A Low-Cost Digital Psychrometer and Humidity Controller

The digital psychrometer presented in this paper is a general type of humidity meter with an accuracy of ±1 percent with 8-bit resolution and the humidity controller has an accuracy of ±0.5 percent. It is optimized by using the fewest possible number of components in order to increase the reliability and to reduce the cost. The speed of operation of this circuit is on the order of 500 ns. This circuit is used for measurement and control of humidity in the temperature range of 0-31°C with an accuracy of ±1°C for temperature with 5-bit resolution and 1-kbyte memory space is used for storing humidity values. This circuit is provided with wide flexibility to change its measurement range according to the users' specifications. This circuit is used for measurement and control of humidity in cold-storage process applications, textile industrial applications, etc.