Download A) Resistance, Voltage and Current Measurement

ENT 165 INSTRUMENTATION
LABORATORY MODULE
EXPERIMENT 1
INTRODUCTION TO BASIC ELECTRICAL MEASUREMENT
ENT 165/4
INSTRUMENTATION
Semester II (2006/2007)
School of Mechatronic Engineering
Northern Malaysia University College of Engineering
LECTURER: DR. KENNETH SUNDARAJ/ MR. AZIZUL MOHAMMAD
PLV:
MR. AHMAD FIRDAUS B. AHMAD ZAIDI
TECHNICIAN: MR. MUHAMMAD FIRDAUS B. REJAB
Student’s Particular:
Name:
Matric. No:
Date:
Group:
EXPERIMENT
1
Signature:
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ENT 165 INSTRUMENTATION
INTRODUCTION TO BASIC ELECTRICAL MEASUREMENTS.
1.0 OBJECTIVE:
 The objective of this lab is to learn the operation and measurement techniques of the analog multimeter
and the oscilloscope as basic electrical instrument, and also the function generator as a signal source.
2.0 EQUIPMENT:
No
1
2
3
4
5
6
7
8
9
Item
DC power supply
Dual channel oscilloscope
Function generator
Analog Multimeter
Breadboard
Resistor 500Ω
Resistor 470kΩ
Resistor 2.2kΩ
Capacitor 1µF
Quantity
1
1
1
1
1
1
1
1
1
Remarks
R1
R2
R3
3.0 PROCEDURE:
Part 1: Measurement Using Analog Mulitmeter
3.1 Resistance Measurement
a)
Follow step-by-step procedure below to measure the value of each resistor. Record your
measurements in Table 1.
 Turn your dial to X1K Resistance Measurement Range.
 Touch your RED PROBE and BLACK PROBE together. You will see your meter needle turn
from ∞ to 0 Ω. Adjust your calibration knob until your meter needle precisely on 0Ω. (This is
the calibration procedure, needs to be repeated every time you switch dial for resistance
measurement)
 Drag your RED PROBE to the first lead of resistor and the BLACK PROBE to the second
lead. See figure 1 for details.
 Read the value of the resistor using selected range at Selector Knob.
 If you select X1K at selector knob, the value from reading scale must be multiply by 1000.
Fig. 1
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ENT 165 INSTRUMENTATION
3.2 DC Voltage Mesurement
a) Using the measured resistors in procedure 3.1, construct the following circuit on the breadboard.
(Note resistor notation value in equipment list)
b) Set the DC power supply to 5V (Vs).
Fig. 2
c) Using the analog multimeter, measure the Voltage drop on each resistor. Follow step by step
procedure below:
 Turn your dial to the suitable DC Voltage Measurement Range.
 Drag your RED PROBE to the one of resistor lead and the BLACK PROBE to the other lead.
 Read the value of the voltage using selected range at Selector Knob.
d) Record your measurement in Table 1.
3.3 DC Current Measurement
a) Using the same circuit in procedure 2 measure the current across each resistor. Follow step by step
procedure below:
 Turn your "Selector Knob" to the suitable DC Current Measurement Range.
 Brake the circuit at point where current need to be measured.
 Drag your RED PROBE to the first point and the BLACK PROBE to the second point.
 Read the value of the current using selected range at Selector Knob.
b) Record your measurement in Table 1.
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ENT 165 INSTRUMENTATION
Part 2: Measurement Using Analog Oscilloscope
3.4 Oscilloscope
Fig. 3
3.4.1 What does an oscilloscope do?
An oscilloscope is easily the most useful instrument available for testing circuits because it allows you to
see the signals at different points in the circuit. The best way of investigating an electronic system is to
monitor signals at the input and output of each system block, checking that each block is operating as
expected and is correctly linked to the next. With a little practice, you will be able to find and correct
faults quickly and accurately.
The function of an oscilloscope is extremely simple: it draws a V/t graph, a graph of voltage against time,
voltage on the vertical or Y-axis, and time on the horizontal or X-axis.
As you can see, the screen of this oscilloscope has 8 squares or divisions on the vertical axis, and 10
squares or divisions on the horizontal axis. Usually, these squares are 1 cm in each direction:
Fig. 4
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ENT 165 INSTRUMENTATION
a) Setting up your oscilloscope:
 all push button switches are in the OUT position
 all slide switches are in the UP position
 all rotating controls are CENTRED
 the central TIME/DIV and VOLTS/DIV and the HOLD OFF controls are in the calibrated, or
CAL position
b) Set both VOLTS/DIV controls to 1 V/DIV and the TIME/DIV control to 0.5 s/DIV
c) Switch ON button.
d) Push AUTO button inside. After a few moments, you should see a small bright spot, or trace,
moving fairly slowly across the screen.
e) Find the VERTICAL POSITION and HORIZONTAL POSITION so that it runs horizontally and
vertically at center of the screen.
Fig. 5
f) Now investigate the INTENSITY and FOCUS controls. Set INTENSITY and FOCUS control the
spot will be reasonably bright but not glaring, and as sharply focused as possible.
g) The TIME/DIV control determines the horizontal scale of the graph which appears on the
oscilloscope screen. Now rotate the TIME/DIV control clockwise. With the spot moving at
0.1 s/DIV, it will take 1 second to cross the screen.
h) Continue to rotate TIME/DIV clockwise. With each new setting, the spot moves faster. At around
10 ms/DIV, the spot is no longer separately visible. Instead, there is a bright line across the
screen. This happens because the screen remains bright for a short time after the spot has passed
an effect which is known as the persistence of the screen. It is useful to think of the spot as still
there, just moving too fast to be seen.
i) The VOLTS/DIV controls determine the vertical scale of the graph drawn on the oscilloscope
screen.
3.4.2 How to calibrate your oscilloscope?
a) Set your TIME/DIV at 1ms/DIV and your VOLTS/DIV on CH1 at 0.5V/DIV.
b) Select CH1 at your OUTPUT button and CAL on channel 1 at CAL position.
c) Connect BNC plug at channel1 to oscilloscope calibration output 2Vp-p / 1000 Hz like figure
below.
d) Adjust Y-POS1 and X-POS till your signal runs horizontally and vertically at center of the screen.
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ENT 165 INSTRUMENTATION
Fig. 6
3.5 Function Generator (Signal Generator)
Setting up the function generator:
a)
b)
c)
d)
e)
f)
Connect RED clip and BLACK clip to oscilloscope probe. See figure below for details.
Turn ON switch button and CAL on CAL position.
Set frequency range to appropriate range (100, 1K, 10K, 100K, 1M….)
Set frequency types (sine, square, saw tooth, triangle)
Turn AMP knob clockwise till desire Vp-p.
Turn FREQ knob (COURSE & FINE) clockwise to desire frequency till you get your frequency
display at DISPLAY PANEL.
Fig. 7
3. 6 Measuring Voltage, Frequency and Phase Difference.
a) Connect RED clip and BLACK clip to CH1 oscilloscope like figure 2.4.Set Volt/Div at 0.5 V and
Time/Div at 1ms.
b) Turn ON switch button and CAL on CAL position.
c) Set frequency range at range 1K and frequency type sine wave.
d) Turn AMP knob clockwise till you get 2 Vp-p displays at your oscilloscope
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e) Turn FREQ knob clockwise till you get your frequency display at DISPLAY PANEL 5.000 KHz.
Draw your signal in Table 2 (a).
f) Construct the following circuit. Set your Vs at 1Vp-p and 1KHz.Set your oscilloscope at DUAL
mode.
Fig. 8
g) Connect your CH1 at point A and CH2 at point B. Adjust Volt/Div and Time/Div to get the best
view of your signal display. Measure CH2 (output) signal .Draw and label both signals in Table 2
(b). Note that your CH1 at point A is your input voltage Vs.
3.7 Measuring Phase Difference:
a) Set GND for both channels. Make sure both line is horizontally at 0 positions.
 AC couple CH1 (input voltage). Adjust time/div until you get 25 small divisions per halfcycle. (Note the # divisions ,K=25 = 180˚)
 AC couple CH2 (output Voltage). Adjust CH2 Volt/Div so you get best view and suitable
reference. Count the # of small divisions between the 2 signals. This is your phase shift, P.
Calculate your phase difference Ø using formula below and draw both signals in Table 2(c) :
Ø = _P_ x 180º
K
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ENT 165 INSTRUMENTATION
Name
Matrix No
:
:
______________________________ ___
______________________________
Date: ______________
4.0 RESULT:
Table 1 (Measured results for Part 1)
Resistor Value (Ω)
Voltage Drop (Volt)
Current (A)
R1
R2
R3
Table 2 (Measured results for Part 2)
(a)
Time/Div: _________. (Sine wave)
(b)
Time/Div: _______. Volt/Div: _______.
Vout
= 1) _________ Vp-p.
2) _________ Vp
3) _________ Vrms
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ENT 165 INSTRUMENTATION
(c)
5.0 DISCUSSION
Verify your measurement results using theoretical calculation based on circuit constructed. State and
explain difference and error (if any) between your measurement and calculation. Please state also
reference (if any) to support your statement. Your discussion should also include the followings:
 Importance of equipment calibration
 Procedure of equipment
6.0 CONCLUSION
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