Fascinating project. Can you give us some more detail about your experimental set-up? (eg a diagram or sketch?)
and also on the characteristics of the liquid you are using, as if its homogeneous this may not work?
I dont have a sketch of the actual prototype but I have of the old one with and LED and a LDR and the idea is the the same.
The only difference is that the actual has a infrared LED and a fototransistor.
OBS: I dont know how to attach an Image here so I atacched it at the end.
So the main objective is to measure if the water that Im receiving at home is always clear, for now I dont want to measure the turbidity in any scale (NTU, FTU, ...).
Im trying to make three equal sensors, so now I am analyzing their behavior with the same liquid and observating if they suffer the same variation from one sample to another. To make some tests with the sensor I am soiling (I dont know if it the correct word I used google translator for this one) the water with some dirt, coffee, milk.
So you should not expect a smooth signal. Perhaps you could do a statistical analysis of the variations you are seeing; in any case, the fact you ARE seeing variation is a good sign your messurement system is working.
In the future I will try to make some statics analizing.
Are you measuring transmitted or 90 degree scattered light? or both? and how are you collimating the light from the LED?
Currently I am using a 180º sensor but i think that i will make another prototype with the 90º and compare them.
I am not collimating the light, i didnt even think about it. I will make some research about it