Turbidity is to measure the particulate matter in the water. It needs to be read by the analog port of the single-chip microcomputer for calculation. It needs a turbidity calibration fluid to calibrate. It does not directly measure the voltage with a multimeter. The output voltage of each module is different. The module should be used in dark and light temperature. Voltage will make the output voltage of the module different, 0-4.5 is just the reference voltage.

parameter

Voltage: 3.3-5V (with anti-reverse circuit)
Output: default analog (high and low level output can be set)
Measuring range: 0-1000NTU