Humidity and dew point detector

摘要

A humidity detector using a ceramic sensor and a heater to periodically clean the sensor. The output of the sensor is sampled and held while the heater is on. When the detector is turned on, the heater is not started until the sensor has been sampled and held. The timer controlling this operation can be externally reset. When the ceramic sensor is temperature corrected, the humidity output indicates a dew point at a fixed temperature. By adjusting this fixed temperature dew point output according to a sensed temperature, the dew point can be detected.