RC-SPC1K Rain sensor from Radiocontrolli

Made from a thick-film technology, the RC-SPC1K sensor consists of measuring part (capacitive sensor) as  well as heating one. The sensor's characteristics feature capacity changes from 100 pF at zero humidity to over 550 pF at 100% humidity (relative change over 420%). The sensor has also a built-in NTC thermistor (nominal resistance 1 kΩ at 25°C) for temperature measurements. This  allows a monitoring of environmental temperature e.g. to protect the sensor from freezing.