Gravity: Analog TDS Sensor/Meter
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Gravity: Analog TDS Sensor/Meter - Water quality measurement

Gravity : TDS (Total Dissolved Solid) sensor

  • Cleanliness of water
  • Analog output : 0 to 2.3V
  • 0 to 1000ppm
  • Power supply : 3.3 – 5V
€14.28 (tax incl.) €11.80 (tax excl.)
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Use a TDS sensor to measure the water conductivity and evaluates its purity

This probe measures the purity of the water by making a TDS (Total Dissolved Solids) reading, see below. The value of TDS is an immediate reflection of the purity of the water and therefore also of its cleanliness. This probe and its signal transmitter board can read the TDS between 0 and 1000ppm.

This type of probe can be used to measure in domestic water, hydroponics and other measures of water quality. It is a very common measuring instrument, its price is affordable and very easy to use.

On the other hand, this type of measuring device is generally not able to communicate the captured data, these being simply displayed on an LCD screen. A communicating device costs a real fortune.

Our friends of DFRobot had the good idea to accompany this product with an analog interface thus making it possible to produce an analog output voltage between 0 and 2.3V in relation to the measured TDS (between 0 and 1000ppm).

This information can therefore be read by a microcontroller having an analog input tolerating at least 3V. As a result, this product can be used with Arduino Uno boards (5) and other 3.3V logic microcontrollers.

Thanks to this product, it becomes possible to create your own measurement, collection and data transmission system. It is even possible to use this information to automate water treatment cycles.

The probe is composed of a fork element circulating an alternating current between the points of the fork making it possible to take the reading. The use of an alternating current on the fork avoids the problem of polarization of the probe (loss of electron, ionization and electrolysis) thus improving the lifetime of the probe. The use of an AC voltage also improves the stability of the output signal.

The TDS measuring probe is waterproof and can be immersed in water for long periods of measurement. However, the signal transmitter board is not waterproof (so be careful).


  1. The probe can not be used in water above 55 degrees centigrade.
  2. The probe can not be left too close to the edge of the container, otherwise it will affect the reading.
  3. The head and the cable of the probe are waterproof, but not the connector and the signal transmitter

TDS! What about it?!?!

TDS (Total Dissolved Solids) indicates that how many milligrams of soluble solids dissolved in one liter of water. The measure is expressed in PPM (part per million).

In general, the higher the TDS value, the more soluble solids dissolved in water, and the less clean the water is.

Therefore, the TDS value can be used as one of the references for reflecting the cleanliness of water.

See TDS diagram in the product pictures.


  • Supply voltage: 3.3 to 5.5V
  • Output voltage: 0 to 2.3V, analog voltage.
  • TDS Measure range: 0 ~ 1000ppm
  • Compatible with 5V or 3.3V microcontroller
  • AC Excitation Source: effectively prevent probe from polarization
  • Waterproof Probe

Easy to Use: Arduino compatible, simple connection, plug and play without soldering

Technical details

Signal Transmitter Board

  • Input Voltage: 3.3 ~ 5.5V
  • Output Voltage: 0 ~ 2.3V
  • Working Current: 3 ~ 6mA
  • TDS Measurement Range: 0 ~ 1000ppm
  • TDS Measurement Accuracy: ± 10% F.S. (25 ℃)
  • Module Size: 42 * 32mm
  • Module Interface: PH2.0-3P (Gravity)
  • Electrode Interface: XH2.54-2P

TDS probe

  • Number of Needle: 2
  • Total Length: 83cm
  • Connection Interface: XH2.54-2P
  • Waterproof Probe


Data sheet