Hi, I always get 0.04 in the serial port, and there is no change, even I block the transmit tube.

Name: Gravity: Analog Turbidity Sensor for Arduino
Brand: DFRobot
SKU: SEN0189
Price: 9.9 USD
Availability: InStock
Rating: 4.75 (4 reviews)

Please check the probe connection cable, if you plug it with a wrong side, it won't work.<img src="https://raw.githubusercontent.com/DFRobot/DFRobotMediaWikiImage/master/Image/SEN0189_Probe_Connection.jpg">

Gravity: Analog Turbidity Sensor for Arduino

Introduction

The Arduino turbidity sensor detects water quality by measuring the level of turbidity. It is able to detect suspended particles in water by measuring the light transmittance and scattering rate which changes with the amount of total suspended solids (TSS) in water. As the TTS increases, the liquid turbidity level increases. You may also check Liquid Sensor Selection Guide to get better familiar with our liquid sensor series.

This Arduino turbidity sensor has both analog and digital signal output modes. You can select the mode according to the MCU as the threshold is adjustable in digital signal mode.

Turbidity sensors can be used in the measurement of water quality in rivers and streams, wastewater and effluent measurements, sediment transport research, and laboratory measurements.

Please note that the top of probe is not waterproof!

Specification

Operating Voltage: 5V DC
Operating Current: 40mA (MAX)
Response Time: <500ms
Insulation Resistance: 100M (Min)
Output Method: Analog/Digital
Analog Output: 0-4.5V
Digital Output: High/Low-level signal (you can adjust the threshold value by adjusting the potentiometer)
Operating Temperature: 5℃~90 ℃
Storage Temperature: -10℃~90℃
Weight: 30g
Adapter Dimensions: 38mm*28mm*10mm/1.5inches *1.1inches*0.4inches