Another PCB design gets shipped off to China for manufacture!
This is a tiny balloon computer. Without battery or GPS, it weighs less than 40 grams. It can transmit RTTY or CW at 25 mW on the ham 2M and 70cm bands, and will last up to 16 hours on a single AA.
This board will be Arduino compatible, and the primary goal will be to support White Star‘s superpressure balloon experiments. A superpressure balloon maintains some pressurization above ambient in order to maintain altitude. In order to figure out how to design the balloon envelopes, and to verify our math, we need to know what’s going on inside the balloon. It’s difficult to pierce the balloon without generating leaks. The ideal solution is to place a second balloon computer inside. Both will transmit pressure to the ground, and we’ll be able to compare pressure inside the balloon to ambient pressure for model verification. The pressure sensor can sense a change as small as 4×10-4 PSI, so this should work.
This is my first attempt at real RF design. Fortunately, operating within the ham radio bands means I don’t have to worry too much about spurious transmissions or leaky harmonics.