How to Make: Water Turbidity Sensor




In this tutorial, we will explain how to make a water turbidity sensor that can measure three different levels of turbidity.

This is our final product in action!

Step 1: What Do You Need?

- Particle Photon + breadboard

- Laser


- On/off button

- Small resistor (220 Ohm)

- Electrical wires (different sizes)

- PVC tube

- Smaller see through tube

- 4 plastic cards (cut in circles with diameter that of the PVC tube)

- Solder tin

- Glue

- Sealant

Step 2: Connecting Your Particle Photon

For more details on how to connect to your Photon, see this link:

Step 3: Connecting All the Components

Connect all the components you have according to the pictures! Make sure every pin is tightly connected. For the LDR and laser to fit in the tube, it is advised to connect and solder them to longer wires (2nd picture). Lead all the wires through a plastic card (cut in circle) because this is going to cover up the tube.

Step 4: Write Program

This is the program we initiall used while developing our sensor. It has not been calibrated yet. It is advised to run this program on your Photon to see if it works.

Step 5: Installing in the Tube

Make a hole in the tube, the exact location does not really matter. As long as the LDR and laser still fit without hindering the hole.

Place the LDR and the laser in a plastic circle as seen on the picture.

Put the LDR and the laser in the tube.

The LDR should be on the opposite side from the hole compared to the laser.

Glue both plastic circles (with the LDR and laser) To the side of the tube just next to the hole.

Place the plastic invisible tube through the hole and cut it so it looks nice to you.

Finally glue the other 2 plastic cards to the top and bottom of the tube to close it off.

TIP: Colour code all the wires so that you still know which wire belongs where once you closed the tube.

Step 6: Sealing the Tube

Seal all the connections and open edges with sealant to prevent water from reaching the inside of the tube.

Step 7: Calibration

Our sensor is made to measure 3 types of turbidity levels. To calibrate your sensor, take some fresh water and something to make the turbidity higher (we used coffee with creamer).

Start by measuring the clear water. Write down this value.

Then add some of the coffee until the measured value is well above the clear water value. (we had a difference of 300). Measure and write down the value.

The add the rest and measure again. Write down the value.

The more often you do this the more accurate you can calibrate your sensor.

Now in your program adjust the limits to match your measured values! In the picture you can see what our values are after calibration.



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    8 Discussions


    1 year ago

    What kind of laser did you use? If possible, could you send the link to the product? We need to make this for a tech project


    1 year ago

    How high of a measurement can you get ? ie what's the max PPM your unit will read ?

    3 replies

    Reply 1 year ago

    The Particle Photon delivers values on a scale of 0 to 4096. The LDR measures the light. Completely dark will give a value of 4096 and completely light will give 0. Because of inaccuracies our clear water value is already around 2700. Is this what you asked for?


    Reply 1 year ago

    Yes - sort of. We're looking for a turbidity meter to measure values up t0 250g/L (250,000ppm). They're not readily available to purchase which is why I was interested in your set up. I'm guessing it can be calibrated to whatever known values you provide as calibrated baselines. Thank you


    Reply 1 year ago

    Yes for this you need to calibrate with samples of which you do know the ppm!


    1 year ago

    Why not actually calibrate the sensor. Use a lab standar and know what you have.