Universiti Malaysia Perlis
DKT 111/3 – ELECTRIC CIRCUITS PRINCIPLES
LAB ASSIGNMENT 1
PART A :INTRODUCTION TO LABORATORY EQUIPMENT (MULTIMETER)
PART B : COMPONENT CODING AND RESISTOR MEASUREMENT
Pn. Nazatul Syima Bt. Saad
Pusat Pengajian Kejuruteraan Komputer Dan Perhubungan
DKT111/4 ELECTRIC CIRCUIT PRINCIPLE
LABORATORY MODULE
Universiti Malaysia Perlis
LAB ASSIGMENT 1 (PART A)
INTRODUCTION TO LABORATORY EQUIPMENT (MULTIMETER)
OBJECTIVE
1. To familiarize students in using multimeter to measure resistance, voltage and current as
a basic tool in measurement.
2. To make students understand how to do real connections or wiring in the laboratory
based on the given schematic diagram using breadboard to easily connect components
together to build circuits.
INTRODUCTION
BREADBOARD
When building a "permanent circuit" the components can be "grown" together (as in an
integrated circuit), soldered together (as on a printed circuit board), or held together by
screws and clamps (as in house wiring). In lab, we want something that is easy to assemble
and easy to change. We also want something that can be used with the same components
that "real" circuits use. Most of these components have pieces of wire or metal tabs sticking
out of them to form their terminals.
A breadboard is used to make up temporary circuits for testing or to try out an idea. No
soldering is required so it is easy to change connections and replace components. Parts will
not be damaged so they will be available to re-use afterwards.
Figure 1.3: Front look of a typical small breadboard used in the laboratory
The breadboard has many strips of metal (usually copper) which run underneath the board.
Figure 1.4: The metal strips layout
When wiring, it is important to keep your work neat! This will save time in debugging when
your circuit doesn’t work. Here are some tips: Keep your wires short, do not loop wires over
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the chip, use the bus lines for Ground or a DC supply voltage (e.g. VCC) and sometimes to
get cleaner signals, short the metal base of the breadboard to the circuit’s ground.
MULTIMETER
Multimeter is a basic tool in electric and electronic fields. It is a multipurpose device to
measure voltage, current and resistance. Basically there are two types of multimeter used
either in the education or industrial field based on the electronic circuits inside them: analog
and digital meters. The analog meter, broadly known as VOM (volt-ohm-miliammeters) uses
a mechanical moving pointer which indicates the measured quantity on a calibrated scale. It
requires the user a little practice to interpret the location of the pointer. The digital meter
broadly known as DMM (digital multimeter) used number or numerical display to represent
the measured quantity. It has high degree of accuracy and can eliminate usual reading
errors compared to the analog meters. Students should be adept at using both meters
throughout their studies.
Resistance Measurement: For VOM always reset the zero-adjust whenever you change
scales. In addition always choose the range setting that will give the best reading of the
pointer location. As an example, to measure a 500-Ω resistance, choose function switch
resistance with a range setting of X 1k. Finally do not forget to multiply the reading by the
proper multiplication factor. If you are not sure about the value always starts with the highest
range and going downwards until appropriate scale is chosen. For DMM remember that any
scale marked “kΩ” will be reading in kilo-ohms and any with “MΩ”scale in mega-ohms and
so on. There is no zero-adjust on a DMM meter but make sure that the resistance reads
zero when shunting both leads. Polarity does not concern in resistance measurement. Either
lead of the meter can be placed on either terminal end of the component, it will be the same.
Voltage Measurement: When measuring voltage levels, make sure the meter is connected
in parallel with the element whose voltage is to be measured. Polarity is important because
the reading will indicate up-scale or positive reading for correct connection and down-scale
or negative reading if reverse connection of the meter test leads to the resistor’s terminals.
Therefore a voltmeter is not only excellent for measuring voltage but also for polarity
determination. Choose the correct function switch for example DCV to measure dc voltage
and turn to the range switch that has slightly bigger value than the voltage to be measured.
Current Measurement: When measuring current levels, make a series connection between
the meter and the component whose current is to be measured. In other words, disconnect
the particular branch and insert the ammeter. The ammeter also has polarity marking to
indicate the manner they should be hooked-up in the circuit to obtain an up-scale or positive
measurement. For analog meter pay attention that reversing the polarity of the meter may
cause damage to the pointer. Again always start with higher range going downwards to
avoid damaging the instrument.
The connection of the multimeter to measure different electrical quantities is shown in both
schematic diagram and real wiring illustration in the laboratory in Figure 1.5.
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R
Vs
V /Ω
A
Figure 1.5(a): Schematic diagram
Multimeter as Ohm Meter
Experiment 1
Connect the meter's test probes across the resistor as such, and note its indication on the
resistance scale:
Figure 1.6 – Measuring resistors
If the needle points very close to zero, you need to select a lower resistance range on the
meter, just as you needed to select an appropriate voltage range when reading the voltage
of a battery.
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Experiment 2
Figure 1.7 - Measuring breadboard’s continuity.
Use your meter to determine continuity between the holes on a breadboard as in Figure 6.
(Use small gauge solid wire to insert into the holes of the breadboard), redraw the board with
line showing its connectivity.
Experiment 3
Figure 1.8 – Measuring circuit resistance
For the circuit below ( figure 7) , measure the voltage between point ab, when
a) R1 = 1 kΩ, R2 = 2.2 kΩ and R3 = 4.7kΩ.
b) R1 = 200 kΩ and R2 = R3 =10 kΩ.
Multimeter as Volt Meter
Voltmeter is an electrical instrument which is use to measure potential difference between
two points. Potential difference or voltage between points are measure in volts, V. Bigger
voltage value indicates current from higher potential terminal has more energy and are
readily to move to lower potential terminal. Voltage is a vector quantity and always measure
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between two points. Point voltage refers the voltage of that single point to a common point
(electrical ground). Voltmeter has very high internal resistance, and is connected in parallel
across components.
Figure1.9 – Voltmeter
connection in parallel
Reading the Voltage Scale
Figure 2.0 – Analog Multimeter’s Screen
The actual reading of a voltmeter is made up of the combination of selector’s voltage range
and meter reading (needle position). Three different scales are available (10, 50 and 250) on
an analog voltmeter.
Measured voltage = voltage range x corresponding meter reading (needle)
Example
The measurement shown in Figure 3 may be:
1) Range selection = 10
Measured voltage = 4.4 V
2) Range selection = 1000
Measured voltage = 440 V
3) Range selection = 0.1
Measured voltage = 0.44 V
4) Range selection = 50
Measured voltage = 22 V
5) Range selection = 250
Measured voltage = 110 V
6) Range selection = 2.5
Measured voltage = 1.1 V
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Experiment 1
Figure 2.1 – Series LED circuit
On your breadboard, construct the circuit as shown in Figure 5. Connect battery terminal to
DC power supply and sweep the supply voltage from 0.0 V to 40.0 V. Measure the voltages
across R1(1 kΩ), D1, D2 and D3 for all supply voltage and calculate the point voltages as
shown in Table 1.
No
1
2
3
4
5
6
7
Supply
Voltage (V)
8.0
10.0
12.0
14.0
16.0
18.0
20.0
VR1
VD1
VD2
VD3
VA
VB
VC
Table 1 – Voltage measurement
Multimeter as Ammeter
The actual reading of an ammeter is made up of the combination of selector’s
current range and meter reading (needle position). The Ampere scale uses the
similar scale of the voltmeter
Measurement
1. Point selector to highest current range.
2. Touch the probe leads across measurement points (red terminal to current
entry point).
3. If the reading is too small, disconnect probe and adjust range until readable
value is obtained.
Caution
1. Never connect Ammeter in parallel.
2. Always disconnect probe when adjusting the range selector.
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VD
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Experiment 1
Referring to figure 1.8 measuring the current cross each resistor with Voltage supply 3V.
Resistor
R1
R2
R3
Current
~ ooooo End ooooo~
APPENDIX A: SANWA ANALOG METER
Figure A1: Names of components
a) Precaution for safety measurement
i.
To ensure that the meter is used safely, follow all safety and operation
instructions.
ii.
Never use meter on the electric circuit that exceed 3kVA.
iii.
Never apply an input signals exceeding the maximum rating input value.
iv.
Pay special attention when measuring the voltage of AC30Vrms or DC60V or
more to avoid injury.
v.
Always keep your fingers behinds the finger guards on the probe when making
measurements.
vi.
Before starting the measurement, make sure that the function or range properly
set in accordance with he measurement.
vii.
Be sure to disconnect the the test pins from the circuit when changing the
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DKT111/4 ELECTRIC CIRCUIT PRINCIPLE
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function or range.
viii.
For details, please refer instruction manual.
b) Preparation for Measurement
i.
Adjustment of meter zero position
ii.
Turn the zero position adjuster so that the pointer may align right to the zero position.
Range selection: Select a range proper for the item to be measured. Set the range
selector knob accordingly.
c) Measuring DCV
i.
ii.
iii.
Set the range selector knob to an appropriate DCV range.
Apply the black test pin to the minus potential of measured circuit and the
test pin to the plus potential as in Figure A2.
Read the move of the pointer by V and A scale.
red
Figure A2
d) Measuring DCV (NULL)
i.
ii.
iii.
iv.
Set the range selector knob to an appropriate range.
Turn the adjuster so that the pointer may align exactly to 0 by DCV scale.
Apply the black test pin to the negative potential side of the circuit and the red
test pin to the positive potential side as in Figure A3.
Read the move of the pointer by DCV scale.
Figure A3
e) Measuring ACV
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i.
ii.
iii.
Turn the range selector knob to an appropriate ACV range.
Apply the test leads to measured circuit as in Figure A4.
Read the move of the pointer by V and A scale. (Use AC 10V scale for 10V range
only)
Note: Since this instrument employs the mean value system for its AC voltage
measurement circuit, AC waveform other than sine wave may cause error.
Figure A4
f) Measuring DCA
i.
ii.
iii.
iv.
Connect the meter in series with the load.
Turn the range selector knob to an appropriate DCA range.
Take out measured circuit and apply the black test pin to the minus potential of
measured circuit and the red test pin to the plus potential as in Figure A5.
Read the move of the pointer by V and A scale.
Figure A5
g) Measuring Resistance (Ω)
Precaution: Do not measure a resistance in a circuit where a voltage is present.
i.
ii.
iii.
iv.
v.
Turn the range selector knob to an appropriate Ω range.
Short the red and black test pins and turn the 0Ω adjuster so that the pointer may
align exactly to 0Ω. (If the pointer fails to swing up to 0Ω even when the 0Ω
adjuster is turned clockwise fully, replace the internal battery with a fresh one.)
Apply the test pin to measured resistance as in Figure A6.
Read the move of the pointer by Ω scale.
Note: The polarity of (+) and (-) turns reverse to that of the test leads when
measurement is done in Ω range.
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Figure A6
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LAB ASSIGMENT 1 (PART B)
COMPONENT CODING AND RESISTOR MEASUREMENT
OBJECTIVE
1. To acquaint students with the skill to read resistor and capacitor values based on color
code and digital/alphabet code.
2. To make students understand how to do real connections or wiring in the laboratory
based on the given schematic diagram using breadboard to easily connect components
together to build circuits.
INTRODUCTION
RESISTOR CODING
The color code technique is used to show resistance values of carbon resistors without
having to measure it. In this technique color bands are printed on the resistor. The
procedure for determining the resistance of a color-coded resistance is described in Table 1.
The first two bands determine the first two digits of the resistor value, while the third band
determines the power of 10-multiplier. For the resistor with value less than 10 Ω the third
band is either silver or gold. The forth band is the percent tolerance for the chosen resistor. If
resistors have only three bands, it means the forth band has no color. Sometimes a fifth
band is employed for some high precision resistor where the first three bands represent the
significant digit. The forth band is the multiplier while the fifth band is the tolerance. In the
other case, for some standard 4-band code, a fifth band may indicate the manufacturer’s
special code for some physical characteristic or failure rate of the component.
For increasing wattage, the size of resistor will increase accordingly. The larger sized
resistors from about 5 W and up or wire winding resistors are not color-coded but are using
digital and alphabet code printed on its body. In writing the value of resistors: k stands for
multiplier “kilo” and M for multiplier “mega”. The alphabet written after the resistor value
shows the tolerance: F = 1%, G = 2%, J = 5%, K= 10% and M = 20%.
Resistance should never be measured in a live network due to the possibility of damaging
the meter with excessively high currents and obtaining readings that have no meaning. In a
constructed circuit, to measure a single resistance value, just take off one end of its terminal
to avoid the effect of other resistances in the circuit. This applies in the same manner to the
other components such as capacitor and inductor.
The standard code is adopted by manufacturer through their trade association, the
Electronic Industries Association (EIA).
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DKT111/4 ELECTRIC CIRCUIT PRINCIPLE
Color
LABORATORY MODULE
4th Band
(Tolerance)
1st Band
st
(1 Significant Digit)
2nd Band
nd
(2 Significant Digit)
3rd Band
(Multiplier)
0
1
2
3
4
5
6
7
8
9
-
0
1
2
3
4
5
6
7
8
9
-
1
101
102
1 03
104
105
106
107
108
109
0.1
0.01
5%
10%
-
-
-
20%
Black
Brown
Red
Orange
Yellow
Green
Blue
Violet
Grey
White
Gold
Silver
No
Color
1%
2%
3%
4%
Table 1.1: Resistor color coding
Figure 1.1: Reading resistor color coding
Example 1:
1
The value of this resistor is 25 x 10 ±
10% = 250± 10% ohms
Example 2:
R33F = 0.33 ±1% Ω
4k7 = 4.7 x 103 Ω
10R0 = 10 Ω
200R = 200 Ω
6k8J = 6.8 x 103 Ω ±5%
R39 = 0.39 Ω
2k2M = 2.2 x 103 ±20%
1R0 = 1 Ω
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CAPACITOR CODING
Same as resistors, most of the capacitors have their nominal value printed directly on them
using digital/alphabet code according to the EIA coding system. This code is generally given
in picofarads (pF), which means that we need to manipulate the value if we want the value in
microfarads (µF) or nanofarads (nF). Some capacitors have polarity (positive and negative)
which must be connected according to their polarity in order for the capacitor to operate
such as the electrolytics capacitors. Normally the negative leg of electrolytics capacitor could
be recognized by the white stripes at the body and/or the negative leg is shorter then the
positive leg.
Some types of capacitors are shown in Figure 1.2 below.
Figure 1.2: Different types of capacitors construction
Example 3:
Capacitor marked 104 has value of 10 with 4 zeroes after it, or 100,000pF (equivalent to 100
nF or 0.1 µF)
Capacitor marked 681 = 68 with single zero or 680 pF
Capacitor marked 472 = 47 with 2 zeroes or 4700 pF (equivalent to 4.7nF)
Alternatively, the value may be given directly in nanofarads with three significants digits but
the thirds generally ‘0’. In this case there is generally also a small ‘n’ which can be used in
place of decimal points.
Example 4:
Capacitor marked 220n has 220nF capacitances (equivalent to 0.22F)
Capacitor marked 3n3 has 3.3nF capacitances (equivalent to 3300pF)
Some of the capacitors have a capital letter to indicate their tolerance rating. Below is
capacitor tolerance marking codes:
F
± 1%
G
± 2%
J
± 5%
K
± 10%
Example 5:
104K = 0.1µF ± 10%,
4n7J = 4.7nF ± 5%
14
M
± 20%
Z
-20%, +80%
DKT111/4 ELECTRIC CIRCUIT PRINCIPLE
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Figure 1.5(b): Real wiring diagram for illustration
EQUIPMENT/COMPONENT
Multimeter (1)
Adjustable DC power supply (1)
Resistor (1/4 W) – 1 kΩ , 2.2 kΩ, 4.7 kΩ, 15 kΩ,
680 Ω, 27 kΩ, 3.9 kΩ
Breadboard (1)
**For non-measured resistor and capacitance values students are strictly required to
complete the answers before the lab session. Otherwise they will be forbidden from
participating the session.
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PROCEDURE
PART A: READING RESISTOR BY COLOR CODING
Determine the nominal value or color bands of a particular resistor based on color coding
technique for each case given in Table 1.2 below. Check your answers with the measured
values in the laboratory.
COLOR BAND
No.
Band 1
Band 2
Band 3
Band 4
Nominal
Value
Measured
Value (Ω)
Within
Tolerance?
YES/NO
1.
brown
black
red
gold
2.
blue
grey
brown
gold
3.
yellow
violet
orange
gold
4.
red
red
orange
gold
5.
3.9kΩ ± 5%
6.
15kΩ ± 5%
7.
27kΩ ± 5%
Table 1.2: Exercise for determining resistor values by color coding and measurement
PART B: READING RESISTOR AND CAPACITOR BY DIGITAL/ALPHABET CODING
Determine the nominal value of a particular resistor based on digital/alphabet coding
technique for each case given in Table 1.3 below.
DIGITAL/ALPHABET CODE
3k9
1R0
8M5
R56
NOMINAL VALUE (in ohm)
Table 1.3(a): Exercise for determining resistor values by digital/alphabet coding
DIGITAL/ALPHABET CODE
33J
104
3n3J
103Z
NOMINAL VALUE( in nanofarad)
Table 1.3(b): Exercise for determining capacitor values by digital/alphabet coding
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PART C: USING MULTIMETER TO MEASURE RESISTANCE, VOLTAGE AND CURRENT
EXERCISE 1:
Using the supplied equipments/components in the laboratory, hook-up the series resistive
circuit as in Figure 1.6. As a common practice, always measure the actual value of the
resistors used in the circuit and set the source value using multimeter to reduce errors from
the expected results. Perform the following instructions.
Measured values:
R1 = ________ Ω
R2 = ________ Ω
R3 = ________ Ω
Figure 1.6: Simple series resistive circuit
1. Measure currents I1 and IT. Should they be the same? Give your reason.
Answer:
I1 = ________ mA
IT = ________ mA
Comment:
_________________________________________________________________________
_______________________________________________________________________
2. Measure voltage drop across resistor R1.
Answer:
VR1 = ________ V
3. Measure voltage drop across the combination resistors R2 and R3.
Answer:
VR2R3 = ________ V
4. Disconnect the power supply and measure the total resistance in the circuit, Req.
Answer:
Req = ________ Ω
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EXERCISE 2:
Modify the previous series circuit connection to reconstruct a parallel resistive connection as
in Figure 1.7. Perform the following instructions;
Figure 1.7: Simple parallel resistive circuit
1. Measure currents I1, I2, I3 and IT as indicated in the above diagram using miliammeter.
Answer:
I1 = ________ mA
I2 = ________ mA
I3 = ________ mA
IT = ________ mA
Comment:
_________________________________________________________________________
_______________________________________________________________________
2. Use the ohmmeter to measure the equivalent resistance Req of this circuit. Does the
result equal to the one measured in Exercise 1?
Answer:
Req = ________ Ω
Comment:
_________________________________________________________________________
_______________________________________________________________________
3. Measure voltage drop across R1, R2 and R3. What can you conclude from these results?
Answer:
VR1 = ________ V
VR2 = ________ V
VR3 = ________ V
Comment:
_________________________________________________________________________
_________________________________________________________________________
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Discussion:
Conclusion:
~oooo000oooo~
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