highaltitude.log.20060802

[00:32] <phatmonkey> parachute ordered, yay
[00:32] <phatmonkey> http://spherachutes.com/ - highly recommended
[00:32] <phatmonkey> prompt replies to questions and they're customising it for me
[00:41] <phatmonkey> gawd, i hope, k7- something's balloon is alright
[01:32] kc0wys (n=macfreak@adsl-70-238-164-190.dsl.stlsmo.sbcglobal.net) joined #highaltitude.
[01:32] <kc0wys> hey all
[01:34] <Tiger^> hey
[01:34] <Tiger^> how did it go?
[01:35] <kc0wys> not so good :(
[01:36] <kc0wys> great flight, and the signal was maintained throughout the flight, but the comptuer's voltage regulator overheated after 3 minutes and so i lost all gps/imagery data -- it's lost
[01:36] <Tiger^> oh
[01:36] <Tiger^> damn :/
[01:36] <kc0wys> I'm hoping someone finds it and calls
[01:36] <kc0wys> yeah
[01:36] <Tiger^> not good
[01:37] <Tiger^> but remember, the guy from KNSP lost his first payload
[01:37] <kc0wys> but like i said, i'm really looking forward to the second balloon
[01:37] <kc0wys> ya
[01:37] <Tiger^> yeah
[01:49] <kc0wys> i'll post the first (and last) image from the balloon in a minute...
[01:50] <krim_> im sorry for your balloon kc0wys :/
[01:53] <kc0wys> yeah it's quite a bummer
[01:57] <Tiger^> maybe someone will find it.
[01:57] <kc0wys> yea
[01:57] <kc0wys> the air traffic control tower guy was ticked
[01:58] <kc0wys> he said "you have no idea where it is, and you're just now calling me!!?!"
[01:58] <Tiger^> hmm
[01:58] <Tiger^> weird
[01:59] <krim_> no radar reflector ?
[01:59] <kc0wys> uhh
[01:59] <kc0wys> heh
[01:59] <kc0wys> no
[01:59] <krim_> ehehehe
[01:59] <kc0wys> yeah i didn't think it would really help anyways
[01:59] <kc0wys> ah well if there was a problem i'd already know about it
[02:00] <kc0wys> my next one will most definitely have a reflector on it
[02:01] <krim_> yup atc could help you pinpoint the last location it was observed
[02:03] <phatmonkey> bummer :[
[02:03] <phatmonkey> is the radio still up?
[02:03] <phatmonkey> you could locate the signal
[02:03] <krim_> and most important of all, no planes would fly into it, i know its quite extraordinary but better safe than sorry
[02:04] <kc0wys> well no
[02:04] <krim_> :(
[02:04] <kc0wys> since it's no longer LOS there is no signal
[02:04] <kc0wys> but technically the radio is probably still transmitting
[02:04] <phatmonkey> have a drive in the rough direction in went in, you might pick up a faint signal
[02:04] <phatmonkey> worth a try!
[02:04] <phatmonkey> bad luck though man
[02:04] <kc0wys> yeah
[02:05] <phatmonkey> make sure you keep the next one simple and make sure you finalise it a week before you launch so you can test test test
[02:05] <phatmonkey> push the launch back a few weeks if you have to, just don't rush it
[02:06] <kc0wys> yeah
[02:06] <kc0wys> i didn't really like my approach
[02:07] <kc0wys> point-to-point wiring on prototyping pcb's, all linear regulators (=lots of heat), a full laptop computer, 40 lithium AAs, etc
[02:07] <kc0wys> this next one will be a bit simpler
[02:07] <phatmonkey> hehe, yeah
[02:07] <kc0wys> i mean, the laptop would have worked fine had power consumption not been an issue
[02:08] <kc0wys> physically, both its weight and size was not an issue
[02:08] <kc0wys> but 10 watts is a lot, especially when most of that is heat
[02:09] <phatmonkey> do you have any suggestions for hooking up the gps, radio and things to a GPIO so i can switch them off?
[02:09] <phatmonkey> not that hot with electronics
[02:10] <phatmonkey> i can probably keep the gumstix alive for 3, 4 maybe 5 days with the batteries i'm using
[02:10] <phatmonkey> it would be nice to switch everything off to maximise that time if it's lost
[02:11] <kc0wys> wow that's a long time
[02:11] <kc0wys> which is a good thing ;)
[02:11] <kc0wys> ya
[02:12] <kc0wys> use power or darlington transistors to switch them off and on with the GPIO port
[02:12] <kc0wys> if something pulls a lot of current you may want to use MOSFETs but generally they're more trouble than they're worth
[02:12] <kc0wys> you will lose *some* power to the transistors, but that's more or less proportional to a. the input voltage and b. the current
[02:13] <phatmonkey> ok
[02:13] <kc0wys> GPIO are just pins that can be turned high or low by the gumstix, right?
[02:13] <phatmonkey> yep
[02:15] <phatmonkey> just sitting here, the gumstix and robostix are drawing 150ma
[02:16] <phatmonkey> 13.2Ah at 7.4v on the batteries
[02:16] <phatmonkey> that's going to be quite a long time!
[02:17] <kc0wys> !!
[02:17] <kc0wys> that's great!
[02:17] <phatmonkey> how could i measure the voltage of the batteries?
[02:17] <phatmonkey> yeah, radio is probably going to draw only around 100ma too
[02:17] <phatmonkey> ... according to steve
[02:17] <kc0wys> o ok
[02:17] <kc0wys> does the gumstix have an analog to digital converter?
[02:18] <phatmonkey> robostix does, yep
[02:18] <kc0wys> since your batts are >5v, and i assume the max voltage your adc can take is 5v, then you'll need to use a simple resistor voltage divider
[02:18] <kc0wys> http://hyperphysics.phy-astr.gsu.edu/HBASE/electric/voldiv.html
[02:19] <kc0wys> use trial and error to get values for the resistors to bring the open circuit voltage to <5v
[02:19] <kc0wys> then some simple math in your program can convert the value from the adc to its actual voltage
[02:19] <kc0wys> (this is what i did)
[02:20] <phatmonkey> alrighty
[02:20] <kc0wys> and here's the darlington idea i mentioned for switching on/off your devices: http://www.me.umn.edu/courses/me2011/robot/technotes/motorswitchled/index.html
[02:20] <kc0wys> the diagram is a bit dodgey but that should work
[02:20] <phatmonkey> ah yes, great
[02:20] <phatmonkey> thanks
[02:21] <kc0wys> (replace the motor in the schematic with your device)
[02:21] <kc0wys> np
[02:23] <phatmonkey> everything runs at 5v, which is a relief
[02:23] <kc0wys> ah ok that's really nice
[02:23] <phatmonkey> gumstix, robostix, gps, servos, thermopile thing
[02:23] <phatmonkey> actually, i dunno about the radio
[02:23] <kc0wys> i have come to hate linear voltage regulators
[02:24] <kc0wys> tis what killed my balloon >:o
[02:24] <phatmonkey> damn, yeah :(
[02:24] <phatmonkey> http://www.v-infinity.com/adtemplate_child.asp?c=1003783&p=1003782&catky=328060&subcatky1=248699&subcatky2=910487
[02:24] <phatmonkey> i'll probably use that
[02:26] <kc0wys> hmm its efficiency is only 75% o.O
[02:26] <kc0wys> there's better, but probably at a price
[02:26] <kc0wys> but hey i can't complain
[02:26] <phatmonkey> hmm, better efficiency would be good
[02:26] <kc0wys> what i had was 50% efficient, at best :P
[02:27] <kc0wys> btw i uploaded the images i received from ENSURE-1: http://kc0wys.homeunix.com/projects/ensure/index.html
[02:27] <phatmonkey> you got suggestions for DC-DC convertors?
[02:27] <phatmonkey> ah cool
[02:27] <kc0wys> not exactly -- that's something i'm going to be looking into for the next ENSURE
[02:28] <kc0wys> but i got really lucky, because we used all the helium in the tank, which turned out to be just enough
[02:29] <Tiger^> so use a step-up step-down converter
[02:29] <Tiger^> :)
[02:29] <phatmonkey> i highly recommend http://spherachutes.com/ btw
[02:29] <phatmonkey> very quick with answering my questions, and they're making me a custom chute
[02:30] <Tiger^> http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1742
[02:30] <phatmonkey> at *last* i have a parachute
[02:30] <kc0wys> hehe
[02:30] <Tiger^> input range from +1.8V to +11V. Typical efficiency when boosting battery inputs is 85%.
[02:30] <Tiger^> ;>
[02:30] <kc0wys> hehe
[02:31] <phatmonkey> nice
[02:31] <Tiger^> 250mA though
[02:31] <Tiger^> but they have chips with more juice
[02:31] <phatmonkey> yeah, that won't be enough for the servos
[02:31] <kc0wys> servos at 11v!??
[02:31] <kc0wys> you must have some monster servos!
[02:32] <kc0wys> or is it variable?
[02:32] <Tiger^> it's variable
[02:32] <Tiger^> you can make 5V out of 1.8V
[02:32] <Tiger^> in step-up mode
[02:32] <kc0wys> oh gotcha
[02:33] <Tiger^> hehe
[02:33] <Tiger^> http://pdfserv.maxim-ic.com/en/ds/MAX5073.pdf
[02:33] <phatmonkey> i'll work out a circuit for this voltage regulation, voltage monitoring and switching stuff and i can probably fit all on a single board
[02:33] <Tiger^> this puppy is 2A
[02:33] <Tiger^> ;)
[02:34] <phatmonkey> or maybe i shouldn't bother to start with to make it ultra simple
[02:34] <kc0wys> wow that's really impressive :D
[02:34] <phatmonkey> nice
[02:34] <Tiger^> i used a linear regulator
[02:35] <Tiger^> my whole avionics drew 500mA
[02:35] <Tiger^> the LM got pretty hot
[02:35] <Tiger^> around 60C
[02:36] <phatmonkey> i'd better get some sleep anyway, night
[02:36] <kc0wys> kk cya
[02:36] <kc0wys> i was pulling ~1A at 26v
[02:36] <Tiger^> nite phatmonkey
[02:36] <Tiger^> yeah, that's a lot
[02:36] <kc0wys> definitely
[02:36] <Tiger^> 26W
[02:36] <kc0wys> ya
[02:37] <kc0wys> hehe
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[09:02] <jcoxon> hey all
[09:03] <jcoxon> kc0wys, sorry to hear about ensure 1
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[00:00] --- Thu Aug 3 2006