Thanks everyone for your comments on foil. I have decided to leave the foil on the camera module for the BUNS balloon. It is attached with hot glue and is...
For some time I have been working on a cutdown unit for the BUNS balloon. It is a time delayed cutdown and consists of a 555 timer that drives a 4017b...
We considered that there isn't much Oxygen up there. We are just concerned for the case where it might get hung up in a tree or have an early burst for some...
... I would think that you would still have the chaos, the chaos is not so much the balloon popping but the lack of atmosphere to have the chute do much of...
3172
Art
KY1K@...
Jun 3, 2007 7:01 pm
I can't help you with the cut down issue you mention. But, I strongly suggest that you do not use an RC network to determine the delay before actuating the cut...
As well as the resistor also. we had a flight that used a resistor for a timing portion of a message. and because of the cold it went into hyper speed,, soo...
I'll be working on a GPSL 2007 shirt shortly - May has been a rather busy month. I'll be looking over the photos I have here, but if anyone has a high-quality...
What would you use instead of the resistor and capacitor? The cap I am using is a surface mount tantalum. The package is well insulated but, I have a hard...
3176
Art
KY1K@...
Jun 4, 2007 4:32 am
I'd forget tantalum and electrolytic, they have bad tempco and tolerances are generally -5 percent +40 percent. I'm not sure the electrolyte would be stable at...
Well I did the test in the freezer and here is what happened. I put the battery in insulation. I left the cutdown pcb (includes everything but the battery)...
3178
wb8elk@...
Jun 4, 2007 6:52 am
The problem I can see besides the timing components shifting with cold temperatures is if your ascent rate is not exactly 1000 ft/min....even the best laid...
Have you though about using a PICAXE microcontroller? You can set it's delay in software and run the burner for just a few seconds. Paul ... For some time I...
Thanks for doing this. I'll order one when it's ready and have it sent to my house. Paul ... I'll be working on a GPSL 2007 shirt shortly - May has been a...
I've not seen a problem with a small package sitting right on top of the parachute. I'd recommend placing it there rather than separating the 'chute and...
<raise hand> Oh, oh, oh!!!! What about a PICAXE and small pressure sensor? In fact, I think I'll begin designing that for my N&V column. Paul ... The problem I...
PICAXE website: http://www.rev-ed.co.uk/picaxe/ The 8-pin versions are $4. Nice alternative to PICs if you don't want to bother with getting/making a PIC...
One of the benefits of being a teacher is that I have the time to mess around with this stuff. Your idea is along the lines of what I was thinking. I'll add...
A guarded pushbutton switch (push on, push off) might work just as well, so the batteries for the PICAXE aren't run down doing nothing. You'd switch on the...
I'm looking at using a Silicon Micro's SM5612 pressure sensor. It should be similar to the 5812 I use in a balloon weather station. I agree with watching for...
3187
wb8elk@...
Jun 4, 2007 9:06 pm
One thing to note about solid state pressure sensors....I'd recommend using the conditioned and temperature compensated sensors that give you a 0 to 5V ...
3188
Mike Manes
manes@...
Jun 5, 2007 12:13 am
Yeah, thin air and possible trans-sonic local airflow probably have something to do with PBC. But the major culprit is parachute instability, as I discussed...
3189
Mike Manes
manes@...
Jun 5, 2007 12:13 am
Hi Brek, Sounds as though you're overdriving your burner. It only has to get hot enough to melt the lift line enough so that it pulls apart under tension....
3190
Mike Manes
manes@...
Jun 5, 2007 12:13 am
Hi Brek, Holy shamoley! The EOSS mechanical baro-armed release with backup burner weighs just 168 gm (0.4 lb) and is rigidly bound to the load risers at the ...
3191
Mike Manes
manes@...
Jun 5, 2007 12:15 am
Or, one could just build a 60-sec cycling DF beacon with a 30 sec listening period and a DTMF decoder to let you command a cutdown at will. It works well. 73...
3192
Mike Manes
manes@...
Jun 5, 2007 12:15 am
Hi Brek, Hmmm ... guess I should looked at the 4017 specs first. It's just a 5-bit BCD-coded counter, so 2 of 'em cascade will yield just a 100:1 clock from...
3193
Mike Manes
manes@...
Jun 5, 2007 12:15 am
To Brek's credit, he's running his 555 with a low enough RC time constant to avoid using electrolytics! Your suggestion to use a plastic vs ceramic cap is...
3194
Mike Manes
manes@...
Jun 5, 2007 12:17 am
Art's suggestion to use a domestic freezer as a cold soak chamber is is a good one. Although it only goes goes down to 0F (-16C), while one can see -80C at...
Chuckle, chuckle. Well in that 0.7 lb. I was leaving some room to add some duct tape. You know, just 4 or 5 wraps (each direction) to keep the lid closed....
I have most of the cutdown designed and because we have finals today, I think I can finish during class. It uses a PICAXE-04 and has a temperature and...
