highaltitude.log.20090223

[00:00] <hallam> my camera can run at 30fps, I'm not really expecting to be able to identify position from no prior knowledge at a 30Hz rate
[00:00] <hallam> but there's no need to do that
[00:01] <hallam> because as soon as you have identified it once, you can go to tracking
[00:01] <Laurenceb> yeah, but I guess the stars will disappear into the noise?
[00:01] <hallam> depends, for tracking you only need 2 stars, so you have a higher chance of getting 2 bright ones in a given frame than if you needed 10 or whatever
[00:02] <hallam> from the very limited testing we did today, I think the limiting magnitude at a 30Hz exposure rate is probably around 1 or 2 with my sensor and lens
[00:02] <hallam> it's not a very good sensor, I might upgrade it
[00:03] <hallam> in the end it all boils down to a limitation on the fastest slew rate that you can track at
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[00:11] <shellevil> The above sensor looks interesting - the one I posted - a bit expensive though.
[00:11] <shellevil> I wonder if B grades are still available.
[00:11] <shellevil> hall: FOV?
[00:12] <shellevil> hallam: xephem has a little program with it that will dump all the stars over magnitude x in a FOV pointed x,y at time z
[00:13] <shellevil> I've used it for star tracker stuff in the past.
[00:14] <shellevil> one problem is spin control - if you've not got it, you can have problems.
[00:14] <shellevil> My previous star tracker - still got prototype bits - was based on a CCD - exview - HAD - very good response down into the IR - on a little gimbal.
[00:27] <hallam> shellevil: 14x11 deg FOV
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[00:55] <SpeedEvil> ah
[00:55] <SpeedEvil> From memory, you need to hit magnitude 4 or 5 in order to get reliable data.
[00:56] <SpeedEvil> Otherwise there are _lots_ of 'holes'.
[00:56] <SpeedEvil> maybe even 6
[00:56] <SpeedEvil> reliable - >3 stars or so in view at all times.
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[05:36] <natrium42> hi
[05:39] <sYx66> hi
[05:39] <natrium42> the balloons are ready :)
[05:39] <natrium42> mark even added an option to use hydrogen instead of helium
[05:42] <natrium42> the membrane is less permeable to hydrogen & hydrogen is cheaper
[05:42] <natrium42> it's worth considering
[06:17] <sYx66> hybrid? :D
[06:30] <natrium42> lol
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[07:11] <jcoxon> where is natrium when you need him :-p
[07:19] <sYx66> probably working away at something
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[07:21] <jcoxon> need to sort out a name for the trans-atlantic attempt
[07:21] <jcoxon> oh well it can wait
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[07:29] <sYx66> natrium... what's our mission going to be called?
[07:29] <sYx66> i like HALO
[07:30] <jcoxon> HALO has been used before though
[07:31] <jcoxon> both natrium's old flights and also the rockoon they launched a few years ago i think
[07:31] <sYx66> yeah but it can be HALO3 or HALO Atlantic
[07:32] <jcoxon> true
[07:32] <jcoxon> hopefully i'll get some details of these valves today
[07:32] <sYx66> are you doing liquid ballast?
[07:32] <jcoxon> yeah
[07:32] <jcoxon> denatured ethanol
[07:33] <sYx66> isn't liquid too pricise?
[07:33] <jcoxon> laurence though is having problems with the level sensor he developed for it
[07:33] <jcoxon> the release mechanism is relatively easy though
[07:33] <sYx66> some rough estimates show that each drop will be fairly heavy.
[07:34] <jcoxon> with solid ballast either you are having multiple 'cutdowns' which might fail
[07:34] <jcoxon> or a complicated release mech
[07:34] <jcoxon> sYx66, yeah but over a relatively long time
[07:34] <jcoxon> we arent' in too much hurry to dump our ballast
[07:34] <jcoxon> if it takes 30mins then it takes 30 mins
[07:34] <jcoxon> and also allows the negative feedback system to work
[07:35] <sYx66> well you'll be going up and down in the wind... so it will have to decide every X unit of time to drop... like every hour.
[07:35] <sYx66> to filter out the noise
[07:35] <jcoxon> sure
[07:35] <sYx66> at that point you want to be able to drop a set amount fast to recover.
[07:36] <sYx66> i'm just playing devil's advocate :)
[07:37] <sYx66> also with solid ballast you just have independent relays controlling cut off, so you have backup. with a valve you have a single point of failure
[07:37] <sYx66> which is more mechanically complex
[07:43] <jcoxon> :-)
[07:43] <jcoxon> looking at past attempts - liquid has been very sucessful
[07:44] <jcoxon> and the preciseness could be important
[07:44] <jcoxon> right just running latest forecasts
[07:46] <jcoxon> http://spacenear.us/gfs/
[07:47] <jcoxon> hmmm interesting - still a great window 24/25
[07:47] <jcoxon> but also 1st march potentially
[07:48] <jcoxon> oh well - wea aren't anywhere near ready :-)
[07:57] <jcoxon> bbl
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[08:18] <natrium42> hi edmoore
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[08:19] <natrium42> ...
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[09:20] <Laurenceb> hello
[09:28] <Laurenceb> anyone up for a launch soon?
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[16:31] <jcoxon> afternoon all
[16:49] <SpeedEvil> 'noon
[16:54] <jcoxon> hey SpeedEvil
[16:58] Action: SpeedEvil found a billion balloons in the cupboard.
[16:58] <SpeedEvil> 3M samples ++
[16:58] <SpeedEvil> (glass microballoons)
[16:59] <SpeedEvil> They look just like little soap bubbles under the microscope.
[17:08] <Laurenceb> what for?
[17:09] <SpeedEvil> I got them to play with for making rocket bits.
[17:09] <SpeedEvil> Epoxy + glass balloon + carbon fibre mixed is a _really_ light composite.
[17:09] <SpeedEvil> http://solutions.3m.com/wps/portal/3M/en_US/Energy-Advanced/Materials/Product_Info/Prod_Catalog-SMD/?PC_7_RJH9U5230GE3E02LECFTDQ4G06_nid=M9MDXCG178beWHB23F5LMRgl
[17:11] <Laurenceb> ok yeah I've used them with epoxy
[17:14] <Laurenceb> doesnt it weaked then epoxy?
[17:16] <SpeedEvil> It's a lot stiffer, but weaker, yes.
[17:20] <SpeedEvil> It's also a hell of a lot lighter
[17:20] <SpeedEvil> so for a given part weight, you get much, much greater stiffness if you put balloons in (typically)
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[17:30] <Laurenceb> hi jatkins
[17:30] <jatkins> hi
[17:31] <Laurenceb> hows life?
[17:31] <jatkins> cool
[17:31] <jatkins> you?
[17:33] <Laurenceb> yeah not so bad... hopefully launching soon
[17:34] <jatkins> cool
[17:34] <Laurenceb> need some good weather and ideally someone else launching at the same time
[17:34] <jatkins> the glider?
[17:34] <Laurenceb> also some means of transport
[17:34] <Laurenceb> yeah
[17:34] <jatkins> cool
[17:34] <jatkins> is it a low altitude test?
[17:34] <Laurenceb> probably get a large fthin box from homebase and use the train
[17:34] <Laurenceb> 10Km
[17:34] <jatkins> cool
[17:35] <jatkins> so is rogallo easier than fixed wing?
[17:35] <Laurenceb> yeah pretty much
[17:35] <Laurenceb> fairly easy to control
[17:35] <jatkins> just normal control surfaces?
[17:35] <Laurenceb> but I want to work on fixed wing in future
[17:36] <Laurenceb> no, C of G shift
[17:36] <jatkins> what's that ?
[17:36] <Laurenceb> center of gravity
[17:36] <jatkins> oh yeah
[17:36] <jatkins> so just tilt it?
[17:37] <jatkins> with a servo?
[17:37] <Laurenceb> basically you tilt the wings relative to the body
[17:37] <Laurenceb> yeah
[17:37] <jatkins> can you do roll, pitch and yaw just with wings?
[17:37] <Laurenceb> I only pitch them
[17:37] <jatkins> ok
[17:37] <Laurenceb> erm roll even
[17:37] <jatkins> yeah
[17:38] <jatkins> do you use weights for pitch?
[17:38] <jatkins> i think someone said that on here ages ago
[17:38] <Laurenceb> you setup the body so it glides well
[17:39] <Laurenceb> rather hard to do in practice
[17:39] <Laurenceb> I used lots of tests
[17:39] <jatkins> yeah
[17:39] <jatkins> I think I saw one of the vids
[17:39] <jatkins> pretty cool
[17:39] <jatkins> can it land in a designated location (ie launch site) or is it just for gliding?
[17:40] <Laurenceb> yeah you can enter in a landing location
[17:40] <jatkins> cool
[17:40] <jatkins> lon / lat?
[17:40] <Laurenceb> yep
[17:40] <jatkins> neat
[17:40] <jatkins> is the autopilot just gps + compass module + flight comp?
[17:40] <jatkins> + imu
[17:40] <Laurenceb> gps+microcontroller+rate gyro
[17:40] <shellevil> He's got GPS and gyro just I think
[17:41] <jatkins> neat
[17:41] <shellevil> and dominoex link back to the ground, with R/C terminal guidance?
[17:41] <Laurenceb> yeah
[17:41] <Laurenceb> http://wiki.ukhas.org.uk/_media/projects:imgp0191.jpg
[17:41] <Laurenceb> thats a photo a couple of weeks back
[17:41] <jatkins> neat
[17:41] <Laurenceb> the wings are on now and the radios fitted
[17:41] <jatkins> cool
[17:42] <jatkins> 434 mhz?
[17:42] <Laurenceb> yep
[17:42] <jatkins> one way ?
[17:42] <Laurenceb> yeah
[17:42] <jatkins> so fully autonomous?
[17:42] <Laurenceb> its hard to do uplink, but thats what jcoxons prize is about
[17:42] <Laurenceb> yeah
[17:42] <jatkins> yeah
[17:42] <jatkins> cool
[17:43] <jatkins> how do you control it without pitch + yaw?
[17:43] <shellevil> what's the 5 pin TO* device?
[17:43] <Laurenceb> its a buck reg
[17:43] <Laurenceb> for the servo
[17:44] <shellevil> ah
[17:44] <Laurenceb> theres a thermal fuse epoxied on the side
[17:45] <jatkins> what's the connector on the lassen iq?
[17:46] <jatkins> i used the pcb here http://embedtronics.com/GPS/lassenSQ.html
[17:46] <Laurenceb> I couldnt get hold of the right pitch ribbon cable connector - so its a SMD connector with cable epoxied on
[17:47] <jatkins> cool
[17:47] <Laurenceb> thats neat
[17:47] <jatkins> yeah
[17:47] <Laurenceb> diamond point sell the proper cables
[17:48] <jatkins> k
[17:49] <jatkins> ya know the sserial2mobile lib
[17:49] <jatkins> i've taken out the important stuff and put it here http://wiki.ukhas.org.uk/code:sms_arduino
[17:49] <jatkins> the rest of its for the email
[17:49] <Laurenceb> now I've got the firmware pretty well developed, it should be possible to make a SMD pcb version of that hardware
[17:49] <Laurenceb> nice
[17:50] <jatkins> cool
[17:50] <jatkins> what uc are you using?
[17:50] <Laurenceb> atmega168
[17:50] <jatkins> cool
[17:51] <jatkins> same one on the arduinos
[17:51] <jatkins> (well, atmega168v on the pro mini. 168 on the usb board)
[17:51] <jatkins> the phone connection is a trs connector
[17:52] <jatkins> will it have three separate wires if i cut a trs cable?
[17:52] <jatkins> tx, rx, gnd
[17:52] <Laurenceb> this is an rs232 cable?
[17:52] <jatkins> or would i need to solder directly to the cable
[17:52] <Laurenceb> or usb?
[17:52] <jatkins> http://en.wikipedia.org/wiki/TRS_connector
[17:53] <jatkins> for the sms
[17:53] <jatkins> i'll get the link for the actual cable
[17:53] <Laurenceb> erm isnt that the handsfree?
[17:53] <jatkins> it's stereo 3/32"
[17:53] <jatkins> oh.
[17:53] <jatkins> i've probably got the wrong one then :(
[17:53] <jatkins> how do you connect to do sms?
[17:54] <Laurenceb> check the manual for your phone
[17:54] <Laurenceb> you need a data connector
[17:54] <jatkins> oh
[17:54] <jatkins> ok
[17:54] <jatkins> what would it usually look like? i'm not sure if i've got the manual, it's an old phone i bought off my bro
[17:55] <Laurenceb> http://www.geardiary.com/wp-content/photos/IMG_0403.jpg
[17:55] <jatkins> thx
[17:55] <jatkins> ok
[17:56] <jatkins> i've just got two gold pins
[17:56] <jatkins> it's a very old phone
[17:56] <jatkins> nokia
[17:56] <Laurenceb> that will be for the battery
[17:56] <jatkins> oh
[17:56] <jatkins> i charged it with a different cable
[17:57] <jatkins> like a mini trs connector
[17:57] <Laurenceb> ok
[17:57] <Laurenceb> I dunno
[17:57] <jatkins> it probably doesn't do sms
[17:57] <Laurenceb> lookup the phone
[17:57] <jatkins> yeah
[17:57] <jatkins> i'll find the model number
[17:57] <Laurenceb> I need to head off, cya
[17:57] <jatkins> k
[17:57] <jatkins> cya
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[18:15] <jatkins[1]> ping edmoore
[18:19] <natrium42> hola
[18:19] <jatkins[1]> hi natrium42
[18:19] <natrium42> hi jatkins[1]
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[18:21] <jatkins[2]> oh..lan card accidentally came out
[18:21] <jatkins[2]> natrium42: i've probably asked this before, but have used the ntx2?
[18:21] <jatkins[2]> http://www.radiometrix.com/files/additional/ntx2nrx2.pdf
[18:22] <natrium42> nope
[18:22] <jatkins[2]> np
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[18:50] <jcoxon> hey jatkins
[18:50] <jatkins[2]> hey
[18:50] <jatkins[2]> are you good?
[18:51] <jcoxon> yes thanks
[18:51] <jcoxon> you?
[18:51] <jatkins[2]> yeah, good thx
[18:51] <jatkins[2]> have you used ntx2 http://www.radiometrix.com/files/additional/ntx2nrx2.pdf ?
[18:51] <jatkins[2]> (can't remember if i've asked you before :)
[18:52] <jatkins[2]> ..or know how it works?
[18:52] <jatkins[2]> it looks like its just serial
[18:52] <jatkins[2]> it says 3v = high 0v = low (cmos)
[18:52] <jcoxon> jatkins[2], yeah i've used one
[18:53] <jatkins[2]> cool
[18:53] <jcoxon> actually there are even better then just that
[18:53] <jatkins[2]> cool
[18:53] <jcoxon> they vary their freq acording to the voltage you give them
[18:53] <jatkins[2]> analogue?
[18:53] <jcoxon> yeah
[18:53] <jcoxon> you can treat them digitally
[18:54] <jatkins[2]> a-d?
[18:54] <jatkins[2]> well, d-a
[18:54] <jcoxon> you could do it with a DAC
[18:54] <jatkins[2]> yeah
[18:54] <jcoxon> or PWM with a low pass filter
[18:54] <jcoxon> or
[18:54] <jcoxon> use 2 pins and 2 resistors
[18:54] <jatkins[2]> pull-ups?
[18:55] <jcoxon> each pin has a different resistor and so when 1 pin is ON then it sends a particular voltage to the radio and so you get a tone on one freq
[18:55] <jatkins[2]> ok
[18:55] <jcoxon> then you switch to the other which produces a tone on another freq
[18:55] <jatkins[2]> yeah
[18:55] <jatkins[2]> is it binary?
[18:55] <jcoxon> if you carefully chose the resistors you can get nice shifts to do RTTY
[18:55] <jatkins[2]> ascii over binary
[18:56] <jcoxon> thats how i adapted rjharrisons rtty code to work on the arduino
[18:56] <jatkins[2]> is it on the wiki?
[18:56] <jcoxon> ummm no but i could put it up for you
[18:56] <jcoxon> one sec
[18:56] <jatkins[2]> thx
[18:57] <jcoxon> which arduino do you have?
[18:57] <jatkins[2]> pro mini
[18:57] <jatkins[2]> http://www.sparkfun.com/commerce/product_info.php?products_id=8824
[18:57] <jatkins[2]> i don't know if it has adc's
[18:57] <jatkins[2]> http://www.arduino.cc/en/Main/ArduinoBoardProMini
[18:57] <jatkins[2]> it has pwms
[18:57] <jatkins[2]> so should work
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[18:57] <jcoxon> oooo glad that you have the pro mini
[18:57] <jcoxon> its on 3.3v so you just need resistors
[18:58] <jatkins[2]> great :)
[18:58] <jatkins[2]> so just analogWrite()
[18:58] <jcoxon> no no
[18:58] <jcoxon> go for the resistors
[18:58] <jcoxon> http://www.pegasushabproject.org.uk/wiki/doku.php/ideas:notes
[18:58] <jatkins[2]> thx
[19:01] <jatkins[2]> ..just reading through it
[19:02] <jcoxon> i also put the resistors i used to get a nice decodable shift
[19:02] <jatkins[2]> would i need them on the pro mini?
[19:04] <jcoxon> thats what i was using
[19:04] <jatkins[2]> 2k2 = 2.2 kohms?
[19:05] <jcoxon> if you had a normal arduino you'd need a voltage divider to reduce the voltage
[19:05] <jatkins[2]> yeah
[19:05] <jcoxon> but the mini runs at 3.3v so all is good
[19:05] <jcoxon> 2K2 is 2.2K
[19:05] <jatkins[2]> yeah
[19:05] <jatkins[2]> ok
[19:05] <jatkins[2]> i've probably got them
[19:05] <jcoxon> you can use what ever you want but i found that worked well
[19:06] <jcoxon> do you have a radio to decode the transmission?
[19:06] <jcoxon> so you can check it all works?
[19:06] <jatkins[2]> no, i don't have the rx or tx yet
[19:06] <jatkins[2]> - just trying to learn a little
[19:06] <jatkins[2]> but i'll get both
[19:07] <natrium42> yo jcoxon
[19:07] Action: natrium42 has been organizing the shipment :S
[19:07] <jcoxon> hey natrium42 cool
[19:07] <jcoxon> i emailed steve to see how the HF is going
[19:07] <natrium42> basically, i ship it to a hotel but without staying in hotel :)
[19:08] <jcoxon> okay
[19:08] <natrium42> and then request it to be held at fedex location
[19:08] <natrium42> so it doesn't even get to hotel
[19:08] <natrium42> tricky stuff :)
[19:08] <jcoxon> okay
[19:08] <jcoxon> hehe
[19:09] <natrium42> ended up costing $98
[19:09] <jcoxon> okay
[19:09] <natrium42> but without my shipping discounts it would have been $166
[19:09] <natrium42> :)
[19:10] <jcoxon> good work
[19:10] <jcoxon> still nothing about valves today
[19:11] <natrium42> did you try calling them?
[19:11] <jcoxon> i've been in contact by email - they said they were sending me by post a quote
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[19:31] G8KHW (n=Steve@217.47.75.27) joined #highaltitude.
[19:31] <jcoxon> hey G8KHW
[19:33] <G8KHW> yo chaps and chapesses (well you ca always hope)
[19:33] <jcoxon> haha
[19:34] <jcoxon> indeed you can
[19:34] <jcoxon> got my antenna up
[19:35] <jcoxon> 20m of wire over the top of my roof
[19:35] <G8KHW> worked anyone yet?
[19:35] <jcoxon> no the SWR is bad
[19:35] <jcoxon> but much better reception
[19:35] <G8KHW> yeah - you (like me) need an ATU
[19:36] <G8KHW> that is one of my next jobs
[19:36] <jcoxon> :-)
[19:36] <jcoxon> hows the HF transmitter going?
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[19:37] <G8KHW> Ok - sent off for the board - working on the MFSK
[19:37] <G8KHW> need to talk to that Laurenceb chap
[19:37] <jcoxon> which board did you go for in the end
[19:37] <jcoxon> ?
[19:38] <G8KHW> RockMite-40
[19:38] <G8KHW> methinks that 7M would be best
[19:39] <jcoxon> yeah, though its quite crowded
[19:39] <G8KHW> actually it doesn't look that difficult to convert to most bands - just some component changes
[19:40] <G8KHW> yeah - but we could hop around a bit within the pull range of the crystal
[19:40] <jcoxon> okay
[19:41] <jcoxon> and you're thinking MFSK as the format
[19:44] <G8KHW> yes - just frequency shift to consider much simpler than BPSK-31
[19:44] <G8KHW> to generate - and about the same performnce by my estimate
[19:45] <jcoxon> okay, from my memory laurence had some difficulty with MFSK and thats why he ended up using domino
[19:45] <G8KHW> oh - any idea why?
[19:46] <G8KHW> I have been wanting to talk to him about his MSFK implemntation all weekend
[19:46] <jcoxon> hehe will shall capture him for you
[19:46] <G8KHW> but he wasn't on when I was
[19:47] <G8KHW> I had a look at his code - seems reasonably understandable and similar to the MFSK documentation
[19:48] <jcoxon> okay
[19:48] <G8KHW> but I have the odd Q
[19:48] <jcoxon> so is the plan to have a PIC onboard which does the hard work and then natrium's flight computer just sends serial?
[19:48] <G8KHW> yes - just need to define a data format
[19:49] <jcoxon> okay cool
[19:49] <jcoxon> sounds good
[19:49] <jcoxon> have you seen my hysplit models?
[19:49] <G8KHW> somthing simple - like a line of text with a carrage returm
[19:49] <G8KHW> nope
[19:49] <jcoxon> e.g. http://spacenear.us/gfs/2009-02-23-3.png
[19:50] <jcoxon> basically i'm running the system everymorning and it predicts the next 6 days
[19:50] <jcoxon> http://spacenear.us/gfs/
[19:51] <G8KHW> looks good
[19:52] <jcoxon> and the balloons have been made and natrium having them shipped this week
[19:52] <jcoxon> flight comptuer pcb is being made
[19:52] <jcoxon> so now to sort out the ballast tank
[19:53] <G8KHW> any thoughts
[19:53] <G8KHW> ?
[19:54] <G8KHW> (on the ballast tank)
[19:54] <jcoxon> ummm, denatured alcohol
[19:54] <G8KHW> yeah - pump or valve?
[19:55] <jcoxon> miniture solenoid valves
[19:55] <jcoxon> though i'm finding them suprisingly hard to get hold of
[19:55] <jcoxon> natrium42, suggested http://www.pegasushabproject.org.uk/wiki/doku.php/private:cross:ballast
[19:55] <jcoxon> for redundent valves
[19:55] <jcoxon> also laurence has a level sensor for the tank
[19:55] <G8KHW> will the DA just evaporate at that pressure/tempreture?
[19:56] <jcoxon> its a good point
[19:56] <jcoxon> Snox used it
[19:57] <G8KHW> maybe it will just boil off
[19:57] <jcoxon> its not going to freeze
[19:58] <jcoxon> boiling point is 78.4
[19:59] <G8KHW> or possibly a small pump immersed in the liquid - there are some very small pumps used for battery driven indoor water fountains
[19:59] <jcoxon> and then pump the ballast out?
[19:59] <G8KHW> yeah 78.4 at 1 atmosphere - but at 20K ft?
[19:59] <G8KHW> yeah
[20:00] <jcoxon> 20kft hmmm going point
[20:00] <shellevil> I was wondering about something really simple - a ball bearing lifted by a solenoid
[20:01] <G8KHW> yeah - we use somthing similar for nitrus oxide on rocketry
[20:01] <jcoxon> G8KHW, if it was a relatively sealed container with ethanol in it and some did evaporate it would still remain within the container
[20:02] <G8KHW> yes
[20:02] <jcoxon> shellevil, i could do some quick experiments
[20:02] <jcoxon> G8KHW, the evaporated ballast might come in useful near the end of the flight if it condenses
[20:02] <jcoxon> even more to dump :-p
[20:02] <G8KHW> http://cgi.ebay.co.uk/Indoor-Water-Fountain_W0QQitemZ110353344140QQcmdZViewItemQQptZUK_HomeGarden_Garden_PondsWaterFeatures_UK?hash=item110353344140&_trksid=p3286.c0.m14&_trkparms=72%3A1683%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318
[20:03] <jcoxon> isn't pumping though a lot more work then a solenoid valve thats normall closed and when opened just uses gravity
[20:04] <G8KHW> sure - but we are only talking about a few minutes of operation tops
[20:05] <G8KHW> Actually I may have an old one in the loft
[20:06] <G8KHW> even cheaper http://cgi.ebay.co.uk/DOLPHIN-INDOOR-BATTERY-WATER-FEATURE-IDEAL-GIFT-BNIB_W0QQitemZ220363779680QQcmdZViewItemQQptZUK_Home_Garden_Decorative_Accents_LE?hash=item220363779680&_trksid=p3286.c0.m14&_trkparms=72%3A1683%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318
[20:07] <jcoxon> its beautiful :-p
[20:07] <G8KHW> (gosh that looks ugly)
[20:07] <G8KHW> a find addition to any home
[20:07] <jcoxon> could it freeze? the pump
[20:07] <jcoxon> i guess not if immersed in ethanol
[20:08] <G8KHW> yeah - not sure what ethanol will do to the seals though
[20:09] <shellevil> they tend rto be heavy
[20:09] <shellevil> andAC only
[20:09] <shellevil> oh
[20:09] <jcoxon> these are battery powered
[20:09] <jcoxon> we could just drop the dolphin fountain as ballast
[20:09] <G8KHW> I doubt the pump will be much more than 40g
[20:09] <shellevil> I wondered about that.
[20:10] <shellevil> hot-glue, resistors, weights
[20:11] <shellevil> I came up with a simple funnel shape on the end of a cylinder, with a solenoid round the cylinder, and a steel ball bearing in the funnel.
[20:12] <shellevil> the solenoid pulls the ball up and allows ballast to flow out
[20:12] <jcoxon> shellevil, i like that idea
[20:13] <shellevil> you need magnetic bits to shape the field - but it's really simple
[20:15] <G8KHW> yeah - probably a solinoid coil and would do it (I have a few in the junk box if ayone wants to experiment - can ship)
[20:15] <jcoxon> yeah i'm happy to play
[20:15] <G8KHW> and some ball baerings
[20:16] <G8KHW> hang on I see what I can find now
[20:18] <jcoxon> bbiab food
[20:20] <shellevil> hmm. remember the vent hole, or you're pushing against 1 bar.
[20:27] hallam (i=836ff82e@gateway/web/ajax/mibbit.com/x-04d80a605c73a299) joined #highaltitude.
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[20:30] <rjharrison_> hi all
[20:30] <hallam> Hi rjharrison_
[20:30] <rjharrison_> how is your gps life going hallam
[20:30] <G8KHW> yo rjharrison_
[20:31] <rjharrison_> me thinks DX
[20:31] Action: rjharrison_ think dx even
[20:32] <rjharrison_> hi G8KHW
[20:33] <rjharrison_> I have been playing with antennas and have ordered a new toy
[20:33] <rjharrison_> http://www.mfjenterprises.com/Product.php?productid=MFJ-269
[20:35] <G8KHW> handy
[20:38] <rjharrison_> Yep I thought it may get may antennas to sing
[20:41] <hallam> rjharrison_: Haven't done much GPS work for a while, waiting for PCB and parts
[20:54] <G8KHW> BBIAB
[21:11] <jcoxon> hehe where is laurence when you need him
[21:15] Laurenceb (i=83e3dd23@gateway/web/ajax/mibbit.com/x-28474a7e0577a7d0) joined #highaltitude.
[21:15] <Laurenceb> hello
[21:16] <jcoxon> ooo Laurenceb, G8KHW would like to discuss MFSK with you
[21:16] <jcoxon> ping G8KHW
[21:16] <G8KHW> hi laurenceb - just need a chat about your MFSK
[21:16] <Laurenceb> k
[21:16] <G8KHW> but 1st - http://imagebin.org/39131
[21:16] <Laurenceb> yeah that code on the wiki is early days
[21:16] <jcoxon> G8KHW, does it work well?
[21:17] <Laurenceb> feel free to get it working :P
[21:17] <G8KHW> this works quite well the solinod plunger sits on top of the ball bearing and when activated picks it up - about 4mm
[21:17] <Laurenceb> interesting idea, for ballast ?
[21:17] <G8KHW> yeah
[21:17] <G8KHW> using the ball baering for a seal
[21:17] <Laurenceb> ah yeah
[21:17] <G8KHW> against a round hole
[21:18] <Laurenceb> yeah, the sensortechnics valves say down to -50C
[21:18] <Laurenceb> but they look jamble
[21:18] <Laurenceb> *jam - able
[21:18] <jcoxon> Laurenceb, and hard to get hold off
[21:18] <jcoxon> of*
[21:18] <Laurenceb> yeah
[21:18] <Laurenceb> RS sell loads of o rings
[21:18] <G8KHW> Laurenceb: anyway - so MSK - you didn't get it working then?
[21:18] <Laurenceb> this + an o ring should be cool
[21:18] <Laurenceb> not really
[21:19] <Laurenceb> I suspect its an endianess issue
[21:19] <G8KHW> what didn't work
[21:19] <Laurenceb> the documentation is quite poor
[21:19] <G8KHW> ah ok
[21:19] <Laurenceb> well it was complete garbage out
[21:19] <G8KHW> so you implemnted it from scratch?
[21:19] <Laurenceb> but there were about 16 ways of doing it
[21:19] <Laurenceb> yeah
[21:20] <Laurenceb> have you looked at my code?
[21:21] <G8KHW> oh yes
[21:21] <G8KHW> reasonably understandable
[21:21] <Laurenceb> I tried to make it as fast and light as poss, so everything is done with bit shifts ect
[21:22] <Laurenceb> but it does mean you really have to know about endianess
[21:22] <Laurenceb> brb cooking
[21:22] <G8KHW> (Grey code implementation would be better done with a lookup table IMO)
[21:23] <G8KHW> and the FEC stuff could probably be done the same way - its like a CRC polynomial which can be done with a LUT
[21:24] <G8KHW> endianess shouldn't matter if you do it in C
[21:24] <Laurenceb> ok
[21:24] <Laurenceb> yeah, but its how yeah read the specs
[21:25] <G8KHW> yeas I agree its not well documented in the docs I have been able to find
[21:25] <jcoxon> give me one sec i've got cocoamodem's source
[21:25] <jcoxon> it has well documented code
[21:25] <jcoxon> i'll have a look
[21:25] <Laurenceb> http://www.qsl.net/zl1bpu/MFSK/
[21:25] <Laurenceb> is the best I found
[21:26] <Laurenceb> but I'm not sure mfsk is the best bet anymore
[21:27] <Laurenceb> ideally I'd go for something written from scratch based on packet
[21:27] <G8KHW> ? - seems as good as BPSK-31 and simpler to implement
[21:27] <Laurenceb> but its a lot of work
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[21:27] <G8KHW> yeah its a trade off - improvements vs effort
[21:27] <Laurenceb> yeah, but it doesnt give guarenteed packet integrity
[21:27] <Laurenceb> yeah
[21:29] <G8KHW> Not too worried about packet integrity in most situations a simple CRC will tell you if the packet is corrupt or not (at least within sensible probability bounds)
[21:29] <Laurenceb> something written from scratch incorporating a reed solomon encoded packet could give data in data out with zero errors
[21:29] <Laurenceb> yeah, but without FEC you get high loss
[21:30] <G8KHW> yep but thats a lot of work - at least with existing modes you don't have to worry about a decoder
[21:30] <jcoxon> remember we need other people to easily decode it
[21:30] <Laurenceb> and adding reed solomon to RTTY doesnt look too hopeful
[21:30] <Laurenceb> as RTTY has a habit of adding characters
[21:30] <Laurenceb> yeah thats a big + for MFSK
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[21:32] <jcoxon> hmmmho
[21:32] <jcoxon> how about dominoEX?
[21:32] <Laurenceb> no FEc
[21:32] <G8KHW> gMFSK looks like a good starting point - reasonably easy to understand
[21:33] Action: shellevil ponders.
[21:33] <Laurenceb> the source?
[21:33] <Laurenceb> ok sounds good
[21:33] <shellevil> You could add FEC info to ascii letters by doing random CaPS
[21:33] <G8KHW> I thought dominoEx 16+ did have FEC
[21:33] <Laurenceb> yeah but it makes it sloooowwww
[21:34] <Laurenceb> MFSK is almost as fast as 300 baud RTTY
[21:34] <jcoxon> but we aren't looking for speed
[21:34] <G8KHW> Dominoex 16 and MSFK 16 looked similar in the results I saw
[21:35] <G8KHW> narrow bandwidth is the key to longrange comms
[21:35] <hallam> jcoxon: not looking for speed? try http://www.ussc.com/~turner/qrss1.html
[21:35] <jcoxon> hehe i read that today - from hackaday?
[21:36] <jcoxon> but we aren't really looking for speed are we?
[21:36] <jcoxon> we want range - we thats what i think at least
[21:36] <hallam> yeah, I saw it from hackaday
[21:36] <hallam> jcoxon: true, but more than 1 word per hour would be nice :P
[21:37] <Laurenceb> well if you take the horizon range limit of ~500Km
[21:37] <G8KHW> not a problem for HF
[21:37] <Laurenceb> and a 10mw module you should be able to get well over 1Kbps
[21:37] <Laurenceb> yeah
[21:38] <Laurenceb> but the background noise is stronger
[21:38] <jcoxon> also the plan is to have multiple receievers
[21:38] <Laurenceb> yeah... I was thinking for gliders/rockets and the like on 434/868
[21:39] <G8KHW> so laurence - did yu get dominoex working?
[21:39] <Laurenceb> yeah no probs with that
[21:39] <Laurenceb> codes on the wiki again :P
[21:39] <G8KHW> but the sort without fec
[21:39] <Laurenceb> brb
[21:39] <G8KHW> yeah i looked at it - rather short I thought
[21:44] <Laurenceb> thats cuz its simple :P
[21:45] <G8KHW> yeah - sorry I dismissed it as too short to be finished - however its probably too short becuse no FEC
[21:46] <G8KHW> part of the problem is my windows PC not displaying unix text files properly
[21:48] <Laurenceb> yeah I have that problem
[21:48] <jcoxon> stupid windows
[21:49] <G8KHW> This is where I got most of my infor on MFSK - did u find anything better laurenceb?
[21:49] <G8KHW> http://www.qsl.net/zl1bpu/MFSK/
[21:49] <Laurenceb> jcoxon: I think this AD7746 cap sensor must be busted somehow
[21:49] <Laurenceb> G8KHW: no, that was the best I found
[21:49] <G8KHW> :-(
[21:50] <jcoxon> G8KHW, did you use a linear solenoid then for that valve demo?
[21:50] <jcoxon> Laurenceb, oh crap
[21:50] <jcoxon> what should we do?
[21:50] <Laurenceb> well I could probably desolder it
[21:50] <Laurenceb> and fit a new one
[21:50] <G8KHW> I looked at the fldigi implementation too - not as easy to understand as yours
[21:51] <G8KHW> jcoxon - do you want me to slip it in the post?
[21:51] <G8KHW> U can play
[21:51] <Laurenceb> I just cant understand, if I turn off the excite output it gives random noise
[21:51] <jcoxon> G8KHW, yeah that would be great
[21:51] <Laurenceb> but if the output is on it reads 0xFFFFFF or 0x000000
[21:52] <Laurenceb> also it doesnt talk properly over I2C at 3.3v
[21:52] <Laurenceb> and the temp sensor reports a perminant busy status
[21:53] <jcoxon> Laurenceb, that doesn't sound good/reliable
[21:53] <Laurenceb> no... but I was pretty careful
[21:54] <jcoxon> yeah
[21:54] <jcoxon> i know
[21:54] <Laurenceb> maybe the front end is extremely esd sensitive
[21:54] <Laurenceb> I could try it with a new IC in the lab at work
[21:55] <jcoxon> how about my IR distance sensor
[21:55] <jcoxon> concept
[21:55] <jcoxon> not as accurate but off the shelf
[21:55] <Laurenceb> not sure how well it will reflect
[21:56] <Laurenceb> and I've got the hardware ready
[21:56] <Laurenceb> and it talks over I2C
[21:57] <Laurenceb> hopefully its just a fluke incident
[21:59] <jcoxon> yeah
[22:00] <hallam> Laurenceb: What's the capacitance sensor for?
[22:00] <Laurenceb> determining the level of ballast in the tank
[22:01] <Laurenceb> it also has a humidity sensor hooked up to the second channel
[22:03] <hallam> could use a load cell in the balloon tension path?
[22:04] <Laurenceb> yeah maybe
[22:04] <Laurenceb> temperature drift would be an issue
[22:05] <jcoxon> hallam, IR distance sensor from the top of the tank - thats my idea :-p
[22:06] <G8KHW> jcoxon: it will be in the post tomorrow
[22:06] <G8KHW> BBL
[22:06] <jcoxon> G8KHW, thanks
[22:06] <jcoxon> i'll bbl as well
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[22:54] <jcoxon> mwhaha i've got access to the Kings College labratory ordering system
[22:55] <jcoxon> tempted to purchase a genome
[22:55] <Laurenceb> nitric acid?
[22:55] Action: Laurenceb consults the anarchists cookbook
[22:56] <SpeedEvil> Rocket fuel!
[22:56] Action: SpeedEvil puts in an order for 100l of 95% H2O2
[22:57] Action: jcoxon is searching for nitric acid
[22:58] <jcoxon> 1g of nitric acid is ?209
[22:58] <SpeedEvil> That's probably absurd purity.
[22:59] <jcoxon> 99% 15N
[22:59] <jcoxon> :p
[22:59] <Laurenceb> 15M ?
[22:59] <SpeedEvil> Yeah - but it's made by vacuum chromatography or something to eliminate the last traces of plutonium.
[22:59] <Laurenceb> plutonium ?!
[23:00] <SpeedEvil> (your element may vary)
[23:00] <SpeedEvil> Fun thought.
[23:00] <jcoxon> uranium wire 0.5mm 99% purity ?264
[23:01] <SpeedEvil> Take a hydroponic growing system, some cylinders of fossil CO2, and you can make 'old' papyrus.
[23:01] <jcoxon> right i better stop
[23:01] <Laurenceb> hehe
[23:01] <jcoxon> its my flat mates account
[23:01] <jcoxon> she might get in trouble
[23:01] <Laurenceb> guess its depleted or unenriched
[23:02] <SpeedEvil> A bit more effort, and you can make radiocarbon 'old' fried chicken.
[23:04] <jcoxon> Uranium atomic absorption standard solution 1,000??g/mL U in 1 wt. % HNO3 (Exact U concentration on label)
[23:04] <jcoxon> Please note that the delivery on this item is ?200 due its Thorium/Uranium properties and the costs involved in the delivery of such sensitive materials.
[23:04] <Laurenceb> haha
[23:04] <jcoxon> its too much fun
[23:05] <SpeedEvil> Hmm.
[23:05] <SpeedEvil> Self-heating balloons.
[23:05] <SpeedEvil> How much is tritium?
[23:05] <Laurenceb> MIR
[23:05] <Laurenceb> unfortunately that concept needs about a 10m diameter
[23:06] <jcoxon> Deuterium oxide 99.9 atom % D, tritium ~150?dpm/mL
[23:06] <jcoxon> 803 pounds
[23:06] <Laurenceb> for how much?
[23:06] <jcoxon> oh its 803 gbp
[23:07] <Laurenceb> 803 for what quantity?
[23:07] <natrium42> i am getting a tritium keychain from DX soon :P
[23:07] <Laurenceb> SpeedEvil: http://ballons.cnes.fr:8180/html/mir/mir_gb.htm
[23:07] <jcoxon> 1kg
[23:07] <Laurenceb> oh ok ;P
[23:07] <Laurenceb> natrium42: yeah those are cool
[23:10] <SpeedEvil> I've got a couple.
[23:10] <SpeedEvil> I'm planning on upgrading to an LED based one - which I'm in the process of designing.
[23:10] <Laurenceb> wut
[23:11] <Laurenceb> the whole point is the tritium
[23:11] <natrium42> srsly
[23:11] <jcoxon> natrium42, did you catch the stuff about the radio from G8KHW
[23:11] <SpeedEvil> about the same size, ~6months battery life, consistent glow, and .1ms 0.5W pulses every 10s.
[23:11] <natrium42> yep, i just read the backlog
[23:12] <SpeedEvil> Laurenceb: yes - it's not actually very bright, even compared to something that needs to last months on a tiny battery.
[23:12] <natrium42> SpeedEvil, it's not cool w/o tritium :P
[23:12] <SpeedEvil> natrium42: there is that.
[23:12] <SpeedEvil> I do have tritium balls.
[23:12] <SpeedEvil> 2*15mm dia green ones :)
[23:12] <natrium42> i have tritium in my watch dial
[23:12] <SpeedEvil> And a 5*50mm rod.
[23:12] <SpeedEvil> candlepowerforums/ebay++
[23:13] <natrium42> do they glow too?
[23:13] <SpeedEvil> yes
[23:13] <SpeedEvil> about the same surface brightness as the keychain ones - just bigger.
[23:13] <SpeedEvil> As a reference point.
[23:14] <SpeedEvil> The keychain, in a completely dark room - is an adequate walk-around smooth places without bumping into large things light
[23:14] <hallam> I once worked out how many of those you'd need to build a poor man's RTG with solar cells
[23:14] <SpeedEvil> And you can read by it with it pressed right up to the object
[23:14] <hallam> answer: too many
[23:14] <SpeedEvil> oodles.
[23:15] <natrium42> hallam, can't you use your fusor :P
[23:15] <Laurenceb> hallam: just buy a boat and sail to siberia
[23:15] <natrium42> freaky --> http://science.nasa.gov/headlines/y2004/16aug_solder.htm
[23:16] <Laurenceb> plenty of RTGs hanging about
[23:16] <natrium42> haha, you mean abandoned light towers, etc?
[23:17] <Laurenceb> http://upload.wikimedia.org/wikipedia/en/thumb/d/d9/Soviet_RTG.jpg/250px-Soviet_RTG.jpg
[23:18] Last message repeated 1 time(s).
[23:18] <Laurenceb> even space to pull up your boat behind
[23:18] <natrium42> Laurenceb, http://englishrussia.com/?p=2198
[23:18] <G8KHW> A lesson about ordering stuff up without due care:-
[23:19] <G8KHW> A mate of mine was developing image intensifiers once (form ilatary application)
[23:19] <G8KHW> - the sort with high voltage used to accelerate electrons onto a phosphor plate.
[23:19] Action: Laurenceb sets sail
[23:19] <G8KHW> He needed somthing to discharge the tube fast when it saw a gun flash - so as not to be blinded for a few secs.
[23:19] <G8KHW> So he cam across a device that seemed to do the job a - and ordered one up. The next thing he knew he was
[23:19] <G8KHW> being interviewd by HMG for trying to obtain devices used in atomic wepons.
[23:19] <SpeedEvil> I vaguely recall that the emission of light from the keychain thing is about a microwatt.
[23:20] <Laurenceb> G8KHW: ignatron or one of those odd devices?
[23:20] <SpeedEvil> The notion that you can keep the lid on weapons tech is damn silly.
[23:20] <natrium42> ahaha
[23:20] <natrium42> G8KHW, that's crazy :D
[23:21] <SpeedEvil> I remember a comment from someone that'd seen both that lithotriptors (kidney stone ultrasonic breakers) and atomic weapons triggers look very similar.
[23:22] <Laurenceb> natrium42: and people worry about dirty bombs
[23:22] <Laurenceb> lol
[23:22] <G8KHW> I think the device is used to simltainiulsy trigger charges with high timing accuracy
[23:22] <Laurenceb> yeah
[23:22] <Laurenceb> they use some odd valve devie
[23:22] <Laurenceb> basically a triggered spark gap
[23:22] <SpeedEvil> Going back to first principles, the brightness of the keychain is about a 4th magnitude star at 30m
[23:23] <SpeedEvil> this is 0.7nw/m^2 or so
[23:23] <G8KHW> somthing like that
[23:23] <SpeedEvil> so that's about 12000 times that,
[23:23] <SpeedEvil> or 10uW or so.
[23:27] <Laurenceb> http://www.bellona.no/bellona.org/english_import_area/international/russia/navy/northern_fleet/incidents/37598
[23:27] <Laurenceb> hmm
[23:27] Action: Laurenceb forwards to osama
[23:30] <G8KHW> eeek
[23:30] <Laurenceb> An RTG was found ravaged by non-ferrous metal looters. The RHS core was found emitting 1000 R/h of radiation at a bus stop
[23:30] <Laurenceb> WTF
[23:34] <G8KHW> nights
[23:34] G8KHW (n=Steve@217.47.75.27) left irc: "Leaving"
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[23:40] jcoxon (n=jcoxon@host86-146-165-98.range86-146.btcentralplus.com) joined #highaltitude.
[23:51] <Laurenceb> http://www.howtogeek.com/howto/linux/stupid-geek-tricks-watch-movies-in-your-linux-terminal-window/
[00:00] --- Tue Feb 24 2009