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1. A 10kO potentiometer sensor is used to measure displacement and is connected

ID: 1926072 • Letter: 1

Question

1. A 10kO potentiometer sensor is used to measure displacement and is connected to a voltage source of 5V. The full range of the displacement is 10mm. When the potentiometer is at 4mm of its maximum displacement, determine:

a. The output resistance of the potentiometer, assuming the load is infinite. (2 marks)

b. The output voltage, assuming the load is infinite. (2 marks)

c. The non-linearity error as a percentage of full output range when the load (4 marks)
resistance is 47kO.

d. The minimum value of the load resistance if the maximum non-linearity error of the potentiometer is 0.1% of full output range (load resistance RL>>Rp resistance of the potentiometer).

Explanation / Answer

a)

10k is for 10 mm

Hence for 4 mm the output resistance = 4k

b) Output Voltage = 4 X 5/ 10 = 2V

c) Load = 47k

Net resisitance = 47 X 4 /( 47 + 4 ) = 3.69k

Output voltage = 3.69 X 5 / 10 = 1.845V

Percent error = ( 2 - 1.845) / 2 = 7.75 %

d) Let the load be R

Total o/p resistance = 4R /( R + 4)

o/p voltage = 2R/ (R + 4)

2R/ (R + 4) = 1.998

R = 3996k