The 3.3$ Altimeter

I wanted an altimeter which is so cheap, that you can give it away to kids during launches.
Model rocketry is quite uncommon in Germany, and where are happy about every kid that shows up at a launch.
While we regularly give away model rocket motors, altimeters are normally too expensive.

So my Altimeter is designed to minimize costs. The full altimeter including battery costs 3.3$.
It is based on an Arduino pro mini 3.3V 8Mhz and a BMP180.

Costs:
Arduino pro mini 3.3V 8Mhz 1.78 $
BMP180 1.05 $
Battery Holder 0.12 $
Battery CR2032 0.16 $
Wires / Solder / Shrinktube 0.19 $
Sum 3.30 $

The altimeter has a kalman filter with 64 Hz measurement rate.
It measures the maximum altitude, and when you restart the altimeter, it will blink out the last maximum altitude which is saved in the eeprom.
It consumes around 4mA/h during operation, with the 200mAh of the CR2032 that should last several launches.
To save power the altimeter powers down after apogee.

I am still in the development process.
I have to find the best kalman gain.
For this I have also designed a version which logs all pressure readings to a micro sd card, which cost only 33 cent more for the sd socket.

The weight is 8g (0.3oz) including the battery.

Nice concept!

This I'd an awesome idea

Great concept.

Looks kinda familiar :wink:

Where do you get CR2032 batteries for 16¢ ?

JD

JDcluster said:

Where do you get CR2032 batteries for 16¢ ?

JD

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eBay is your friend. E.g. 5 pc. for $0.76 including free shipping!

Very nice.

Leo said:

eBay is your friend. E.g. 5 pc. for $0.76 including free shipping!

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Retail stores wanted 25-30 dollars for a single battery for my camera. I found a pack of 3 batteries for 5 dollars on eBay.

Great, will you open source the code?

JERRYR708 said:

Retail stores wanted 25-30 dollars for a single battery for my camera. I found a pack of 3 batteries for 5 dollars on eBay.

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Look here...

This is an excellent idea. As far as batteries go, if one can find name brand (not counterfeit) for cheap, go for it. I've bought a lot of Chinese specials and the "shelf life" is just a few months in some cases. But I'd be willing to risk it like Jerry if I could get three batteries for $5.00 as opposed to spending $90.00. Kurt

Excellent work Leo I know some people that do launches for kid and I am sure that they would be interested. Are you planning on selling those?
Arduino board are so cheap now ... building one myself cost me more it is cheaper than what I pay for the microcontroller whn I build my altimeter!!!

Excellent idea.

bdureau said:

Excellent work Leo I know some people that do launches for kid and I am sure that they would be interested. Are you planning on selling those?
Arduino board are so cheap now ... building one myself cost me more it is cheaper than what I pay for the microcontroller whn I build my altimeter!!!

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That's not from me, Thomas just copied my setup idea which he forgot to mention in his post

Oh, sorry Leo, I missed this in the English version. Well, Leos altimeter, which is much more advanced, was a inspiration for this project:
https://www.altduino.de/

Beside that both altimeters use the arduino pro mini, there are completely independent.

I am going to release the code and a tutorial for the hardware, when I have finished the testing

I am also trying out some recording features, for the eeprom.
With 1024 byte one should be able to log a full flight at a reduced rate 20Hz to Apogee, 5 Hz after Apogee and saving only differential altitude values.

thomas said:

Oh, sorry Leo, I missed this in the English version. Well, Leos altimeter, which is much more advanced, was a inspiration for this project:
https://www.altduino.de/

Beside that both altimeters use the arduino pro mini, there are completely independent.

I am going to release the code and a tutorial for the hardware, when I have finished the testing

I am also trying out some recording features, for the eeprom.
With 1024 byte one should be able to log a full flight at a reduced rate 20Hz to Apogee, 5 Hz after Apogee and saving only differential altitude values.

Click to expand...

Really looking forward to that.

I got a brick of 200 2032's a couple of years ago to use in my daughters wedding. They were just taped to LED's for mood lighting. Anyway I think I got them for $25 shipped from china thru Aliexpress.

Really cool idea!