Turbidity sensor calibration and NTU
Anand.Jhaveri 2024-02-20 04:30:34 1190 Views3 Replies I have recently bought the Gravity: Analog Turbidity Sensor.
I am now trying to convert the voltage from the sensor into an NTU reading.
I saw the equation in your documentation to go from volt to NTU. However, the clear water reading is expected to be 4.2volts, whereas I am getting 3.8volts. Turning the potentiometer on the board has no impact at all on the voltage. The 3.8 volt reading continues, regardless of the potentiometer position.
So, not sure exactly how to proceed.
Please could you guide me on how to resolve this and calculate the correct NTU's?
Regards,
Anand.
There is also a tiny potentiometer under the white cap, approx. 3mm large, it looks like a screw. This was the only way I found to increase the voltage when there is nothing between the light source and the probe. According to the quadratic equation on the wiki, you reach 0 NTU with 4.2V. Since I could not tune the voltage that precisely, I used the code to create an offset through calibration.
Xtoph Test the sensor with solutions of known turbidity to verify its accuracy. This can help determine if the sensor is functioning correctly or if there is an issue with its calibration.You can merge turbidity, TDS, and pH sensors into a single PCB via KiCad for compactness and efficiency gains in size and assembly.
https://www.pcbway.com/project/shareproject/PCB_DESIGN_AND_DEVELOPMENT_FOR_PH_TURBIDITY_AND_TDS_MODULES_5a8d79e8.html
lia.ifat hi Anand.
the reading have a +/-0.3v error. (in the pure water, that is NTU < 0.5, it should output “4.1±0.3V”) 3.8 ≤ yourRead ≤ 4.4
i think, that 3.8 is ok..
now. how you get the 3.8v?? i can't do. All my test are up 5.5 =(
henryk 
