According to working principle of capacitive humidity sensor

capacitance value between two plates of the sensor changes linearly with change of dielectric constant

and grain moisture content affects dielectric constant.The instrument

uses chip CAV424 for capacitance measurement which is used to convert the capacitance value to DV value.The A/D module converts into digital quantity by system-on-chip microcontroller C8051F060 and then the grain moisture content can be calculated after data processing.The instrument displays measured value through LCD and the historical data automatically stored by the instrument is browsed

the measurement data is uploaded to the host computer real-time by RS—485 interface and remote measurement is realized.Due to a system-on-chip and special measurement IC in the instrument

the whole system has characters of simple circuit design

high detection precision

stable and reliable performance.