Transforming MMR-70 in to temperature sensing DAN - Data Acquisition Node.
Back and front (or front and back?) RFM12bs modified to provide analogue RSSI output. AA switch turns on Always Active mode, but in this case it is better to connect DAN to an external 3V power supply as CR2032 is for Power Saving mode only. Actually, in Power Saving mode this DAN draws less than 8 uA. When it wakes up for data measurement and transmission it can draw up to 14 mA, but because it happens only once a minute and takes only few milliseconds CR2032 fully restores before next session. On start up voltage goes down to 2.8V but it is back to 3.0V in about twenty minutes.
Top view - BMP180 sensor and RFM12bs antenna socket. Round border - standard film canister to which this frankenstein assembly perfectly fits into: