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Proceedings Paper

Design of precision measurement circuits for the relative humidity
Author(s): Yanpeng Wang; Guanwang Gao; Zhanyou Sha
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Paper Abstract

The two methods of the relative humidity measurement are introduced in this paper. The one is adopting transistor and operational amplifier to compose a logarithmic amplifier, by which to realize the linearization of exponent mode character curve of moisture-sensitive resistor. And using the positive temperature coefficient of the adjustable current source (+0.33%/°C) compensate the negative temperature coefficient of the thermistor (-0.36%/°C). Zero temperature drift is realized by the methods and the measurement accuracy reached ±2%. The two is adopting intelligent temperature/relative humidity sensor, which combined the multiple parameter sensor and transmitter, to realize the accurately measurement not only of the relative humidity, but also of the temperature and dew point. Through the 2-wires serial port the system can be connected to MCS-51 MCU. The accuracy of the relative humidity measurement is ±1.8%; the nonlinear error can be reduced to ±0.1% after software arithmetic compensation. The temperature range measured is -40~ + 123.8°C. The accuracy of dew point measurement is ‹±1°C

Paper Details

Date Published: 10 July 2009
PDF: 4 pages
Proc. SPIE 7490, PIAGENG 2009: Intelligent Information, Control, and Communication Technology for Agricultural Engineering, 74900F (10 July 2009); doi: 10.1117/12.836661
Show Author Affiliations
Yanpeng Wang, Hebei Univ. of Science and Technology (China)
Guanwang Gao, Hebei Univ. of Science and Technology (China)
Zhanyou Sha, Hebei Univ. of Science and Technology (China)


Published in SPIE Proceedings Vol. 7490:
PIAGENG 2009: Intelligent Information, Control, and Communication Technology for Agricultural Engineering
Honghua Tan; Qi Luo, Editor(s)

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