Topics

My floating balloon plans

Jared Smith
 

Thanks for joining this list. The intent is to provide us a place to
discuss high altitude ballooning.

I'm making plans to launch at least two floating balloons later this
summer. These will be inexpensive, VERY small and lightweight payloads
(around .7 ounce total) with a 20 meter HF WSPR transmitter.
Everything will be controlled via a tiny Arduino micro-controller.
It's solar powered only (batteries are too heavy), so daylight
transmissions only. My goal is to get it to float as far as possible.

My general design is pretty similar to that of HIRFW-6 which has been
floating since September and has circled the globe 20+ times. You can
track it on APRS.fi or at
https://tracker.habhub.org/#!mt=roadmap&mz=3&qm=All&mc=20.52799,-20.29664&q=hirfw-6

My plans and a schematic are outlined at
https://docs.google.com/document/d/1Es1rbg2a9rPM2AEG23-Rvfko8uyDNknSzF_th0O7MnU/edit?usp=sharing

I'd be happy to hear your feedback, ideas, warnings, suggestions, etc.
I'm not much of a hardware person, so would love to have you
scrutinize this for flaws or help build it out. I have most of the
hardware already and am starting a prototype now. I'll let you know
how development progresses, and please let me know if you have any
questions.

Thanks,

Jared

PS - I believe the USU GAS team is planning a launch for this
Saturday. I'll send more details if/when I get them. They likely will
want some help with tracking and recovery.

Josh Jensen
 

Are you planning to release the source code as well for public scrutiny?

Jared Smith
 

Josh Jensenwrote:
Are you planning to release the source code as well for public scrutiny?
I'm happy to share with you guys initially. I'd *LOVE* the feedback.
My programming is not real strong (which is one of the reasons I'm
doing this).

If it all works, I'll certainly share publicly on GitHub or elsewhere.
I'm piecing together code from a lot of different sources - I've yet
to find a public repository with code that does everything I need.

I plugged in the Arduino last night and got my temperature sensor
working, so that's a good start. :-) Tonight I'm going to build and
test the WSPR transmitter. Then the GPS, followed by the solar cells
and power management system. Then I'll test A LOT to make sure it
actually all works in various conditions.

One thing I have learned already (the hard way) is to not go with
clone microcontrollers. The clone/knockoff I bought is printed on a
thicker PCB and weighs almost twice as much as the official Arduino
version I have.

Jared

ag1t@...
 

Jared,
 
  If you don't mind, I would like to clone your efforts.  If you would let me know where you purchase your equipment from, I will duplicate your setup and try working the code with you.  That way we can swap notes, etc.
 
  I hope to better my coding skills as well.  Plus, I could use my set of hardware to do temperature testing etc. against when you feel we are ready for it.
 
  Gary

Jared Smith
 

Gary -

I'd be happy to have you duplicate (or, better yet, improve upon) what I'm doing. If others are interested, it would make sense to combine orders to save on shipping. I'd be happy to coordinate this if others want to give it a go.

Most of the links to what I've purchased are in my Notes document - https://docs.google.com/document/d/1Es1rbg2a9rPM2AEG23-Rvfko8uyDNknSzF_th0O7MnU/edit?usp=sharing

You'd need to purchase the following:
  • Arduino Pro Mini ($10 - be sure to get the Arduino version, not a clone)
  • FTDI breakout module ($10 - only need 1 for programming)
  • Si5351A Clock Generator with TCXO ($15 plus $4 for their SMA End Launch Connectors)
  • GPS (~$25 plus shipping from the UK)
  • Supercapacitors ($4.81 each - need 2 per flight)
I have extras of most everything else you'd need and am happy to share:
  • Solar panels - I bought a pack of 100. They are tiny, thin, and very delicate. We'll need 8-10 per flight.
  • Solar panel tabbing wire (for soldering the panels in series)
  • 36 AWG magnet wire for antenna. The minimum I could buy is 3193 feet!
  • Fishing line for tether
  • TMP36 Temp sensors
  • Schottke Diodes (they came in a pack of 50. I bought SMT chips - I'm not sure if/how I'll wire them yet)
  • SMA Dummy load for testing
You'll also need basic Arduino programming/wiring components (micro USB cable, breadboard, jumpers, wire, etc.). And SMA adapters (mated to whatever End Launch Connectors you get) to plug into a 20m antenna for testing. I also bought a cheap high accuracy scale - http://a.co/8fD1Fnu

I'm still not sure how I'm going to put everything together on the payload. My current thinking is to mount on a small sheet of coroplast or styrofoam. I just need to balance it so the panels face up.

I'd hate for you to get too far along on this if my plan isn't a solid one, but I should know in a week or so if it's going to work. If you want, you could do an APRS version instead of, or in addition to, WSPR. You could also do JT9 or JT65 by changing just a couple variables.

Jared


On Tue, Jun 6, 2017 at 7:46 PM, <ag1t@...> wrote:
Jared,
 
  If you don't mind, I would like to clone your efforts.  If you would let me know where you purchase your equipment from, I will duplicate your setup and try working the code with you.  That way we can swap notes, etc.
 
  I hope to better my coding skills as well.  Plus, I could use my set of hardware to do temperature testing etc. against when you feel we are ready for it.
 
  Gary


Josh Jensen
 

Jared,

Just a couple things. You mentioned that you need a micro USB cable for programming. I don't know if they've changed the FTDI breakout board or not, but the one I have has a mini USB.

I mentioned earlier that I would take one of my pro minis into work and weigh it. It looks like the one I have left has some screw terminals soldered onto it. So I won't be able to weigh it. But you can probably handle that yourself now that you have parts in hand.

Speaking of my pro mini with screw terminals, how are you prototyping? Connecting the pro mini to the breadboard, or using an uno? You could borrow mine if you want for prototyping. It is a 5V version though. 

Depending on where you come in for weight, you might want to consider pulling unnecessary components off the arduino. You can get by without the reset button and the LED along with its resistor. It won't be a lot of weight savings, but when you're talking grams it can all add up. I couldn't remember if I mentioned it or not. 

Josh

On Jun 6, 2017 10:29 PM, "Jared Smith" <jared@...> wrote:
Gary -

I'd be happy to have you duplicate (or, better yet, improve upon) what I'm doing. If others are interested, it would make sense to combine orders to save on shipping. I'd be happy to coordinate this if others want to give it a go.

Most of the links to what I've purchased are in my Notes document - https://docs.google.com/document/d/1Es1rbg2a9rPM2AEG23-Rvfko8uyDNknSzF_th0O7MnU/edit?usp=sharing

You'd need to purchase the following:
  • Arduino Pro Mini ($10 - be sure to get the Arduino version, not a clone)
  • FTDI breakout module ($10 - only need 1 for programming)
  • Si5351A Clock Generator with TCXO ($15 plus $4 for their SMA End Launch Connectors)
  • GPS (~$25 plus shipping from the UK)
  • Supercapacitors ($4.81 each - need 2 per flight)
I have extras of most everything else you'd need and am happy to share:
  • Solar panels - I bought a pack of 100. They are tiny, thin, and very delicate. We'll need 8-10 per flight.
  • Solar panel tabbing wire (for soldering the panels in series)
  • 36 AWG magnet wire for antenna. The minimum I could buy is 3193 feet!
  • Fishing line for tether
  • TMP36 Temp sensors
  • Schottke Diodes (they came in a pack of 50. I bought SMT chips - I'm not sure if/how I'll wire them yet)
  • SMA Dummy load for testing
You'll also need basic Arduino programming/wiring components (micro USB cable, breadboard, jumpers, wire, etc.). And SMA adapters (mated to whatever End Launch Connectors you get) to plug into a 20m antenna for testing. I also bought a cheap high accuracy scale - http://a.co/8fD1Fnu

I'm still not sure how I'm going to put everything together on the payload. My current thinking is to mount on a small sheet of coroplast or styrofoam. I just need to balance it so the panels face up.

I'd hate for you to get too far along on this if my plan isn't a solid one, but I should know in a week or so if it's going to work. If you want, you could do an APRS version instead of, or in addition to, WSPR. You could also do JT9 or JT65 by changing just a couple variables.

Jared


On Tue, Jun 6, 2017 at 7:46 PM, <ag1t@...> wrote:
Jared,
 
  If you don't mind, I would like to clone your efforts.  If you would let me know where you purchase your equipment from, I will duplicate your setup and try working the code with you.  That way we can swap notes, etc.
 
  I hope to better my coding skills as well.  Plus, I could use my set of hardware to do temperature testing etc. against when you feel we are ready for it.
 
  Gary


Jared Smith
 

You mentioned that you need a micro USB cable for programming. I don't know if they've changed the FTDI breakout board or not, but the one I have has a mini USB.

The one I got from Amazon is micro USB. It also has a jumper to change voltage between 5v and 3.3v. Sparkfun has a mini USB version (https://www.sparkfun.com/products/9873) and a micro USB version (https://www.sparkfun.com/products/13263).
 
Speaking of my pro mini with screw terminals, how are you prototyping? Connecting the pro mini to the breadboard, or using an uno? You could borrow mine if you want for prototyping. It is a 5V version though. 

I'm using a breadboard for prototyping. I also have an Uno, but the voltage difference would complicate things.
 
Depending on where you come in for weight, you might want to consider pulling unnecessary components off the arduino. You can get by without the reset button and the LED along with its resistor. It won't be a lot of weight savings, but when you're talking grams it can all add up. I couldn't remember if I mentioned it or not. 

Yes, I may do this. I'm using the onboard LED to indicate status (lit if there's a GPS lock and flashing while transmitting), but that won't be necessary at 40,000 feet. :-)

The biggest weight savings would be in going with smaller supercapacitors. Going from 5F to 3.3F would save 1.2 grams. But having two in series to make 5.4 volts also cuts the capacitance in half. I'm going to test a lot to see how much of a difference it makes, but think I'll probably go with the smaller ones.

The Si5351A Clock Generator board is also rather heavy - I think ~4 grams. It has voltage switching/regulation and 2 extra outputs that aren't necessary. I'm going to look into another option or maybe trying to design a small custom breakout board with only one output. That would save around 2 grams.

Thanks!

Jared