Simulation Studies on a New Intelligent Scheme for Relative Humidity and Temperature Measurement Using Thermistors in 555 Timer Circuit

This paper presents a novel and cheap electronic version of wet and dry temperature hygrometer The instrument is centered around a 555 timer, operated in astable multivibrator mode. Two thermistors with negative temperature coefficients (NTC) serve as the two timing resistors of the multivibrator. These thermistors are used to sense the dry and wet temperatures. The durations of the ‘HIGH’ and ‘LOW’ levels of the multivibrator output are detected and these values are used to predict the relative humidity and ambient temperature by an appropriately trained Artificial Neural Network (ANN). The performance of the arrangement has been evaluated by numerical simulation studies using thermistor data from manufacturer’s table. Significantly good results have been obtained.