Some Pictures of the circuits

I have taken some pictures of what we have done. Below is a picture of the balloon exploder circuit that will be on the first test launch. Its primary purpose is to wait a designated amount of time, the set off a solar ignitor that will not in fact pop any balloons, but it will burn through the line connecting the parachute and the balloon. 

Below is the data logger I have created. On board is the atmega 328, a 12 volt and 5 volt voltage regulator, a 12v one sided op-amp, usb break out board, dual axis accelerometer, a thermistor, and a barometer. 

Below is the trackuino. This is designed to get the gps signal and send it over the aprs network. It can also transmit temperature and other data aswell. More about it at http://code.google.com/p/trackuino/

This is a photo from inside the Styrofoam box. I had taped down some wires on the balloon exploder circuit (on the top) since I only used a protoboard because this is temporary and only intended for the test flight. We have the data logger on the right and on the left a gps tracker. The trackuino has not yet been tested, although once its working the other gps tracker will probably remain for redundancy.

Here is a shot at another angle. As you can see we have dowel glued in to hold the circuits and other pieces into place while in flight.

Here's a picture of the closed box. We have the radio transmitter sticking out the top and also the wires for the balloon exploder circuit. 

 And another picture of the payload. The total measured weight is 960 grams.

Some Test Data

For the last couple of weeks I have been doing some fine tuning and some testing. First of all, I have been testing the data logger and and now have some calibration data for the barometer and the accelerometer. I have also found out that the thermistor we currently have outputs a negative voltage for negative numbers and a positive voltage for positive numbers. The arduino does not recognize negative voltages. We could have run the thermistor through an opamp to shift the voltage, but since I'm running out of room on my board, it is just easier to order a different one that does only positive voltage. Once this comes in, I will put some test data of the temperature up. I have also done some testing of the balloon exploder circuit. We plan to have a few smaller balloons for the first test flight. It will be easier to cut the line than to have a number of balloon exploders, so I needed to test to see if the solar ignitors will burn through the nylon line. I did a test with simply a solar ignitor connected to 18v and another test with the whole exploder circuit and both tests were successful.

The barometer calibration data is at the following link:
https://docs.google.com/spreadsheet/ccc?key=0AqH-Vyu_xTSKdGFBam9sbFFIbEJUMDRRRER1RG8tcnc
And some test data is at the following link:
https://docs.google.com/spreadsheet/ccc?key=0AqH-Vyu_xTSKdDN1S0EyOVJXRlZWdThxamR1NWpxUEE