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TDS Module ESK-TDS-66F0185

US$ 18.90
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TDS (Total Dissolved Solids) is a measure of the combined total of organic and inorganic substances contained in water. It can be a general indicator of water quality. The unit of TDS measurement is ppm or milligrams per liter (mg/L). The larger the TDS value, the more dissolved substances in water.

In many consumer products, the TDS value is calculated by measuring the conductivity of water (in uS/cm), which is roughly 1 ppm TDS = 2uS/cm. Using parallel cylindrical electrodes with fixed distance as the measuring probe, the probe is placed in water and a voltage is applied between the two electrodes to measure the conductivity.

Factors affecting the accuracy of TDS measurement include water temperature, flow rate, etc. In general, the standard measurement temperature is 25°C. For each 1°C increment, the TDS value increases by about 2%. When measuring TDS, the water temperature is usually measured together for temperature compensation.

The Holtek TDS Workshop platform integrates the rich functions of TDS measurement, temperature measurement, button input, display, communication etc. You can complete the configurations and generate MCU codes in several steps. The TDS platform also has a calibration monitoring window to calibrate the device and monitor the measured TDS value continuously. The measurement records can be exported to an excel file.

Holtek provides four evaluation boards to work with the TDS platform:

  1. TDS Module ESK-TDS-66F0176: the measurement module, use HT66F0176 MCU, with a TDS sensor probe (TDS-37).
  2. TDS Module ESK-TDS-66F0185: the measurement module, use HT66F0185 MCU, with a TDS sensor probe (TDS-37).
  3. TDS Module ESK-TDS-66F019: the measurement module, use HT66F019 MCU, with a TDS sensor probe (TDS-37).
  4. TDS Display Board ESK-TDS-100: the motherboard, can connect to any of the three TDS modules.

TDS Module ESK-TDS-66F0185 supports both single-channel and dual-channel measurement of TDS and temperature. When using single-channel measurement, the LCD and button functions are available; you may use the LCD and button on the TDS Display Board (ESK-TDS-100) for verification. Either the UART or IIC can be used for communication.

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  1. Input voltage: 3.3V – 5V
  2. TDS measuring range: 0 – 2000 ppm
  3. TDS accuracy: ±5% F.S.
  4. Temperature measuring range: 0 - 99°C; (0 - 60°C if you use TDS-37 probe, according to the TDS-37 specification)
  5. Temperature accuracy: ±1%
  6. TDS sensor probe connector: XH2.5-2P (2.5mm)

Product Information

TDS Module Board

  1. Dimension: 34 x 32 x 16(mm)
  2. Weight: 8.4g

TDS sensor probe (TDS-37)

  1. Length: 537.5 mm (not including the electrode)
  2. Weight: 13.5g
  3. Connector: XH2.5-2P x 2 (blue wire for TDS, red wire for NTC temperature sensor)
  4. Electrode: 2

Packing List

  • TDS module board x 1
  • TDS sensor probe (TDS-37) x 1


TDS Workshop software: Holtek TDS Workshop
MCU: Holtek HT66F0185, A/D Flash MCU with EEPROM

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