DFRobot Gravity Analog TDS Sensor Meter for Arduino - Waterproof Probe, 0-1000ppm

The sensor is directly compatible with any microcontroller featuring an analog-to-digital converter (ADC) and operating at 3.3V or 5V logic levels. This includes Arduino Uno, Mega, Nano; ESP32 and ESP8266 development boards; Raspberry Pi (with an external ADC); and most PLC analog input modules. Simply connect the module's analog output pin to an ADC input pin on your controller.

The sensor outputs a voltage linearly proportional to TDS. You must first calibrate the sensor using a standard solution. The general formula in code is: TDS (ppm) = k * ADC_Value, where 'k' is a calibration coefficient derived from a known TDS standard. DFRobot provides sample Arduino libraries and code that handle this linearization and temperature compensation, simplifying the integration process.

Yes, the probe is designed with a waterproof housing suitable for long-term immersion in water. The use of an AC excitation source prevents rapid degradation of the electrodes due to DC polarization. For optimal long-term stability, periodic calibration is recommended, and the probe should be cleaned if biological fouling or mineral scaling is observed.

The AC (alternating current) excitation applies a reversing voltage to the probe's electrodes. This prevents the buildup of ions on the electrode surfaces—a phenomenon known as polarization—which would cause measurement drift and reduce sensor lifespan. This design ensures more stable and repeatable conductivity readings over extended periods compared to DC-excited sensors.