The turbidity sensor can measure the turbidity of the water (the number of suspended particles).

The optical sensor of this module can measure the density of turbid water and the concentration of extraneous matter using the refraction of wavelength between photo transistor and diode. By using an optical transistor and optical diodes, an optical sensor measures the amount of light coming from the source of the light to the light receiver, in order to calculate turbidity of water.

The output mode can be selected by adjusting the switch on the board. Supports analog and digital output. The sensitivity can be adjusted by the on-board knob.

Features:

Low power consumption
Small size: 2.0cm x 4.0cm Module
Only 3 pins needed, save I/O resources
Easy to use:plug and play
Output mode optional, support analog output and digital output

Specification:

Operating Voltage: 3.3V/5V DC
Output Interface: Analog, Digital
Size 20*40mm

Typical applications:

Measure the water pollution degree of washing machines such as dishwashers to determine the optimal washing time and rinsing times. 
Industrial site control.
Environmental wastewater treatment.