NearSys introduces the BalloonSat Extreme. This is one of the largest BalloonSat flight computers. At its heart is the BASIC Stamp 2 (the BS2pe is recommended), so it is powerful and easy to program.
The flight computer has an eight-channel analog port with 12-bits of resolution for sensors like weather stations. There is a five-channel digital port with connections directly to the BS2 for sensors like Geiger counters. Unlike other BalloonSat flight computers, the BalloonSat Extreme has a GPS Port to allow your BalloonSat to monitor and record GPS reports (like altitude and time). The flight computer can operate three cameras. The cameras can ones with modified shutter buttons or be Canon cameras running the CHDK USB remote program. The flight computer can also control three servos. The servos have a seperate power supply to prevent a bad servo from draining the main power supply.
Part of the BalloonSat Extreme kit is its Control Panel, a seperate printed circuit board. The Control Panel allows you to power up the flight computer without opening the BalloonSat. Two LEDs indicate power is available for the flight computer and the servos. Finally, there is a Commit Pin that allows the BalloonSat to be powered up long before launch. When ready for lift-off, pull the Commit Pin and the flight computer will begin recording data.
The entire kit is only $48. Check it out and its directions and sample code at, http://nearsys.com/catalog/balloonsat/extreme.htm