Abstract
A digital thermo-hygro controller was designed and fabricated using humidity (HIH-3610) and temperature
(LM-35) sensors connected to a programmable microcontroller 16F876 of PIC family. This unit was calibrated with
the standard Kestrel 4000 NV Weather Meter and psychrometer. It was tested for humidity and temperature
measurements in the Green Houses, Glass Houses, Textile Spinning Units, Agro-climatology and Cropphysiology
labs. Statistical analyses, like as T-test, standard deviation on the data obtained were performed to
compare its performance with the standard thermo-hygrometers. The error in its performance was only ~5% in
humidity and ~2% in temperature measurements. It gave prompt response directly and had low power
consumption. Thus, it can be rated as a reliable and an economical three times cheaper replacement of the
currently in use expensive imported devices. It is useful for agricultural and industrial sector and where a predecided
humidity and temperature levels are needed to be monitored.
