Wheatstone Bridge Tutorial PDF

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excellent tutorial work and questions...

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Wheatstone Bridge Tutorial The circuit below is a Wheatstone bridge:

A

R1

R2 G

R3

R4 B

1) What is meant by saying that the bridge is balanced? 2) If C= 720, R2= 320 and R3 = 360. What is R4?

3) What is an RTD?

R1

V

R2

G R4

RTD

4) If the bridge is balanced before the RTD is exposed to the temperature to be measured and R2 is adjusted by 4 ohms to rebalance the circuit. Determine the change in the RTD resistance. Note R4 is twice the value of R1.

5) a) Draw a diagram to clearly indicate how four resistance strain gauges can be mounted on the load cell body, illustrated by Figure q5a, to best indicate the applied load, F.

b) Draw a circuit diagram to indicate how to connect the strain gauges clearly identifying the position of each strain gauge and the place in the Wheatstone bridge circuit.

Figure q5a

Load Cell Body Young’s Modulus

Strain Gauges 207GPa

Poisson’s Ratio

0.3

Cross Section

6 mm x 30 mm

Gauge Factor

2.09

Nominal Resistance

120

Temperature Coefficient Maximum Current

2 x 10-6 /C 25mA

Table q5a

c) Use the data provided by Table q5a, above, to determine the maximum sensitivity of the load cell for continuous use.

d) Determine the value of a calibration resistor to simulate a load of 15 kN being applied to the load cell, with the supply voltage set to produce the maximum sensitivity....