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?
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.
Are you measuring transmitted or 90 degree scattered light? or both? and how are you collimating the light from the LED?
If you know about any more projects like this one, please send it to meThanks for your attention
Im using a 10k ohm pull up resistor what would happen with the reading if I reduce or increase it?
I think I answered this before. Increasing it will make it more sensitive. As a transistor is a current operated device the voltage changes more across a higher value resistor than a lower one for any given current through it. Its called ohms law.
You should aim to get the un - illuminated photo transistor to give very roughly a reading of 512, you can change this by altering the 10K value.
Potential dividers work best when the two legs are about the same because any change in the sensor's value.
So i tried many resistors to reach readings near 512 while the sensor is un-ilumininated but i think something is weird. I tried a wide range of resistor but still the reading are high.1k -> Un-iluminated Sensor = 9952.2k -> Un-iluminated Sensor = 994/9953.3k -> Un-iluminated Sensor = 994/99510k -> Un-iluminated Sensor = 992/99322k -> Un-iluminated Sensor = 990100k -> Un-iluminated Sensor = 9831M -> Un-iluminated Sensor = 824My schematic:
the actual has a infrared LED and a fototransistor.
So i tried many resistors to reach readings near 512 while the sensor is un-ilumininated