Converting Voltage to Turbidity

userHead Account cancelled 2018-08-15 11:49:35 2180 Views1 Replies
I am getting a value of 5 for voltage when the sensor is placed in clear water. If I use the equation: y=-1120.4x^2+5742.3x-4352.9 to calculate the corresponding Turbidity, i get a negative value (-3651.4) whereas it should be 0. Any suggestions to resolve this please ?
2018-08-15 16:06:58 this is perfectly normal, as according the diagram where you got that formula from, you shouldn't get any value over ~4.2V (nor under ~2.5V) :

are you sure the onboard switch is on the analog position ? I feel like you might be reading the "digital" (binary) output.
I missed it first on wiki but it's clear once you have a look at the schematics.
wiki wrote: Interface Description:
  1. "D/A" Output Signal Switch
    1. "A": Analog Signal Output, the output value will decrease when in liquids with a high turbidity
    2. "D": Digital Signal Output, high and low levels, which can be adjusted by the threshold potentiometer
  2. Threshold Potentiometer: you can change the trigger condition by adjusting the threshold potentiometer in digital signal mode. ... ematic.pdf
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