Code Repository - github.com/philcrump/UKHASnet_nodes
I've built the Synchronous RFM69HW Library for the Arduino framework that I use with the Nodes.
Following James' Simple Stripboard Design for the London Hackspace Workshop, I began to use this as a base for the AVR-based nodes.
A 1W solar panel provides continuous power for the node, whilst a 4Ah LiPo battery gives a large reserve capacity to maintain the node through the nights and usual bad weather.
These nodes are powered off 3x AA batteries with a 3.3V LDO (MCP1700). These nodes are in sleep-mode between transmissions and so do not repeat, but should last ~3 months on one set of batteries.