German University in Cairo

Sensor Technology (ELCT903)

Assignment (2)

Due Date: 16/10/2011

- Please hand in your assignment to your TA during the tutorial - Please print and solve in this form, other prints will not be

accepted. Name: ………………………………………… Group: .……… Application #:………..

Question 1

A bourdon tube pressure gauge requires 10 bar to produce 3 vernier division changes in the scale. Determine its static sensitivity.

Solution

Question 2

The amplifier system of a Cathode-ray oscilloscope (CRO) is stated to have sensitivity of 2.2cm/V. what would be the deflection on the screen for an input of 0.38V?

Solution

Question 3

A potentiometer resistance transducer has a total winding resistance of 8k and a maximum displacement range of 5 cm. The power dissipation at maximum displacement is not to exceed 50 mW.

Determine the output voltage of the transducer when the input displacement is 2cm.

Solution

Question 4

Consider the RTD type temperature sensor is used to measure the temperature of a location. The two terminals of the sensor are connected to the R1 position of the Wheatstone bridge circuit.

The sensor temperature resistance relationship is as follows:-

From the sensor calibration data it is known that

Reference temperature

At temperature To

Assume that Vi = 10 VDC and R2 = R3 = R4 = 200

What is the temperature when the Vo = 0.5 VDC? In condition that

- input resistance of the voltage measurement device is assumed to be infinity - input resistance of the voltage measurement device is assumed to be about 1M -

Solution

1004.0 −= Coα

CT oo 0=

Ω= 200oR

( )[ ]00 1 TTRRt −+= α

Question 5

A compressive force is applied to a structure the strain = 5 microstrain.

Two separate strain gauges are attached to the structure.

One is a nickel wire strain gauge of gauge factor = - 12.1 and the other is nicrome wire strain gauge of gauge factor = 2

Calculate the value of resistance of the gauges after they are strained. The resistance of the strain gauge =120

Solution

Question 6

For El-Salam cable stayed bridge crossing over the Suez Canal, it is required to measure the amount of bending in the metal bar.

• Suggest and explain for a sensor that can do the job. • Explain the theory of operation and the equations that correlate this operation. • Derive an expression for the output voltage in terms of the selected sensor and signal

conditioning circuit parameters. Show your design such that the final output should be an electrical measureable signal.

• Draw a block diagram for the data acquisition system.

Solution