Abstract: A moisture detection unit for sensing the moisture content of tobacco is disclosed. A capacitor sensor forming part of a C.R. network is arranged so that the tobacco is passed through or near the sensor. The capacitance of the sensor is proportional to the moisture content of the tobacco, and this capacitance determines the frequency derived by an oscillator to which the C.R. network is connected. The output frequency is inversely proportional to the sensor capacitance. A frequency to voltage converter derives a voltage proportional to the frequency and this voltage signal is then passed through an inverter. The inverter has an off-set which compensates for the standing capacitance of the sensor, to derive an output voltage which is proportional to the moisture content of the tobacco. This voltage can then be used to drive a digital read-out.