Design of Electrical Conductivity Instrument Based on Pulse-Width Adjustable Bi-directional Pulsed Voltage

Based on the improved bi-directional pulsed voltage method, a kind of new on-line electrical conductivity instrument was designed. By using the bi-directional pulse-width adjustable voltage as excitation source, the instrument can adjust width of pulsed voltage automatically according to different solution to eliminate capacitance effect and weak polarization effect. Instrument's hardware is composed of bi-directional pulsed voltage generating circuit, range switching circuit, wave conversion circuit and A/D conversion circuit. The application software develops with LabVIEW and C51 assembler language. The instrument can realize many functions, such as system calibration, data processing, display and storage, and its relative error is less than 2.8%.