Twin-probe controlled audio frequency signal system - indicates moisture and fertilizer content in soil samples using insulated conductor probes

摘要

The audio-frequency signal generating system is used to measure conductivity and dielectric properties of a liquid or liquid-containing material, esp. to determine moisture and fertilizer content of soil samples. Two probes are inserted into the material, the resistance and capacitance between the probes is measured, and audio-frequency signals are generated as a function of the measured values to indicate the properties being investigated. Pref. a reduction in capacitance with an increase in frequency corresponds to a low fertilizer content in moist soil. The insulated conductor probes (111, 114) are of similar dimensions and in the form of cylindrical rods with conical tips.