Development of a Digital Conductivity Meter with Frequency Response for Remote Monitoring
José Alberto Fracassi da Silva, Marcelo Freire de Barros, Claudimir Lúcio do Lago · Instrumentation Science & Technology · 1998
A simple and inexpensive conductivity meter with frequency response is shown. Good linearity is achieved up to 10 mS but, by using a special function, given from a theoretical standpoint, precision measurements can be done up to 100 mS. To allow temperature compensation, another similar circuit is used, where the conductivity cell is replaced by a negative temperature coefficient resistor (NTC). The intrinsic non-linearity of this component was not enough to limit its use as a temperature sensor within a several-degrees range. The good signal-to-noise ratio obtained for long distances, the integrative response in pulsecounter mode, and the independence between frequency and supply voltage make this equipment specially suitable for field monitoring.