Project Horus High altitude balloon project

Backup CW beacon

I put together a simple backup CW (morse code) beacon for future launches yesterday for total cost of only a few dollars.

The beacon is comprised of only a microcontroller, a $4 10mW 434mhz transmitter & a few passives. The beacon is a standalone device, and pips out a few bits of information about the payload, including the frequency and transmission mode for the primary telemetry, how long the beacon has been switched on for and a URL to the project web page.

Backup CW Beacon

Because of the simplicity of the transmitter, it has very poor thermal stability, and is very easily affected by objects touching it/in close proximity to it (affecting the loading of the crystal - it's very cheap!). It won't be of much use whilst the balloon is in the air, but if we lose the payload, this should help us find it once it's on the ground.

Backup CW beacon

Running on 2AA lithium batteries, run time should be close to a week when constantly transmitting, more if the duty cycle is lowered a bit.

Edit: I have uploaded both the schematic & board layout.