How to Use TDS SENSOR: Examples, Pinouts, and Specs

• A TDS (Total Dissolved Solids) sensor measures the concentration of dissolved solids in a liquid, typically water. It provides an indication of water purity and quality by detecting ions, salts, and other dissolved substances.
• Common applications include water quality monitoring, aquariums, hydroponics, and industrial water treatment systems.

• Input Voltage: 3.3V - 5.0V DC
• Output Voltage: 0 - 2.3V DC (analog signal)
• Measurement Range: 0 - 1000 ppm (parts per million)
• Accuracy: ±10% (at 25°C)
• Temperature Range: 0°C - 60°C
• Interface: Analog output
• Probe Material: Stainless steel (corrosion-resistant)
• Cable Length: Typically 1 meter

1. Connect the Sensor:

   • Connect the VCC pin to a 3.3V or 5.0V power source.
   • Connect the GND pin to the ground of the circuit.
   • Connect the AOUT pin to an analog input pin of a microcontroller (e.g., Arduino UNO).

2. Calibrate the Sensor:

   • Use a known TDS solution (e.g., 342 ppm calibration solution) to calibrate the sensor.
   • Adjust the calibration potentiometer on the sensor module until the output matches the known TDS value.

3. Place the Probe:

   • Submerge the stainless steel probe in the liquid to be tested. Ensure the probe is fully immersed but avoid submerging the entire module.

4. Read the Output:

   • The sensor outputs an analog voltage proportional to the TDS value. Use an ADC (Analog-to-Digital Converter) to read the signal.

• Avoid Air Bubbles: Ensure no air bubbles are trapped around the probe, as this can affect accuracy.
• Temperature Compensation: TDS readings are temperature-dependent. Use a temperature sensor for compensation if precise measurements are required.
• Cleaning: Clean the probe regularly with distilled water to prevent residue buildup.
• Avoid Corrosion: Do not use the sensor in highly corrosive liquids or at temperatures beyond its specified range.

// TDS Sensor Example Code for Arduino UNO
// Reads the analog output of the TDS sensor and converts it to ppm

const int TDS_PIN = A0; // Analog pin connected to the TDS sensor
float voltage, tdsValue;

void setup() {
  Serial.begin(9600); // Initialize serial communication
  pinMode(TDS_PIN, INPUT); // Set TDS pin as input
}

void loop() {
  int sensorValue = analogRead(TDS_PIN); // Read analog value from sensor
  voltage = sensorValue * (5.0 / 1023.0); // Convert to voltage (5V reference)
  
  // Convert voltage to TDS value (ppm)
  tdsValue = (voltage * 1000) / 2.3; // Assuming 2.3V corresponds to 1000 ppm
  
  // Print the TDS value to the Serial Monitor
  Serial.print("TDS Value: ");
  Serial.print(tdsValue);
  Serial.println(" ppm");
  
  delay(1000); // Wait 1 second before next reading
}

1. No Output or Incorrect Readings:

   • Solution: Check the wiring and ensure the sensor is powered correctly. Verify the probe is fully submerged in the liquid.

2. Fluctuating Readings:

   • Solution: Ensure the liquid is still and free of air bubbles. Use a stable power supply to avoid noise.

3. Corrosion or Residue on the Probe:

   • Solution: Clean the probe with distilled water and a soft cloth. Avoid using abrasive materials.

4. Inconsistent Calibration:

   • Solution: Use a fresh calibration solution and ensure the potentiometer is adjusted carefully.

• Can the TDS sensor measure salinity?
  Yes, TDS sensors can indirectly measure salinity, as dissolved salts contribute to the TDS value.

• Is the sensor waterproof?
  Only the probe is waterproof. The module should not be exposed to water.

• Can I use the sensor for hot liquids?
  No, the sensor is designed for liquids within the 0°C - 60°C range. Exceeding this range may damage the probe.

• How often should I calibrate the sensor?
  Calibration frequency depends on usage. For critical applications, calibrate before each use. For general use, calibrate monthly.