBoy> farnell say "If you are a Trade account customer we offer free next working day delivery on all orders placed before 8pm"
[20:49] <hallam> heh
[20:49] <RocketBoy> so next day delivery is the only advantage
[20:50] <jcoxon> SpeedEvil, walk me through your idea
[20:50] <jcoxon> i'm not sure i've worked it out
[20:50] <hallam> well the non-trade also seems to be next day
[20:50] <SpeedEvil> jcoxon: simple
[20:50] <RocketBoy> yeah
[20:50] <hallam> jcoxon: you have the tank some distance above the valve
[20:50] <hallam> gravity gives you free hydrostatic pressure head
[20:50] <SpeedEvil> jcoxon: 3l coke-bottle full of alcohol 30cm over the payload
[20:50] <SpeedEvil> jcoxon: pipe down to the bottom of the payload where the valve is
[20:50] <hallam> spray payload with alcohol, light match - instant cutdown!
[20:50] <SpeedEvil> jcoxon: maybe 40-60cm total head over the valve
[20:51] <hallam> 1m = 0.1 bar
[20:51] <SpeedEvil> rapidly you get into diminishing returns.
[20:51] <hallam> friction and all that
[20:52] <jcoxon> hmmm i guess the tank could be above
[20:52] <jcoxon> snox had it below
[20:53] <jcoxon> which i think made it easy to work with
[20:53] <hallam> it can still be below, you just have the valve even lower
[20:53] <jcoxon> how much of an advantage will it bring?
[20:54] <SpeedEvil> I don't think it's really much required
[20:54] <hallam> just enough to give you a bit of a flow rate
[20:54] <hallam> do you have the valve?
[20:54] <jcoxon> yes
[20:54] <hallam> then it should be pretty easy to test the flow rate
[20:54] <SpeedEvil> you open the valve for a minute, and see if the level drops far enough
[20:54] <jcoxon> but no suitable tubing (arrives tomorrow)
[20:54] <hallam> ok
[20:54] <jcoxon> the further the valve from the payload the hard to insulate...
[20:55] <hallam> true
[20:55] <jcoxon> and nothing is really rated that low
[20:55] <jcoxon> on a side note :-D http://www.gizmoforyou.com/shop/index.php?main_page=product_info&cPath=3_39&products_id=61&zenid=1da241622cdc4cac3407346f95d0a8a1
[20:55] <jcoxon> they made my request
[20:55] <hallam> offtopic - Saturn's really obvious just 6 degrees up and left of the moon right now
[20:55] Action: SpeedEvil passes jcoxon a straw and some blutak
[20:55] Action: SpeedEvil looks into his tubing box.
[20:56] <jcoxon> these valve are ridiculously tiny
[20:57] <jcoxon> stupidly tiny
[20:57] Action: SpeedEvil passes jcoxon a really high-flow low-pressure valve.
[20:57] <jcoxon> http://spacenear.us/wiki/doku.php?id=ballast:valve
[20:57] Action: SpeedEvil puts away the other bath-tap.
[20:57] <hallam> wow that's a cool idea (gizmoforyou)
[20:57] <jcoxon> yeah
[20:57] <hallam> that is quite small
[20:57] <hallam> what's the orifice diameter?
[20:58] <SpeedEvil> 1.2mm IIRC
[20:58] <SpeedEvil> if it's the 6psi valve
[20:58] <jcoxon> 1.143mm
[20:58] <jcoxon> and takes 1/16" ID tubing
[20:59] <SpeedEvil> you can take a straw, and pull it gently over a lighter to stretch it out.
[20:59] <hallam> low viscosity is definitely going to be your friend
[20:59] <hallam> methanol should be okay
[21:00] <hallam> http://www.bunniestudios.com/blog/?p=284 I wonder if gizmoforyou is one of these guys
[21:00] <SpeedEvil> liquid helium.
[21:00] <jcoxon> SpeedEvil, we could vapourise it into the balloon :-)
[21:01] <SpeedEvil> Liquid hydrogen + catalyst for heating
[21:01] <SpeedEvil> I think I already suggested tritium.
[21:01] <jcoxon> i guess i better purchase that breakout board as i did suggest it to them
[21:01] <SpeedEvil> :)
[21:02] <RocketBoy> does anyone to a 0.05" matix board?
[21:03] <SpeedEvil> I vaguely remember seeing it
[21:03] <SpeedEvil> actually
[21:03] <SpeedEvil> I think I've got some in a box near here
[21:03] <SpeedEvil> I've no idea where I got it
[21:03] <SpeedEvil> actually, I think it was from a liquidation of RoDime.
[21:03] <SpeedEvil> Which isn't likely to help you
[21:05] <RocketBoy> it seems like a logical thing to be available - but I havn't found any at a sensible price
[21:05] <SpeedEvil> There is always the silly solution.
[21:05] <hallam> Sparkfun do various SMT prototyping boards, at non-sensible prices
[21:05] <SpeedEvil> pcbpool.com
[21:05] <RocketBoy> I'm sort of tempted to knock some up in eagle
[21:06] <SpeedEvil> I came up with an interesting idea, that I'm not sure how practical it is
[21:06] <SpeedEvil> take normal veroboard
[21:06] <SpeedEvil> now, in between each hole place a hole in the copper, and narrow the track round it
[21:06] <SpeedEvil> to guide a spot face cutter
[21:07] <SpeedEvil> and on the opposite side of the plated-through-hole board, put tracks going at right angles
[21:07] <SpeedEvil> The silly version of this has a ground plane in the middle
[21:08] <hallam> how do you get to the ground plane?
[21:08] <hallam> occasional access holes?
[21:08] <SpeedEvil> something like that
[21:09] <SpeedEvil> I think it may be overkill - though in principle it's more flexible, without actual CAD, it's going to be harder to layout
[21:09] <SpeedEvil> Though with CAD, it could be very flexible, and really fast - you'd need a very simple machine to break the links
[21:10] <hallam> I've used CAD for moderately complex veroboard layouts before
[21:10] <hallam> SpeedEvil: done much wire wrap?
[21:11] <SpeedEvil> hallam: not much
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[21:11] <hallam> me neither, but it can be pretty powerful
[21:11] <SpeedEvil> I think I did an EPROM programmer, and that was it.
[21:11] <hallam> hi jatkins
[21:12] <jatkins> hi
[21:12] <hallam> I tried to fix an ex-Los Alamos neutron counter
[21:12] <hallam> to no avail
[21:15] <hallam> If you ever wanted to see someone be completely and utterly ripped apart by a bunch of vengeful radio engineers: http://fjallfoss.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6520196917
[21:15] <hallam> it's painful
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[21:36] <natrium42> radio engineering is serious business :(
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[21:37] <jatkins> jcoxon: I've got the radio sort of working
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[21:39] <jcoxon> hey jatkins
[21:39] <jcoxon> sort of?
[21:40] <jatkins> I've got it receiving
[21:40] <jatkins> but not the computer decoding
[21:41] <jatkins> so it's making a tone when the arduino + ntx2 are turned on
[21:41] <jatkins> completely different to the static
[21:41] <jcoxon> great
[21:41] <jcoxon> and if you toggle the tx line does it go on and off?
[21:42] <jcoxon> remember there are 2 pins, the EN line turns the module on and then the TX line does the tones
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[21:42] <jatkins> well if I unplug the arduino usb cable (which powers i) it goes off
[21:42] <jatkins> i'll have a go unplugging the tx line
[21:42] <jatkins> yeah, it stops when i unplug the tx line
[21:43] <jcoxon> so you could make morse code by turning hte tx line on and off
[21:43] <jatkins> yeah
[21:43] <jatkins> I've uploaded the code you put on your wiki
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[21:43] <jatkins> http://www.pegasushabproject.org.uk/wiki/doku.php/ideas:notes
[21:43] <jatkins> there ^
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[21:44] <jcoxon> okay and do you have 2 resistors
[21:44] <jatkins> oops
[21:44] <jatkins> forgot..i'll put them on now
[21:44] <jatkins> 22K on the EN line?
[21:44] <jcoxon> no
[21:44] <jatkins> 2k2?
[21:44] <jcoxon> no
[21:45] <jcoxon> so the EN line should be directly attached to the arduino
[21:45] <jcoxon> this will turn the radio on and off
[21:45] <jatkins> oh
[21:45] <jatkins> i had one gpio going to the EN line, the other going to txd
[21:45] <jcoxon> have one gpio going to the EN line
[21:45] <jatkins> En line should go to a high gpio all the time?
[21:46] <jcoxon> pretty much yes
[21:46] <jatkins> ok
[21:46] <jatkins> with a resistor?
[21:46] <jcoxon> no
[21:46] <jatkins> ok
[21:46] <jcoxon> now for rtty you want 2 tones
[21:46] <jcoxon> so 2 frequencies
[21:46] <jatkins> so i have gpios 9 and 11 with resistors on each?
[21:46] <jatkins> yeah
[21:46] <jcoxon> and the radiometrix decides it freq by teh voltage on the TX line
[21:47] <jatkins> ok
[21:47] <jcoxon> so we cheat a little
[21:47] <jcoxon> and have 2 gpios going to the TX line
[21:47] <jcoxon> when one is high the other is low
[21:47] <jatkins> oh ok
[21:47] <jcoxon> and vice versa
[21:47] <jcoxon> and the resistors go on the lines to vary teh voltage a little
[21:47] <jatkins> just one gnd for both gpios? as they both go to the same line?
[21:47] <jcoxon> to get our 2 different freqs
[21:47] <jatkins> yeah
[21:48] <jcoxon> one sec i'll draw it
[21:48] <jatkins> thx
[21:49] <jcoxon> http://www.pegasushabproject.org.uk/wiki/doku.php/ideas:notes
[21:49] <jcoxon> back in 5mins
[21:49] <jatkins> thx
[21:54] <jcoxon> does that makes senese?
[21:54] <jcoxon> sense*
[21:55] <jatkins> yeah
[21:56] <jcoxon> i've added a few more lines
[21:56] <jcoxon> bbiab
[21:57] <jatkins> ok
[21:57] <jatkins> I thought VCC was 3.3V?
[22:03] <jcoxon> oh yeah good point
[22:03] <jcoxon> check the datasheet
[22:03] <jcoxon> i can't remember
[22:05] <jatkins> yeah, it is
[22:05] <jatkins> well ~3
[22:05] <jatkins> I've connected it all up
[22:05] <jatkins> it's producing a high pitch tone
[22:05] <jatkins> and then just static when i disconnect the power to the ntx2
[22:10] <jcoxon> okay and did you load the code up?
[22:11] <jatkins> yeah
[22:11] <jcoxon> okay and what does the serial say?
[22:12] <jatkins> the serial? on the arduino?
[22:12] <jcoxon> yeah
[22:12] <jatkins> the serial output?
[22:12] <jcoxon> yeah
[22:13] <jatkins> what baud is it?
[22:13] <jcoxon> 9600
[22:13] <jatkins> yeah it's saying "TEST"
[22:13] <jcoxon> okay and the radio
[22:14] <jcoxon> what can you hear?
[22:14] <jcoxon> tune up and down
[22:14] <jatkins> really high pitched bleeping
[22:14] <jatkins> really fast
[22:14] <jcoxon> 2 tones?
[22:14] <jatkins> should it be changing?
[22:15] <jatkins> it's just bleeping
[22:15] <jatkins> actually yeah, two tones
[22:15] <jatkins> it's alternating between the bleeping and then a long tone
[22:16] <jatkins> so alternating between high pitch bleeping and a long quieter tone
[22:16] <jatkins> i guess like morse code sort of
[22:16] <jcoxon> quicker
[22:16] <jcoxon> i'll try and find an example
[22:16] <jatkins> yeah
[22:16] <jcoxon> acutally there is a wav on wikipedia
[22:17] <jatkins> on the rtty article?
[22:17] <jcoxon> yeah
[22:17] <jatkins> found it
[22:19] <jatkins> yeah pretty much the same tones
[22:20] <jatkins> basically exactly the same]
[22:22] <jcoxon> great
[22:22] <jcoxon> thats rtty
[22:22] <jcoxon> now you need to get a cable to plug it into your laptop and you can decode it
[22:22] <jatkins> yeah
[22:22] <jatkins> i've downloaded fldigi
[22:23] <jcoxon> do you have a cable
[22:23] <jatkins> i'm not sure
[22:23] <jatkins> is it a barrel plug audio cable?
[22:23] <jcoxon> if not you could cheat a little and use the mic on the laptop near to the speaker
[22:23] <jcoxon> yeah
[22:23] <jcoxon> but the mic/speaker is crap
[22:23] <jatkins> ah
[22:24] <jatkins> i have an external mic
[22:24] <jcoxon> the barrel cable direct will be best
[22:24] <jatkins> ok
[22:24] <jatkins> i'll have a look for one and buy one if i need to
[22:24] <jcoxon> but for testing you could try fldigi using the latop's mic
[22:24] <jatkins> ok
[22:24] <jatkins> i've g2g now
[22:24] <jcoxon> np
[22:24] <jcoxon> good work on getting it working
[22:24] <jatkins> thx for the help
[22:24] <jcoxon> np
[22:24] <jatkins> cya
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[22:25] <natrium42> hey jcoxon, how is mentorship going? :)
[22:26] <jcoxon> hehe
[22:26] <natrium42> i got the 25 old-version gps chips
[22:26] <jcoxon> well he got it working
[22:26] <jcoxon> great
[22:26] <natrium42> going to solder a few units
[22:26] <jcoxon> cool
[22:26] <natrium42> need to get RF section working :S
[22:28] <natrium42> sYx66, did you hear back from the government yet?
[22:29] <natrium42> jcoxon->setNagMode(sYx66, PERIODICAL);
[22:29] <jcoxon> okay
[22:29] <natrium42> :D
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[22:32] <natrium42> sts launch tomorrow
[22:39] <SpeedEvil> has the planet detector sat actually opened?
[22:39] <SpeedEvil> and started reporting?
[22:41] <jcoxon> ooo what time?
[22:42] <natrium42> 9:20 EDT
[22:42] <natrium42> pm
[22:42] <natrium42> so late at night for you
[22:42] <SpeedEvil> what's EDT?
[22:42] <SpeedEvil> -5?
[22:43] <natrium42> yeah
[22:44] <jcoxon> ouc
[22:53] <jcoxon> ouch*
[23:01] <jcoxon> natrium42, the tubing should arrive tomorrow
[23:01] <jcoxon> so i'll rig up something tomorrow hopefully
[23:02] <natrium42> ok, excellent
[23:07] <SpeedEvil> ika: there are 2MP webcams
[23:07] <SpeedEvil> oops
[23:08] <natrium42> they still have a tiny sensor and quality is awful
[23:08] <natrium42> :P
[23:09] <SpeedEvil> actually - the creative one I have is 'ok'
[23:09] <SpeedEvil> better than I'd have expected
[23:10] <SpeedEvil> Here, I'd give you a sample of video, but I've forgotten which of eleventy fucking billion boxes it might be in
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[23:13] <SpeedEvil> My actual only real annoyance with it is it's rolling shutter
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[00:00] --- Wed Mar 11 2009