UNIVERSITI TEKNIKAL MALAYSIA MELAKA
FAKULTI KEJURUTERAAN ELEKTRONIK DAN
KEJURUTERAAN KOMPUTER
BENE 2741 / BENT 2741 / BENT 3741 / BENC 1721 / BENC 2741
LABORATORY #
LAB SESSION #
LOADING EFFECTS AND INSERTION EFFECTS
Prepared by:
Norizan Mohamad / Zahriladha Zakaria
Dept. of Ind. Electronics/ Dept. of Telecomm. Eng., FKEKK
Edited by:
Khairuddin Osman / Azdiana Md. Yusop / Adie Mohd Khafe
Dept. of Industrial Electronics
(January 2011)
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OBJECTIVES
This experiment is designed to help students to :
a) use multimeter to measure DC voltage and current of a circuit.
b) analyze and understand the error introduced during measurement.
c) explain the phenomenon of loading effects and insertion effects.
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EQUIPMENTS
1)
2)
3)
4)
5)
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Digital Multimeter (DMM)
Analog Multimeter
DC Power Supply
Resistor : 1 k, 4.7 k, 10 k, 47 k - 2 units each
100 k, 470 k - 2 units each
Project Board
PROCEDURES :
PART A: DC Voltmeter Loading Effects
1. Construct the circuit in Figure 1.
R1
A
Vin
I R2
R2
Vout
B
Figure 1
2. Set the input voltage Vin = 15 VDC. Resistors R1 = R2 = 1 k. Measure the
resistance value of R1 and R2 using DMM. Calculate and record the expected
output voltage across R2 (use the expected resistance value of R1 and R2 ).
3. Using analog multimeter, measure and record the output voltage across R2.
4. Using digital multimeter, measure and record the output voltage across R2.
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5. Repeat steps 2 to 4 by replacing R1 and R2 to 4.7 k, 10 k, 47 k, 100 k
and 470 k resistors.
6. Write down your measurement in steps 2 to 5 in a table.
7. For each measurement and expected values in step 6, calculate the
percentage error of DC voltmeter for both analog and digital multimeter.
8. Draw a line graph of percentage error vs. resistors R2 for both analog and
digital voltmeter. Compare the graphs. Explain the variations of loading error
on your graphs.
PART B: DC Ammeter Insertion Effects
1. Use the resistors and circuit in Part A.
2. Set the input voltage Vin = 15 VDC. Resistors R1 = R2 = 1 k. Measure the
resistance value of R1 and R2 using DMM. You can also use the measured
value in Part A. Calculate and record the expected current flow through R2
(use the expected resistance value of R1 and R2 ).
3. Using analog multimeter, measure and record the current flow through R2.
4. Repeat steps 2 & 3 by replacing R1 and R2 to 4.7 k, 10 k, 47 k, and
100 k resistors.
5. Write down your measurement in steps 2 to 4 in a table.
6. For each measurement and expected current values in step 5, calculate the
percentage of DC Ammeter insertion error.
7. Draw a line graph of percentage insertion error vs. total resistance R1 + R2.
Discuss any variations of insertion error from your graph.
Note: make conclusion on your observations and findings for the measurement error
due to loading and insertion effects in Part A and Part B. Give your opinions on how
to reduce the errors.
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