Vario version 3

Learning from the experience gained from the previous versions (1 and 2), we have arrived at the present solution, a design which we consider actually meets the implied performance goals of this project: i.e. sensitive indication of lift, proportional signal values, sufficient radio range and negligible mass.

The major components:

1) The pressure sensor is once again the reliable Bosch BMP085.

2) For choice of µC board we are back with the Pro Mini 3.3v/8MHz. Simply because it is the smallest and lightest of all the commercially available Arduino variants.

3) The Tx/Rx system comprise a pair of the powerful XBee-PRO 900 MHz modules. This system has a very convenient basic interface in default mode. Most significantly, it also has a nominal (claimed) transmission range of several kilometers!

4) A synthesized speech chip was added to the receiver circuit in order to provide experimental altitude feedback.