Arduino Pro Mini (3.3 V, 8 MHz) measuring outside temperature and humidity using a DHT21. Powered by 3 AA eneloops using (only) the on-board voltage regulator. Battery voltage is measured by internal ADC. Wifi connected by esp8266
Logging of the house temperature with raspberry and DS18B20 sensor.
Outside Temperature and Relative humidity in Brampton, Canada. DHT22 measures and solar powered ESP8266 uploads.