Circuit to Read Data from a Water Flow Sensor using Arduino

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So far, we had seen a lot of circuit for interfacing many sensors to arduino in my previous blogs. Here, we will see the circuit for interfacing a water flow sensor to arduino. This is a magnetic hall effect based sensor which has a pinwheel sensor to measure how much liquid has passed through it. I am using a water flow sensor purchased from rhydoLABZ.

Sensor has three wires. A red, a black and an yellow wire. Red wire is for giving power supply (5V) to the sensor. Black wire is the ground and yellow wire is for taking the hall effect pulse output from the sensor. Yellow wire is normally connected to the digital pin of arduino. By counting the pulses from the output of sensor, we can easily calculate the water flow. Each pulse is approximately 2.25 milliliters.

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Circuit can be summarized as :

  • Red wire of water flow sensor is connected to the 5V pin of arduino uno.
  • Black wire of water flow sensor is connected to the Gnd pin of arduino uno.
  • Yellow wire of water flow sensor is connected to the digital pin 2 of arduino uno. A pull up resistor is connected to the digital pin 2 of arduino uno.


Download arduino program from here. After completing the circuit, upload the arduino program to your arduino board. If uploading is successful, open your serial monitor. Now, blow some air through the sensor using your mouth. Pinwheel will rotate inside the sensor. Serial monitor will print the rate of flow of water (Litres / hour) through the sensor as shown in the following image.

Screenshot from 2015-05-17 23:11:07

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A deep electronic enthusiast who spent most of my time for electronic experiments. I am also interested in publishing my experiments in my blog for helping other electronics enthusiasts.