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Sensor Project

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Sensor Project Liquid level based on flotation and a rotary potentiometer Plan By using a rotary potentiometer connected to a cylindrical float plastic, measure the water level in a tank filling with water, as the water level moves up, the float attached to the rotary potentiometer will moves accordingly as it floats on top of the water. Find out the relationship between the volume of water and the voltage using the potentiometer as it move accordingly with the level of water. Rotary potentiometer - Movement to cause change of voltage Float arm - Connect the polystyrene to the potentiometer Circular Polystyrene - Moves as level of water goes up Measuring Cylinder - Measure the amount of water added Digital Meter - Measure the voltage across the potentiometer Clamp - Hold the potentiometer above the tank Tank - Contain water Power pack - Supply power to the potentiometer Protractor - Measure the angle of the float arm movement The Sensor Potentiometer - A variable resistor that functions as a voltage divider. Measurements to record in the experiment: Volume of Water added each time Angle of Movement of the float arm Voltage across the Potentiometer I am going to take these three measurements to investigate the relationship of the volume of water and the voltage of potentiometer when water is added to the tank. ...read more.


Average Results (+/- 0.5) Angle (Degree) (+/- 0.5) Height (CM) (+/-0.5) 2000 1.14 1.14 1.14 0 0 0 0 5 2100 1.12 1.13 1.125 0.02 0.01 0.015 1 5.5 2200 1.12 1.07 1.095 0.02 0.07 0.045 2 5.6 2300 1.12 0.95 1.035 0.02 0.09 0.055 4 5.75 2400 1.11 0.99 1.05 0.03 0.15 0.09 9 5.9 2500 1.04 0.97 1.005 0.10 0.17 0.135 13 6.2 2600 0.98 0.89 0.935 0.16 0.25 0.205 16 6.5 2700 0.94 0.81 0.875 0.2 0.33 0.265 20 6.8 2800 0.90 0.71 0.805 0.24 0.43 0.335 23 7 2900 0.91 0.69 0.800 0.23 0.45 0.34 25 7.12 3000 0.85 0.67 0.76 0.29 0.47 0.38 30 7.6 3100 0.82 0.64 0.73 0.32 0.5 0.41 32 7.8 Results The change of voltage is the voltage compared to the first voltage measured when the polystyrene was centered. Instead of using the actual voltage value, I used change in voltage because the values can be more clearly noticed when comparing to the volume of water. As the volume of water increases, the change in voltage increases. Meaning the polystyrene has driven the potentiometer to a different position every time water is added which cause the polystyrene to float higher as it stays on top of the water. ...read more.


The sensor is not very sensitive to change overall, the largest change in voltage was 0.41v and the water level was 1100ml more. The small change in voltage was cause by the length of the float arm. A longer float arm would cause greater change in voltage as it creates a bigger angle every time it moves. The moment would be bigger through a larger angle, thus create a much larger change in voltage. Calibration of the sensor is difficult as they are more than one variable from this experiment. Supposing there should only be one variable which affect how much the float arm rotates, which is the volume of water which cause the change in height of water within the tank. However the length of the arm is also a variable. A larger resistance potentiometer could be use to improve its sensitivity which would give out a larger amount of change. The sensor can be used to measure different liquid level (water , oil, etc) in different industries, when water levels drop below certain level the voltage change could trigger a device which to release more water into the tank. It could also be applied in assisting household where an alarm is set when the water level in a bath/sink has raise to a certain level as a warning. ?? ?? ?? ?? ...read more.

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