Abstract: A moisture sensing apparatus includes an oscillator for supplying an AC signal to a driven ring of a sensor having a pad inside the ring, and a ground plate around the ring. An amplifier forms part of a temperature-compensated, precision rectifier, and is connected to the pad. A first diode connected to the output of the amplifier in a feedback loop of the amplifier, where the amplifier nullifies temperature variation effects upon the diode, and supplies a rectified signal which is a function of moisture content of material in contact with the sensor. A second diodes is connected between the amplifier output and other input of the amplifier. The sensor has a rounded configuration to avoid electrostatic field fringing effects, and a passive impedance with both resistive and capacitive members is connected in parallel with the sensor to provide a functional baseline for the rectified signal.

Abstract: In a monitoring system for a wood drying kiln having a housing with an interior area for placement of a charge of wood for drying the charge of wood, the interior area having a floor, environment devices for adjusting heat and humidity in the interior area of the kiln, and a control unit for controlling the environment devices, the improvement is a support in the interior area for supporting a representative sample of the charge of wood, a sensor mounted to the support for sensing the weight of the sample which is a function of moisture content in the sample and a proportioning mechanism connected between the sensor and the sample for suspending the sample and for applying a proportioned force resulting from the weight of the sample to the sensor. The sensor is connected to the control unit for generating a signal which is proportional to the weight, and thus, to the moisture content of the sample.