Smallest size electronics payload ever!?

[FROB]

Does anyone know what the maximum functioning altitude is for the PicoAlt altimeters? I was discussing putting an altimeter on some high-altitude balloons in another thread, that reach maximum altitudes of about 130,000 ft...

The specs are listed in the manuals which you can download on their website: https://www.picoalt.com/: 40,000'
Most barometric altimeters top out between 25k and 50k feet.

Above that, air pressure is so low with typical pressure sensors your pressure reading is meaningless anyways because the errors are bigger than the theoretical result.

At 100,000 the air pressure is 1/1000 of sea level, and 130k' your getting into high vacuum territory.
Even the very best aviation altimeters will have trouble producing a meaningful measurement at that level.
Which makes it all the more amazing that you can get any kind of balloons to float that high, with a payload to boot!
I'd suggest going with GPS.

 

[Reinhard]

On the quarter from left to right is my barometric sensor, the CPU, the 3-axis accelerometer (g-switch), and finally the dual 8-Amp mosfet for pyro outputs.
(snip)
Cool, eh?

They look like they're "funny" to solder. Will you reflow them? The 3-axis accelerometer makes me wonder. What is the maximum range of the device? The ones that I have read about can only handle comparable low accelerations (typ. 6g or lower).

Reinhard

 

[FROB]

They look like they're "funny" to solder. Will you reflow them? The 3-axis accelerometer makes me wonder. What is the maximum range of the device? The ones that I have read about can only handle comparable low accelerations (typ. 6g or lower).

Reinhard

Thats correct.
6/8/10g is more than enough to use as a simple G-switch to trigger timers, but not for integrating acceleration and trying to detect apogee from that, unless its a very low-G rocket configuration you have, and you are certain it wont go over the device range limit in acceleration.

 

[Adrian A]

... 25k and 50k feet.

Above that, air pressure is so low with typical pressure sensors your pressure reading is meaningless anyways because the errors are bigger than the theoretical result.

At 100,000 the air pressure is 1/1000 of sea level...

At 100 kft, the air pressure is about 1% (not 0.1%) that of sea level. Above about 30,000 feet the relationship between temperature and altitude changes, which means that you need an entirely different formula for converting pressure to altitude than you do at low altitude. The only altimeter that I know of that does that, does it by recording the pressure during the flight and converts it to altitude it after the flight.

An altimeter with a 13-bit A/D and a good baro sensor will measure about 400 feet per count at that altitude, and a well-calibrated sensor will have less than 1% inaccuracy in slope, so it's not quite meaningless. I agree with the overall point, though, that you'd be much better off with GPS if you're in the neighborhood of 100,000 feet.

 

[tbzep]

24mm. A BT-50 sized rocket is probably the smallest I'd ever care to fly a payload with. If price increases as size decreases, it would likely be a happy medium between size and price.

 

[Graham Orr]

38 mm is a good size for research purposes.

I designed some rockets a few years back that flew (in a 38mm bay):

HiDef Split Vision Video / telemetry
6-axis IMU
RDAS / telemetry
18 Embedded Strain Gauges
Signal Conditioning Board
4 Embedded Thermistors
Nose Pitot Tube / Ducer
Single Recovery (RDAS)
9V Lithium Power w/ 5V reg for video

 

[bob jablonski]

24mm as that would fit in the Starlight Flash 24 payload section. Plus you can send it up on some composit motors
Mr. Bob
Starlight Freak

 

[Chrisn]

There is no set diameter, it depends on the altitude, motor/motors being used or need to record data from the flight

 

[Ford Prefect]

I voted 29 cause I don't have the manual dexterity required to us such small itti biiti little things as 13mm electronics. Also I only plan to use alts to do dual deploy soooo..

CJ

 

[Micromeister]

Ok here's a little teaser for the MMX crowd:

i just got the last of the component samples that i was waiting on, for the smallest device i want to do.
I couldn't resist lining up all the key parts on top of a quarter with a ruler to take a picture and show you just how small this can go.
The first picture i tried to include my thumb for scale but hard to hold the camera with one hand and push the trigger so its a little fuzzy.

To the left of the quarter is typical "miniature" pressure sensor
and on the right is a precision digital gyroscope chip i will use later.

On the quarter from left to right is my barometric sensor, the CPU, the 3-axis accelerometer (g-switch), and finally the dual 8-Amp mosfet for pyro outputs.
of course, there's a few other little parts needed, but those will mostly be R's & C's only 1/2mm wide.
The largest part, the pressure sensor, is 5x5mm. the whole board can therefore be as little as 6mm wide and if so, it will need to be about an inch long. I have decided on using 2 tiny watch batteries for that in a unusual mounting arrangement that will allow the whole thing to still fit in a 1/4" tube, adding only another 1/2" in length.
That will still fire low-current ematches if you add a small supercap, which would add another 1" in length and increase the diameter to a whopping 8mm.
Without the supercap it should weight on the order of 1 gram

Cool, eh?

Now i can't wait to get the board design finished and assembled.

You BetCha! That is Way Cool! Great Job finding micro minature parts!!!!

Now if we could only find a couple value supercaps that'll fit in the .255" ID tube
Are you planning on offering these for sale at some point?

 

[FROB]

You BetCha! That is Way Cool! Great Job finding micro minature parts!!!!

Now if we could only find a couple value supercaps that'll fit in the .255" ID tube
Are you planning on offering these for sale at some point?

Yes, eventually, but right now i'm focussing on some other MUCH more complex designs- like the HD camera, and other cool things.

I tested the 8mm dia 3F supercap. Amazingly, after a 1 minute charge, it can light a xmass tree mini-light for over 30 seconds continuously! there is a smaller 6mm dia one i found- i will get a sample of that and try it, but judging from this one , it should be more than enough to fire some low-current ematches.

 

[Micromeister]

Yes, eventually, but right now i'm focussing on some other MUCH more complex designs- like the HD camera, and other cool things.

I tested the 8mm dia 3F supercap. Amazingly, after a 1 minute charge, it can light a xmass tree mini-light for over 30 seconds continuously! there is a smaller 6mm dia one i found- i will get a sample of that and try it, but judging from this one , it should be more than enough to fire some low-current ematches.

If the 6mm dia supercap will light Quest Q2's it'll be a winner we Micro flyers generally can't or don't use e-matches
If you don't mind sharing: where did you find the 6mm supercaps? I've been looking for such an animal for the last couple years.
Thanks