UNIVERSITI MALAYSIA PERLIS
COURSE NAME
BASIC ENGINEERING SKILLS
COURSE CODE
DCT 100/ 3
LAB NO.
2
LAB MODULE
ELECTRONIC CIRCUIT
LEVEL OF COMPLEXITY
1
2
3
4
5
6
KNOWLEDGE
COMPREHENSION
APPLICATION
ANALYSIS
EVALUATION
SYNTHESIS
√
√
√
ENGINEERING CENTRE
DCT100: Basic Engineering Skills
Electronic Circuit Lab Module
Contents
Objectives …………………………………………………………………………………. 1
Introduction………………………………………………………………………………. 1
Lab Instruments .………………………………………………………………………..5
Introduction to Soldering Process ……………………………………………. 13
Soldering Techniques ………………………………………………………………. 14
Lab Activities ……………………………..……………………………………………. 21
This module is available for students in UniMAP Portal.
portal.unimap.edu.my
Engineering and Innovation Centre
University Malaysia Perlis
Kampus Pauh Putra
02600 Arau
Perlis
DCT100: Basic Engineering Skills
LAB 2 :
Electronic Circuit Lab Module
PROTOTYPING TECHNIQUE, TEST &
MEASUREMENT OF ELECTRONIC CIRCUIT
OBJECTIVES:
At the end of this lab session you should be able to
i.
identify basic electronic components and its properties.
ii.
know basic prototyping technique by using Vero board.
iii.
perform soldering skills with good results.
iv.
use basic lab instruments; power supply unit, oscilloscope, and function
generator
INTRODUCTION
In this section, a simple introductory to a few electronic components will be
carried out based on one timer circuit. A brief explanatory about lab instruments
will be discussed then.
Figure 1: Timer Circuit
Component Listing
Resistor – 10kΩ, 47kΩ and 470Ω
Capacitor - 100µF and 0.01µF
555 Timer
LED
Switch
1 | 2014 Universiti Malaysia Perlis
DCT100: Basic Engineering Skills
Electronic Circuit Lab Module
RESISTOR
Black Brown Red Orange Yellow Green Blue Violet Gray White
0
1
2
3
4
5
6
7
8
9
Table 1: Resistor’s Colour Codes
Figure 2: Resistor and its symbol
How to read the code ?
a) First find the tolerance band, it will typically be gold ( 5%) and
sometimes silver (10%).
b) Starting from the other end, identify the first band - write down the
number associated with that color; in this case Blue is 6.
c) Now 'read' the next color, here it is red so write down a '2' next to the
six. (you should have '62' so far).
d) Now read the third or 'multiplier' band and write down that
number of zeros. In this example it is two so we get '6200' or '6,200'.
If the 'multiplier' band is Black (for zero) don't write any zeros down.
If the 'multiplier' band is Gold move the decimal point one to the left.
If the 'multiplier' band is Silver move the decimal point two places to
the left. If the resistor has one more band past the tolerance band it is a
quality band.
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DCT100: Basic Engineering Skills
Electronic Circuit Lab Module
CAPACITOR
(a) Polarized
(b) Non-polarized
Figure 3: Capacitor and its symbols
1. Large capacitor have the value printed plainly on them, such as 10.µF (Ten
Micro Farads) but smaller disk types along with plastic film types often
have just 2 or 3 numbers on them.
2. First, most will have three numbers, but sometimes there are just two
numbers. These are read as Pico-Farads. An example: 47 printed on a
small disk can be assumed to be 47 Pico-Farads.
3. For the 3 numbers, it is somewhat similar to the resistor code. The first two are
the 1st and 2nd significant digits and the third is a multiplier code. In the table
below show the value of the third significant digit. The result from the
multiplication is in Pico-Farad.
Third digit
0
1
2
3
4
5
6
7
8
9
Multiplier (the first two digits gives you the
value in Pico- Farads)
1
10
100
1,000
10,000
100,000
not used
not used
.01
.1
Table 2: Multiplier Table for Capacitor
Example: A capacitor marked 104 is 10 with 4 more zeros or 100,000 pF
which is otherwise referred to as a .1 µF capacitor.
3 | 2014 Universiti Malaysia Perlis
DCT100: Basic Engineering Skills
Electronic Circuit Lab Module
TIMER (555)
Figure 4: Timer IC
1. The 555 is a highly stable device for generating accurate time delays or
oscillation.
2. The pin description of this IC is given in figure 5 below.
Figure 5: 555 Timer Pin Descriptions
3. The basic operation for 555 timer is as shown in figure 1, where the
parameter C1 and R1 determine the time period for output pin (6) to
become ‘hi’ where the LED will be on for 5 seconds with 100 µF for C1
and 47 kΩ for R1.
4. User may try to change the value for C1 and R1 where R1 should be in
the range of 1 kΩ to 1 MΩ, and the time period is defined by
T = 1.1 x R1 x C1
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DCT100: Basic Engineering Skills
Electronic Circuit Lab Module
LED
1. LED (light emitting diode) is diode that allows an electric current to flow in
one direction, but essentially blocks it in the opposite direction (or can be
think as an electronic valve) PLUS, LED emit light that normal diode can
not.
Anode
Cathode
Figure 6: LED Symbol
LAB INSTRUMENTS
Digital Multimeter
1. Digital multimeter is one of the most versatile instruments, usually
containing three different meters in one.
a. The voltmeter measures the electrical potential difference across a
device (in volts)
b. An ammeter measures the amount of electrical current flowing
through a device (in amperes or amps)
c. An ohmmeter measures the electrical resistance of a device (in
ohms).
2. Digital multimeter gives an output in numbers, usually on a liquid crystal
display (LCD). A switched ranges multimeter is shown below.
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DCT100: Basic Engineering Skills
Electronic Circuit Lab Module
Figure 7: Switched Range Multimeter
3. The central knob has lots of positions and you must choose which one is
appropriate for the measurement you want to make. If the meter is switched
to 20 V DC, for example, then 20 V is the maximum voltage which can be
measured, this is sometimes called 20 V fsd, where fsd is short for full scale
deflection.
4. There are 2 types; AC and DC that can be measure using multimeter. DC
always indicated by
, whereas AC as
.
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DCT100: Basic Engineering Skills
Electronic Circuit Lab Module
Measuring Current
a) In figure 8 below show a circuit before and after connecting a
multimeter (in this case, multimeter work as an ammeter, measuring
current).
Figure 8: Measuring Current
b) To measure current, the circuit must be broken to allow the ammeter to
be connected in series. Thus, the ammeter must have a LOW internal
resistance.
Measuring Voltage
a) In figure 9 below, show a circuit before and after connecting a
multimeter (in this case, multimeter work as an voltmeter, measuring
voltage).
Figure 9: Measuring Voltage
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DCT100: Basic Engineering Skills
Electronic Circuit Lab Module
b) To measure potential difference (voltage), the circuit is not changed;
the voltmeter is connected in parallel and thus, the voltmeter must
have a HIGH resistance.
Measuring Resistance
a) An ohmmeter does not function with a circuit connected to a power
supply. To measure the resistance of a particular component, you must
take it out of the circuit altogether and test it separately, as shown in
figure 9 below.
Figure 10: Measuring Resistance
Digital Oscilloscope
1. Oscilloscope is a powerful lab instrument used for measuring electronic
signal such as DC or even AC signal for broad range of applications.
2. In this lab session, we will use digital oscilloscope from Tektronix, model
TDS 1002 with 2 channel input. In figure 11 below show the front panel of
this type of oscilloscope.
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DCT100: Basic Engineering Skills
Electronic Circuit Lab Module
Figure 11: Tektronix TDS 1002
3. To measure signal, probe must be used (figure 12) and have to be
connected to any channel (1 or 2) at the oscilloscope. For current lab
session, please verify that the probe attenuation is set to 1X.
Figure 12: Probe
Taking Simple Measurements
1. Connect probe to channel 1 port (labelled CH1) at the oscilloscope.
2. Connect the other end of the probe to PROBE COMP, and press
AUTOSET button.
3. The oscilloscope will automatically set the vertical and horizontal
settings.
4. The signal displayed on the oscilloscope now is pulse signal with
voltage amplitude 5 V and 1 kHz frequency.
5. You may try to adjust the vertical and horizontal controls by using
SEC/DIV and VOLTS/DIV knob to fit your needs.
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DCT100: Basic Engineering Skills
Electronic Circuit Lab Module
Power Supply Unit
1. For power supply usage for any experiment in this lab, we will use
TOPWARD – Dual Tracking DC Power Supply model 6303D.
2. In figure 13 below show the front panel for this instrument.
Figure 13: TOPWARD – Dual Tracking DC Power Supply Unit (6303D)
3. This device have the following features:
a) Twin power output with tracking function for automatic selection of
parallel or serial connection
b) Short-circuit protection against external input while providing
constant voltage and constant current
c) Allows serial or parallel connection with the same power supply
model
d) 5V/5A constant-voltage output
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DCT100: Basic Engineering Skills
Electronic Circuit Lab Module
4. For this lab session, we only interested in independent mode where only 1
output will be used, and also 5V/5A constant voltage output.
5. To use the power supply in independent mode, the following steps must
be taken:a) Set the TRACKING MODE switches on the front panel to IND.
b) Turn on the POWER switch.
c) Open the circuit between the + and the - output terminals. Turn the
voltage adjustment knob clockwise until you get the desired output
voltage rating.
d) Turn the current adjustment knob counterclockwise until you get the
minimum value.
e) Short the circuit between the + and the - output terminals.
Note
that the current rating of the shorting wire should be greater than or
equal to the required current.
f) Turn the current adjustment knob clockwise until the current
indicator on the front panel displays the required current rating.
g) Remove the shorting wire from the + and the - output terminals.
The power supply returns to the constant voltage mode and is
ready to use.
6. To use as fixed 5V/5A output, simply connect the positive (+ve) and
negative (-ve) probe to any device that need to power up. If short circuit
occur or the load exceeds 5 amperes, the red OVERLOAD LED lights up
and prevent damage to the device.
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DCT100: Basic Engineering Skills
Electronic Circuit Lab Module
Function Generator
Figure 14: INSTEK Function Generator (GFG-8020H)
1. Function generator provides square, triangle, sine and pulse waveform
over a frequency range from 0.2 Hz to 2 MHz.
2. To use the function generator for example to generate sinusoidal
waveform with frequency 1 MHz, the steps are:
i. Power up the function generator
ii. Connect the cable to the port output at front panel of the
function generator
iii. Press the sine waveform function switch
iv. Adjust the Multiplier so that 1 MHz sine wave is produced
v. You may try to connect the other end of the cable to
oscilloscope to see the waveform produced
12 | 2014 Universiti Malaysia Perlis
DCT100: Basic Engineering Skills
Electronic Circuit Lab Module
INTRODUCTION TO SOLDERING PROCESS
Vero board
1. Vero board has parallel strips of copper track on one side. The tracks are 0.1"
(2.54 mm) apart and there are holes every 0.1" (2.54 mm).
2. Vero board is used to make up permanent, soldered circuits. For large,
complex circuits it is usually best to use a printed circuit board (PCB).
3. Avoid handling Vero board that you are not planning to use immediately
because sweat from your hands will corrode the copper tracks and this will
make soldering difficult. If the copper looks dull, or you can clearly see finger
marks, clean the tracks with fine emery paper, a PCB rubber or a dry kitchen
scrub before you start soldering.
Figure 15 :
(a) Top View
(b) Bottom View
Placing components on Vero board
1. Components are placed on the non-copper side, and then the Vero board is
turned over to solder the component leads to the copper tracks. This means
that the tracks are out of sight under the board.
2. For most small circuits the best method is to very carefully place the chip
holder(s) in the correct position and solder in place. Then you can position all
the other components relative to the chip holder(s).
13 | 2014 Universiti Malaysia Perlis
DCT100: Basic Engineering Skills
Electronic Circuit Lab Module
Figure 16: Soldering side
Cutting Vero board tracks
1. Most Vero board circuits will need to have some tracks cut to break the
connection at that point. This is always necessary under ICs, except for the
rare cases where opposite pins must be connected. The tracks are cut with a
special track cutter tool or a 3mm drill bit.
2. Place the track cutter on the correct hole with moderate force. The aim is to
break the copper track, not drill a hole through the board! Inspect the cut
closely to ensure there is no fine thread of copper left across the break,
because even the tiniest piece will conduct.
SOLDERING TECHNIQUES
Soldering Concepts
Solder is used to hold two (or more) conductors in electrical contact with each
other, to encapsulate a joint, prevent oxidation of the joint, and provide minor
mechanical support for a connection. It is not used to make the electrical contact or to
provide the main mechanical support for a joint.
Solder is an alloy (mixture) of tin and lead, typically 60% tin and 40% lead. It
melts at a temperature of about 200°C. Coating a surface with solder is called ‘tinning’
because of the tin content of solder. Lead is poisonous and you should always wash
your hands after using solder.
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DCT100: Basic Engineering Skills
Electronic Circuit Lab Module
Figure 17: Solder
Solder for electronics use contains tiny cores of flux, like the wires inside a
mains flex. The flux is corrosive, like an acid, and it cleans the metal surfaces as the
solder melts. This is why you must melt the solder actually on the joint, not on the iron
tip. Without flux most joints would fail because metals quickly oxidize and the solder
itself will not flow properly onto a dirty, oxidized, metal surface.
Soldering Guide
A few safety precautions:
•
Never touch the element or tip of the soldering iron.
They are very hot (about 400 ⁰C) and will give you a nasty burn.
•
Always place the soldering iron in its original holder.
Never put it down on your workbench, even for a moment!
•
Remove all inflammable objects from the proximity of the hot soldering
iron.
•
Use suitable protective clothing to prevent the risk of burns associated
with molden solder.(PPE- Personal Protective Equipments)
•
Work in a well-ventilated area.
The smoke formed as you melt solder is mostly from the flux and quite irritating.
Avoid breathing it by keeping you head to the side of, not above your work.
•
Wash your hands after using solder.
Solder contains lead which is a poisonous metal.
Warning: Do not direct the Soldering Iron at people or inflammable objects!
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DCT100: Basic Engineering Skills
Electronic Circuit Lab Module
Preparing the soldering iron:
1. Warm-up.
Allow the soldering iron to reach adequate operating temperature of about
350 °C ± 50 °C.
(a) Common soldering iron
(b) A Temperature-controlled soldering iron
Figure 18: Soldering Iron
2. Wipe the tip of the iron in the metal wool or a wet sponge. This will clean
the tip.
3. Melt a little solder on the tip of the iron.
This is called 'tinning' and it will help the heat to flow from the iron's tip to the
joint. It only needs to be done when you plug in the iron, and occasionally while
soldering if you need to wipe the tip clean in the metal wool.
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DCT100: Basic Engineering Skills
Electronic Circuit Lab Module
You are now ready to start soldering:
1. Place the soldering iron tip against both the lead and the circuit board foil.
Heat both for 2 or 3 seconds.
Figure 19: Positioned the soldering iron
2. Then apply solder to the other side of the connection.
Important: Let the heated lead and the circuit board foil melt the solder.
Figure 20: Use solder
3. As the solder begins to melt, allow it to flow around the connection. Then
remove the solder and the iron and let the connection cool.
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DCT100: Basic Engineering Skills
Electronic Circuit Lab Module
Figure 21: Solder melt
Cleaning soldering iron from lead
When using lead free it will be experienced an increased oxidation in the
wettable area of the tip. These oxides must be removed regularly otherwise it will
make the tip completely unwettable and not usable anymore.
1. Push and turn the tip in the metal wool (see Figure 22).
Figure 22
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DCT100: Basic Engineering Skills
Electronic Circuit Lab Module
2. Soak the tip in flux which may improved the performance (see Figure 23).
Figure 23
Inspect the joint closely
It should look shiny and have a 'volcano' shape. If not, you will need to reheat it
and feed in a little more solder. This time ensure that both the lead and track are
heated fully before applying solder.
Figure 24: Comparison bad and good joins
19 | 2014 Universiti Malaysia Perlis
DCT100: Basic Engineering Skills
Electronic Circuit Lab Module
Desoldering
At some stage you will probably need to desolder a joint to remove or re-position a
wire or component. You can remove the solder with a desoldering pump or always
known as solder sucker.
1. Set the pump by pushing the spring-loaded plunger down until it locks.
2. Apply both the pump nozzle and the tip of your soldering iron to the joint.
3. Wait a second or two for the solder to melt.
4. Then press the button on the pump to release the plunger and suck the molten
solder into the tool.
5. Repeat if necessary to remove as much solder as possible.
6. The pump will need emptying occasionally by unscrewing the nozzle.
Figure 25: A desoldering pump or solder sucker.
20 | 2014 Universiti Malaysia Perlis
DCT100: Basic Engineering Skills
Electronic Circuit Lab Module
LAB ACTIVITIES 1
R3
R2
D1
Component
Item
Vero board
Resistors
10 kΩ
47 kΩ
470 Ω
Capacitors
100 µF
0.01 µF
Socket IC (8 pins)
555 Timer IC (8 pins)
LED
2 way header
Switch
Quantity
1
1
1
1
1
1
1
1
1
1
1
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DCT100: Basic Engineering Skills
Electronic Circuit Lab Module
Name :
Group :
Matrix No :
Date :
Program :
1.
By u s i n g
Vero
board
planning
sheet
below,
show the
component
placement and connection. Show only the parallel strips that will be used in
your soldering activities.
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22
. |. 2014
. . Universiti
. . . Malaysia
. . . .Perlis
. .
DCT100: Basic Engineering Skills
2.
Electronic Circuit Lab Module
By using the Vero board planning sheet from the previous question,
make a connection at the Vero board.
3.
What is the precaution should be taken?
4.
Explain how the circuit works, and suggest the use of this circuit in daily
applications.
5.
What is the time required for LED to turn on? Show the calculation
step.(Tips: Time Period, T = 1.1 × R1 × C1)
6.
If the circuit can’t function well, can you assume, which part will
contribute to the problem? List all. (e.g. No battery or misconnection)
7.
Measure the voltage across R1.
8.
Measure the voltage across R2.
9.
Measure the voltage across R3.
10. Measure the voltage across C1.
11. What is the value of current flow through R1?
12. What is the value of current flow through R2?
13. Predict, what is the current through D1? Explain why?
LAB ACTIVITIES 2
1. Modify circuit from lab activities 1 above to the circuit given below.
+9V
R3
Inspect the output using oscilloscope. Draw the output by scale on your answer
sheet. Give frequency, f, period, t, and amplitude, A of the resulting output.
23 | 2014 Universiti Malaysia Perlis