Download g). Based on the value of current and voltage

Engineering Skills ECT112 / PCT 112
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UNIVERSITI MALAYSIA PERLIS
COURSE
ENGINEERING SKILLS
NAME
COURSE
ECT112/3
CODE
LAB
PCT 112/3
NO.
LAB MODULE
BASIC ELECTRONIC CIRCUIT
LEVEL OF COMPLEXITY
1
2
3
4
5
6
KNOWLEDGE
COMPREHENSION
APPLICATION
ANALYSIS
EVALUATION
SYNTHESIS
√
√
√
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ENGINEERING CENTRE
CONTENT
Chapter 1
:
Introduction to Basic Electronic Theory
1.1 Voltage, Current and Power
1.1.1
Circuitry and Electricity
1.1.2
Types of Switches and Symbols
1.1.3
Types of Electronic Devices and Symbols
1.2 Ohm’s Law
1.3 Resistor and Potentiometer
1.4 Capacitor
1.5 Inductor
1.6 Transistor
1.7 Diodes
1.8 Light Emitting Diodes (LED)
1.9 555 Timer IC
Chapter 2
:
Basic Electronic Measuring Equipments
2.1 Breadboard
2.2 Multimeter
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CHAPTER 1
INTRODUCTION TO BASIC ELECTRONIC THEORY
1.1
VOLTAGE, CURRENT AND POWER
Electricity is the flow of electrons in a conductor and there are four quite intuitive quantities
help to characterize it. Voltage, current, resistance and power
The first is voltage. This term refers to the level of energy electrons have relative to some
reference point (often called ground in a circuit). The higher the voltage, the more energy
electrons have to do work as they travel through the circuit. In general, if two points are at a
different voltage relative to each other, electricity will flow from one to the other if they are
connected by something that conducts electricity.
The next quantity is current. This is an expression of how much charge is travelling through
the conductor per second. The unit of measurement for current is the Amp (A). You can see
that voltage and current are separate things: you can have a very small current at a very high
voltage, a huge current at a very high voltage and so on.
The next quantity is resistance. Resistance is an expression of the degree to which electron
flow will be impeded through a conductor. The unit is the Ohm ( ). In simple circuits
resistance determines the relation between voltage and current. At the extremes, a short piece
of wire will have a resistance of nearly zero Ohms, while an air gap (for example in an open
switch) has very large resistance (millions of Ohms). Intuitively a couple of relationships will
hold: in a conductor, a voltage difference between the two ends will cause a current to flow.
How much current will be determined by how much resistance the conductor offers. If there's
less resistance more current will flow. In fact, given a power source of high enough capacity,
if you half the resistance, you will double the current. Conversely, if you double the
resistance, you will half the current.
The final quantity is power. The unit of power is the Watt. It's an expression of the overall
energy consumed by a component. It is worked out by multiplying the voltage and the current
together - P = VI. For example if a motor was running at 12V and the current it was drawing
was 2A, the power it would be dissipating would be 24W.
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CIRCUITRY AND ELECTRICITY
For electricity to flow there needs to be a path that connects all the elements together. In the
diagram below, you can see how electricity can travel from the cell around in a loop through
the lamp and back to the cell again provided all the wires are in their proper places.
It should be noted that we show electricity travelling from the positive (+) side of the cell
around the circuit to the negative side. This is called conventional current. The slightly odd
thing about this is that the electrons that constitute electrical current are negatively charged
and actually travel in the opposite direction. The fact that we depict current travelling from
the positive to the negative is an historical accident. Fortunately unless you’re doing
something esoteric like semiconductor physics, this extra layer of complexity need never
worry you.
Lamp and Cell Circuit
Circuit diagrams provide a very efficient way to describe an electronic circuit. They use a
small set of symbols and conventions that need to be learned but the benefits of their form
over a more pictorial style are so definitive that they are used universally.
The circuit above can be diagrammed more efficiently. In order to illustrate this, here are
some symbols used to depict cells and lamps.
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Cell. This is often called a battery, but technically
a battery is multiple cells. This kind of cells is
rated at 1.5V.
Lamp. Lamps have voltage ratings like many
things. This rating indicates the voltage that the
lamp is designed to run at. It will be the highest
voltage the lamp can withstand without getting
too hot and burning out. Lamps may also state
their wattage – the power they consume. From
this and the re-arrangement of the equation for
power (I = P / V) the likely current consumed can
be calculated.
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1.1.2
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TYPES OF SWITCHES AND THEIR SYMBOLS
Push button. A normally open push button
conducts electricity when it is being pressed;
otherwise it's an open circuit.
Switch. Has an on and an off position. Conducts
when it's on and is an open circuit when off.
To see how devices combine, the cell and lamp circuit from above is recreated below with the
addition of a switch to turn the lamp on and off. The switch works, just like it looks like in the
diagram, by making or breaking a connection which completes the circuit or leaves it open.
An important observation is that it doesn't matter whether the switch is on the connection
from the positive side of the battery to the lamp or on the negative side. As long as it can
disrupt the circuit somewhere, it will work as a switch.
Lamp Circuit with switch
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TYPES OF ELECTRONIC DEVICES AND THEIR SYMBOLS
More sophisticated circuits require more complex components. Some more are presented
below.
Resistor. Device that resists the flow of electricity equally
in both directions. The two main important values
associated with resistors are their resistance and their
power rating. Resistance is measured in Ohms (Ω). An
Ohm is quite a small measurement for a lot of electrical
applications so the kΩ (or just k) is often used. 1k is
1000Ω. The other value is power. Resistors dissipate
energy so its important that exactly how much energy they
can dissipate is known. Most applications for resistors
require only fractional Watts of power.
Capacitor. Device that temporarily stores electric charge.
There are two main important values that characterize a
capacitor. The first is the capacitance - measured in
Farads. It turns out that a Farad is a huge amount, so
capacitors are often measured in micro-Farads ( F) or
pico-Farads (pF). The other important quantity is the rated
voltage. This value must never be exceeded in a circuit.
Diode. Semiconductor device that conducts electricity in
only one direction. Exist in different varieties. Zener
diodes permit conduction in the reverse direction only
when the reverse voltage exceeds a certain amount. TVS
diodes are like Zeners except capable of much higher
currents.
Potentiometer. A variable resistor. Often connected as a
voltage divider to create variable voltages when used as a
rotational position sensor.
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LED. Light Emitting Diode. Common indicator in
electronics. Produces a lot of light for not much current.
But will very quickly (perhaps instantaneously) burn out if
too much current is allowed to flow in it. Like any diode,
has very low resistance in its conducting direction, so a
resistor in series with it to limit the current is usually a
requirement.
Photoresistor. A resistor with the useful property that its
resistance changes depending on how much light it is
receiving. Photoresistors can have a quite impressive
resistance range, for example from a few million ohms (M
) in the dark to under a hundred ohms in bright light. One
possible disadvantage is that their reaction time is in the
order of 100ms - too slow for many applications.
Supply. The Supply symbol is a diagrammatical shortcut
used to indicate that the wire is connected back to the
power. It saves having to draw a wire from the power
source to every point in the circuit that uses it.
Ground. The Ground symbol is a diagrammatical shortcut
of the same kind as the supply. It is used to indicate that
whatever is connected should be considered to be
connected to the Ground of the power supply.
Motor. Conventional DC motor. When deciding how to
control a given motor there are several important issues:
what voltage was the motor designed to work with and
how much current does it draw when it's running.
Commonly available DC motors can draw anything from
10mA to more than 100A. Motor selection is a huge topic.
You'll need to consider voltage, power consumption,
RPM,
torque,
start
and
stall
requirements, heat dissipation, etc.
current,
mounting
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Coil. Can represent a relay, a pneumatic or hydraulic valve
or solenoid. The principle is the same in all cases: when
the coil is energized, it creates a magnetic field which
attracts some metal part. Some coils can heat up if left on
for a long time so they are often given a duty-cycle
meaning that their designer specifies whether they can be
left on indefinitely or whether they're designed only to
switch on and off again rarely.
Battery. The idea is that there is one wide and narrow line
(cell) for each cell in the battery. When it becomes
onerous to draw all the cells, an ellipsis is added before the
last cell. The common rectangular 9V battery we buy at
the store is in fact 6 1.5V cells stacked together.
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1.2
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OHM’S LAW
Ohm’s Law is about relationship between voltage, current and resistance. This relationship is
a mathematical one and it can be expressed very simply by way of Ohm's Law.
Ohm's Law observes that in a simple resistive circuit, voltage (V), resistance (R) and current
(I) are related in the following way:
V = IR
This expression can be rearranged algebraically to find other ways to use it as follows:
I = V / R (dividing both sides by R)
R = V / I (dividing both sides by I)
The idea is that if two quantities are know, the third one can be work out using one of the
equations.
In the circuit fragment above, a resistor is connected between a 5V supply and ground (0V).
We can use this to check the assertions we made earlier about the effects of doubling the
resistance on a circuit and so on. If the resistor's value is 10Ω, we can work out what current
will flow as follows. We know the voltage (5V) and the resistance (10Ω), so the form of the
equation we need is:
I=V/R
Substituting our values in we have:
I = 5 / 10
The current I in our circuit will be 0.5A which can also be expressed as 500mA.
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Now if we were to double the resistance (to 20Ω), let's confirm that we halve the current:
I=V/R
Substituting our values in we have:
I = 5 / 20
The current I in our new circuit will be 0.25A (or 250mA), which is indeed half the previous
current.
1.3
RESISTOR AND POTENTIOMETER
Resistors are two-terminal devices that restrict, or resist, the flow of current. The larger the
resistor the less current can flow through it for a given voltage as demonstrated by Ohm’s
law:
V= I*R
Electrons flowing through a resistor collide with material in the resistor body, and it is these
collisions that cause electrical resistance. These collisions cause energy to be dissipated in the
form of heat or light (as in a toaster or light bulb).
Resistance is measured in Ohms, and an ohm is defined by the amount of resistance that
causes 1A of current to flow from a 1V source.
The amount of power (in Watts) dissipated in a resistor can be calculated using the equation
P= I x V = I2R.
A resistor that can dissipate about 5 Watts of power would be about the size of a writing pen,
and a resistor that can only dissipate 1/8 Watt is about the size of a grain of rice. If a resistor is
placed in a circuit where it must dissipate more that its intended power, it will simply melt.
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1.3.1 What do resistors do?
Resistors limit current. In a typical application, a resistor is connected in series with an LED:
Enough current flows to make the LED light up, but not so much that the LED is damaged.
The 'box' symbol for a fixed resistor is popular in the UK and Europe. A 'zig-zag' symbol is
used in America and Japan:
Resistors are used with transducers to make sensor subsystems. Transducers are electronic
components which convert energy from one form into another, where one of the forms of
energy is electrical. A light dependent resistor, or LDR, is an example of an input
transducer. Changes in the brightness of the light shining onto the surface of the LDR result
in changes in its resistance. As will be explained later, an input transducer is most often
connected along with a resistor to make a circuit called a potential divider. In this case, the
output of the potential divider will be a voltage signal which reflects changes in illumination.
Microphones and switches are input transducers. Output transducers include loudspeakers,
filament lamps and LEDs.
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In other circuits, resistors are used to direct current flow to particular parts of the circuit, or
may be used to determine the voltage gain of an amplifier. Resistors are used with capacitors
to introduce time delays.
How can the value of a resistor be worked out from the colours of the bands? Each colour
represents a number according to the following scheme:
Number
Colour
0
black
1
brown
2
red
3
orange
4
yellow
5
green
6
blue
7
violet
8
grey
9
white
The first band on a resistor is interpreted as the FIRST DIGIT of the resistor value. For the
resistor shown below, the first band is yellow, so the first digit is 4:
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The second band gives the SECOND DIGIT. This is a violet band, making the second digit 7.
The third band is called the MULTIPLIER and is not interpreted in quite the same way. The
multiplier tells you how many noughts you should write after the digits you already have. A
red band tells you to add 2 noughts. The value of this resistor is therefore 4 7 0 0 ohms, that
is, 4 700
, or 4.7
. Work through this example again to confirm that you understand
how to apply the colour code given by the first three bands.
The remaining band is called the TOLERANCE band. This indicates the percentage accuracy
of the resistor value. Most carbon film resistors have a gold-coloured tolerance band,
indicating that the actual resistance value is with + or - 5% of the nominal value. Other
tolerance colours are:
Tolerance
Colour
±1%
brown
±2%
red
±5%
gold
±10%
silver
When you want to read off a resistor value, look for the tolerance band, usually gold, and hold
the resistor with the tolerance band at its right hand end. Reading resistor values quickly and
accurately isn't difficult, but it does take practice.
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1.3.2 Current limiting
Example :
Objective :
To calculate a value for the resistor used in series with an LED.
A typical LED requires a current of 10 mA and has a voltage of 2 V across it when it is
working. The power supply for the circuit is 9 V. What is the voltage across resistor R1? The
answer is 9-2=7 V. (The voltages across components in series must add up to the power
supply voltage.)
You now have two bits of information about R1: the current flowing is 10 mA, and the
voltage across R1 is 7 V. To calculate the resistance value, use the formula:
Substitute values for V and I:
The formula works with the fundamental units of resistance, voltage and current, that is,
ohms, volts and amps. In this case, 10 mA had to be converted into amps, 0.01 A, before
substitution.
If a value for current in mA is substituted, the resistance value is given in kΩ:
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The calculated value for R1 is 700 Ω. What are the nearest E12/E24 values? Resistors of 680
Ω, 750 Ω and 820 Ω are available. 680 Ω is the obvious choice. This would allow a current
slightly greater than 10 mA to flow. Most LEDs are undamaged by currents of up to 20 mA.
1.3.3 Resistors in series and parallel
In a series circuit, the current flowing is the same at all points. The circuit diagram shows two
resistors connected in series with a 6 V battery:
Resistors in series
It doesn't matter where in the circuit the current is measured, the result will be the same. The
total resistance is given by:
In this circuit, Rtotal=1+1=2 kΩ. What will be the current flowing? The formula is:
Substituting:
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Notice that the current value is in mA when the resistor value is substituted in kΩ.
The same current, 3 mA, flows through each of the two resistors. What is the voltage across
R1? The formula is:
Substituting:
What will be the voltage across R2? This will also be 3 V. It is important to point out that the
sum of the voltages across the two resistors is equal to the power supply voltage.
The next circuit shows two resistors connected in parallel to a 6 V battery:
Resistors in parallel
Parallel circuits always provide alternative pathways for current flow. The total resistance is
calculated from:
𝑅
𝑡𝑜𝑡𝑎𝑙=
𝑅1 𝑅2
𝑅1 +𝑅2
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This is called the product over sum formula and works for any two resistors in parallel. An
alternative formula is:
This formula can be extended to work for more than two resistors in parallel, but lends itself
less easily to mental arithmetic. Both formulas are correct.
What is the total resistance in this circuit?
The current can be calculated from:
How does this current compare with the current for the series circuit? It's more. This is
sensible. Connecting resistors in parallel provides alternative pathways and makes it easier for
current to flow. How much current flows through each resistor? Because they have equal
values, the current divides, with 6 mA flowing through R1, and 6 mA through R2.
To complete the picture, the voltage across R1 can be calculated as:
This is the same as the power supply voltage. The top end of R1 is connected to the positive
terminal of the battery, while the bottom end of R1 is connected to the negative terminal of
the battery. With no other components in the way, it follows that the voltage across R1 must
be 6 V. What is the voltage across R2? By the same reasoning, this is also 6 V.
1.3.4 Power rating
When current flows through a resistance, electrical energy is converted into heat. This is
obvious in an electric torch where the lamp filament heats up and glows white hot. Although
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the result may be less evident or imperceptible, exactly the same process of energy conversion
goes on when current flows through any electronic component.
The power output of a lamp, resistor, or other component, is defined as the rate of change of
electrical energy to heat, light, or some other form of energy. Power is measured in watts, W,
or milliwatts, mW, and can be calculated from:
Where P is power.
What is the power output of a resistor when the voltage across it is 6 V, and the current
flowing through it is 100 mA?
0.6 W of heat are generated in this resistor. To prevent overheating, it must be possible for
heat to be lost, or dissipated, to the surroundings at the same rate.
A resistor's ability to lose heat depends to a large extent upon its surface area. A small resistor
with a limited surface area cannot dissipate (=lose) heat quickly and is likely to overheat if
large currents are passed. Larger resistors dissipate heat more effectively.
1.3.5 POTENTIOMETER
Potentiometers (or pots, as we’ll call them) are incredibly versatile devices. They can act as
voltage dividers, or as variable resistors. Pots come in all sorts of shapes and sizes. The most
common type we use in pedals and amps are usually of the 24mm or 16mm round metal can
type. There are also multi-gang pots (which stack multiple independent pots on one shaft),
slider pots, trimmer pots, etc.
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In the case of a standard pot, as shown above, we have a round case with three connectors and
a shaft that turns. Here’s what it looks like in a schematic:
One of the first (and most common) mistakes in using potentiometers is misreading the front
versus the back and the lug numbers.
The pot has three lugs and by convention they are numbered 1,2, and 3. Pin 2 is called the
wiper.
These numbers map to the schematic symbol like this:
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Pots come in different tapers. The taper defines how the resistance of the pot changes in
relationship to turning the shaft.

Linear Taper: The simplest form. The rotation of the knob directly corresponds to the
resistance change in linear fashion.

Audio/Logarithmic Taper: This taper compensates for how the human ear perceives
changes in volume. It has a different curve—the resistance change as you turn the knob is not
linear. Note that audio taper is the same thing as logarithmic (or “log” as you will sometimes
see it). Just different names.

Reverse Audio/Log Taper : This has the same curve as the audio taper, but in reverse.
The following diagram shows the relation of resistance change as you turn the pot knob
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Potentiometers are rated by their total resistance. The resistance between the center terminal and the
two other terminals always adds up to the total resistance rating of the potentiometer.
Here are a few other rambling thoughts to keep in mind about potentiometers:

Potentiometers come in a wide variety of shapes and sizes. With a little hunting around in
stores or on the Internet, you should be able to find the perfect potentiometer for every need.

Some potentiometers are very small and can be adjusted only by the use of a tiny screwdriver.
This type of pot is called a trim pot, designed to make occasional fine-tuning adjustments to
your circuits.

Some potentiometers have switches incorporated into them so that when you turn the knob all
the way to one side or pull the knob out, the switch operates to either open or close the circuit.

When the wiper reaches one end of the resistor or the other, the resistance between the center
terminal and the terminal on that end is essentially zero. Keep this point in mind when you're
designing circuits. To avoid circuit paths with no resistance, it's common to put a small
resistor in series with a potentiometer.

In some potentiometers, the resistance varies evenly as you turn the dial. For example, if the
total resistance is 10 kΩ, the resistance at the halfway mark is 5 kΩ, and the resistance at the
one-quarter mark is 2.5 kΩ. This type of potentiometer is called a linear taper potentiometer
because the resistance change is linear.
Many potentiometers, however, aren't linear. For example, potentiometers designed for audio
applications usually have a logarithmic taper, which means that the resistance doesn't vary
evenly as you move the dial.

Some variable resistors have only two terminals: one on an end of the resistor itself, the other
attached to the wiper. This type of variable resistor is properly called a rheostat, but most
people use the term potentiometer or pot to refer to both two- and three-terminal variable
resistors.
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1.4 CAPACITOR
The two charged plates forms a device for concentrating and storing an electric charge. We
refer to this device as a capacitor and its ability to store a charge is called capacitance (also
known as condenser). Put simply, capacitance is a measure of the ability of a capacitor to
store an electric charge when a potential difference is applied. Thus a large capacitance will
store a larger charge for a given applied voltage.
A simple parallel plate capacitor is shown in fig.1.In practice and although air-spaced
capacitors are used in some radio frequency (RF) applications, the space between the plates of
most capacitors is filled with an insulating material, known as a dielectric. Typical dielectric
materials are polyester, mica, or ceramic. Note that a dielectric material must be a good
insulator (it must not conduct electric current) and also that it must be able to retain its
insulating properties when a high voltage is applied to it.
Parallel Plate Capacitor
Charge Plot, Q, against potential difference, V, for a capacitor arrive at a straight line law.
The slope of this graph is an indication of the capacitance, C, of the capacitor, as shown in
Fig.1. From Fig.2, the capacitance is directly proportional to the slope of the graph, as
follows:
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Fig.2 - Charge vs Voltage
In symbols this relationship is simply
C = Q/V
where the charge, Q, is measured in coulombs (C) and the potential difference, V, is measured
in volts (V).The unit of capacitance is the Farad (F)
Where one Farad of capacitance produces a charge of one Coulomb when a potential
difference of one volt is applied. Note that, in practice, the Farad is a very large unit and we
therefore often deal with sub-multiples of the basic unit such as microFarad (1 × 10-6F), nF (1
× 10-9F), and pF (1 × 10-12F).
Factors Determining Capacitance
The capacitance of a capacitor depends upon the physical dimensions of the capacitor (i.e., the
size of the plates and the separation between them) and the dielectric material between the
plates. The capacitance of a conventional parallel plate capacitor is given by:
where C is the capacitance (in Farads), E0 is the permittivity of free space, Er is the relative
permittivity (or dielectric constant) of the dielectric medium between the plates), A is the area
of the plates (in square metres), and d is the separation between the plates (in meters). The
permittivity of free space, E0, is 8·854 × 10-12 F/m.
In order to increase the capacitance of a capacitor, many practical components employ
interleaved multiple plates (see Fig. 3) in which case the capacitance is then given by:
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where C is the capacitance (in Farads), E0 is the permittivity of free space, Er is the relative
permittivity of the dielectric medium between the plates), n is the number of plates, A is the
area of the plates (in square metres), and d is the separation between the plates (in metres).
Capacitors in Practical
Inside capacitor
The specifications for a capacitor usually include the value of capacitance (expressed in
microF, nF, or pF), the voltage rating (i.e. the maximum voltage which can be continuously
applied to the capacitor under a given set of conditions), and the accuracy or tolerance (quoted
as the maximum permissible percentage deviation from the marked value).
Other practical considerations when selecting capacitors for use in a particular application
include temperature coefficient, leakage current, stability and ambient temperature range.
Electrolytic capacitors require the application of a DC polarising voltage in order to work
properly.
This voltage must be applied with the correct polarity (invariably this is clearly marked on the
case of the capacitor) with a positive (+) sign or negative (–) sign or a coloured stripe or other
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marking. Failure to observe the correct polarity can result in over-heating, leakage, and even a
risk of explosion!
The typical specifications for some common types of capacitor are shown in table below..
Typical Capacitor Specifications
Working voltages are related to operating Temperatures and capacitors must be de-rated at
high temperatures . Where reliability is important capacitors should be operated at well below
their nominal maximum working voltages. Where the voltage rating is expressed in terms of a
direct voltage (e.g. 250V DC) unless otherwise stated, this is related to the maximum working
temperature.
It is, however, always wise to operate capacitors with a considerable margin for safety which
also helps to ensure long term reliability. The working DC voltage of a capacitor should be no
more than about 50% to 60% of its rated DC voltage.Where an AC voltage rating is specified
this is normally for sinusoidal operation.
Performance will not be significantly affected at low frequencies (up to 100kHz, or so) but,
above this, or when non-sinusoidal (e.g. pulse) waveforms are involved the capacitor must be
de-rated in order to minimise dielectric losses that can produce internal heating and lack of
stability.
Special care must be exercised when dealing with high-voltage circuits as large value
electrolytic and metallised film capacitors can retain an appreciable charge for some
considerable time. In the case of components operating at high voltages, a carbon film bleed
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resistor (of typically 1M ohm 0·5W) is often connected in parallel with the capacitor to
provide a discharge path.
Some typical small capacitors are shown in Photos below.
Types of Capacitors
Capacitor symbols
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Capacitor Markings and Colour Codes
The vast majority of capacitors employ written markings which indicate their values, working
voltages, and tolerance. The most usual method of marking resin dipped polyester (and other)
types of capacitor involves quoting the value (in ?F, nF or pF), the tolerance (often either 10%
or 20%), and the working voltage (using _ and ~ to indicate DC and AC respectively). Several
manufacturers use two separate lines for their capacitor markings and these have the
following meanings:
First line: capacitance (in pF or microF) and tolerance (K=10%, M=20%)
Second line: rated DC voltage and code for the dielectric material.
A three-digit code is sometimes used to mark monolithic ceramic capacitors.
The first two digits correspond to the first two digits of the value whilst the third digit is a
multiplier that gives the number of zeroes to be added to give the value in pF.
The colour code shown in Fig.4 is used for some small ceramic and polyester types of
capacitor. Note, however, that this colour code is not as universal as that used for resistors and
that the values are marked in pF (not F).
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Capacitor color code chart
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1.5 INDUCTORS
Inductance is typified by the behavior of a coil of wire in resisting any change of electric
current through the coil.
Arising from Faraday's law, the inductance L may be defined in terms of the emf generated
to oppose a given change in current:
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1.6 TRANSISTOR
Transistors amplify current, for example they can be used to amplify the small output current
from a logic IC so that it can operate a lamp, relay or other high current device. In many
circuits a resistor is used to convert the changing current to a changing voltage, so the
transistor is being used to amplify voltage.
A transistor may be used as a switch (either fully on with maximum current, or fully off with
no current) and as an amplifier (always partly on).
The amount of current amplification is called the current gain, symbol hFE.
1.6.1
TYPES OF TRANSISTOR
There are two types of standard transistors, NPN and
PNP, with different circuit symbols. The letters refer
to the layers of semiconductor material used to make
the transistor. Most transistors used today are NPN
because this is the easiest type to make from silicon. If
you are new to electronics it is best to start by learning
Transistor circuit symbols
how to use NPN transistors.
The
leads
are
labelled
base
(B),
collector
(C)
and
emitter
(E).
These terms refer to the internal operation of a transistor but they are not much help in
understanding how a transistor is used, so just treat them as labels.
A Darlington pair is two transistors connected together to give a very high current gain.
In addition to standard (bipolar junction) transistors, there are field-effect transistors which
are usually referred to as FETs. They have different circuit symbols and properties and they
are not (yet) covered by this page.
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1.7 DIODES
Function
Diodes allow electricity to flow in only one direction. The arrow of the circuit symbol shows
the direction in which the current can flow. Diodes are the electrical version of a valve and
early diodes were actually called valves.
Forward Voltage Drop
Electricity uses up a little energy pushing its way through the diode, rather like a person
pushing through a door with a spring. This means that there is a small voltage across a
conducting diode, it is called the forward voltage drop and is about 0.7V for all normal
diodes which are made from silicon. The forward voltage drop of a diode is almost constant
whatever the current passing through the diode so they have a very steep characteristic
(current-voltage graph).
Reverse Voltage
When a reverse voltage is applied a perfect diode does not conduct, but all real diodes leak a
very tiny current of a few µA or less. This can be ignored in most circuits because it will be
very much smaller than the current flowing in the forward direction. However, all diodes have
a maximum reverse voltage (usually 50V or more) and if this is exceeded the diode will fail
and pass a large current in the reverse direction, this is called breakdown.
Ordinary diodes can be split into two types: Signal diodes which pass small currents of
100mA or less and Rectifier diodes which can pass large currents. In addition there are LEDs
(which have their own page) and Zener diodes.
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1.8 LIGHT EMITTING DIODE (LED)
LEDs emit light when an electric current passes through them.
Connecting and soldering
LEDs must be connected the correct way round, the diagram may be
labelled a or + for anode and k or - for cathode. The cathode is the short
lead and there may be a slight flat on the body of round LEDs. If you
can see inside the LED the cathode is the larger electrode (but this is not an official
identification method).
LEDs can be damaged by heat when soldering, but the risk is small unless you are very slow.
No special precautions are needed for soldering most LEDs.
Testing an LED
Never
connect
an
LED
directly
to
a
battery
or
power
supply.
It will be destroyed almost instantly because too much current will pass through and burn it
out.
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LEDs must have a resistor in series to limit the current to a safe value, for quick testing
purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less.
Remember to connect the LED the correct way round.
1.9 555 Timer IC
Actual Pin Arrangement
The 8-pin 555 timer must be one of the most useful ICs ever made and it is used in
many projects. With just a few external components it can be used to build many circuits, not
all of them involve timing.
A popular version is the NE555 and this is suitable in most cases where a '555 timer'
is specified. The 556 is a dual version of the 555 housed in a 14-pin package, the two timers
(A and B) share the same power supply pins. The circuit diagrams on this page show a 555,
but they could all be adapted to use one half of a 556.
Low power versions of the 555 are made, such as the ICM7555, but these should only
be used when specified (to increase battery life) because their maximum output current of
about 20mA (with a 9V supply) is too low for many standard 555 circuits. The ICM7555 has
the same pin arrangement as a standard 555.
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The circuit symbol for a 555 (and 556) is a box with the pins arranged to suit the
circuit diagram: for example 555 pin 8 at the top for the +Vs supply, 555 pin 3 output on the
right. Usually just the pin numbers are used and they are not labelled with their function.
The 555 and 556 can be used with a supply voltage (Vs) in the range 4.5 to 15V (18V
absolute maximum).
Standard 555 and 556 ICs create a significant 'glitch' on the supply when their output
changes state. This is rarely a problem in simple circuits with no other ICs, but in more
complex circuits a smoothing capacitor (eg 100µF) should be connected across the +Vs and
0V supply near the 555 or 556.
The input and output pin functions are described briefly below and there are fuller
explanations covering the various circuits:

Astable - producing a square wave

Monostable - producing a single pulse when triggered

Bistable - a simple memory which can be set and reset

Buffer - an inverting buffer (Schmitt trigger
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CHAPTER 2
BASIC ELECTRONIC MEASUREMENT EQUIPMENTS
As a prerequisite for this course on basic Electronics, knowledge of general principles of
electricity & magnetism is assumed. The students will attempt here to learn basic principles
of electronics by the scheme “Learning by Doing”.
In this course, the principles of operation of the different electronic devices, measuring
instruments and circuits will be discussed and a set of simulated demonstration experiments
are included wherever possible for the learner to perform these simple experiments on
his/her own and learn the concepts by “doing.” This will enable the learner to gain greater
confidence at the end in the principles and working of electronic devices and circuits.
Before proceeding further, it is important to understand how the different circuits can be
built and tested.
Measuring Instruments:
Power Supply

Multimeter

Voltage Sources & Current Sources

Oscilloscopes

Function Generators
In order to use the Measuring Instruments, a circuit need to be set up using a “Bread Board”.
Invariably a “bread-board” is used in a laboratory for constructing the different circuits and
testing them. This is very useful since we do not have to solder the different components.
Soldering can be very time consuming. Further, we can reuse the components again and
again, since they are not cut and soldered.
Engineering Skills ECT112 / PCT 112
2.1
Lab Module
BREADBOARD
Uses of Breadboard
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.
The photograph shows a typical small breadboard which is suitable for beginners building
simple circuits with one or two ICs (chips).
Figure: Breadboard
Connections on Breadboard
Breadboards have many tiny sockets (called 'holes') arranged on a 0.1" grid. The leads of most
components can be pushed straight into the holes. ICs are inserted across the central gap with
their notch or dot to the left.
Wire links can be made with single-core plastic-coated wire of 0.6mm diameter (the standard
size). Stranded wire is not suitable because it will crumple when pushed into a hole and it
may damage the board if strands break off.
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The diagram shows how the
breadboard holes are
connected:
The top and bottom rows are
linked horizontally all the way
across as shown by the red and
black lines on the diagram. The
power supply is connected to
these rows, + at the top and 0V
Figure 1: Connections on Breadboard
(zero volts) at the bottom.
The other holes are linked vertically in blocks of 5 with no link across the centre as shown by
the blue lines on the diagram. Notice there are separate blocks of connections to each pin of
ICs.
Large Breadboards
On larger breadboards there may be a break halfway along the top and bottom power supply
rows. It is a good idea to link across the gap before you start to build a circuit, otherwise you
may forget and part of your circuit will have no power!
Wiring Symbols
There are many different representations for basic wiring symbols, and these are the most
common.
The conventionals use for wires crossing and joining are marked with a star (*) - the others
are a small sample of those in common use, but are fairly representative.
Example 2: Building a Circuit on Breadboard
Converting a circuit diagram to a breadboard layout is not straightforward because the
arrangement of components on breadboard will look quite different from the circuit diagram.
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When putting parts on breadboard student must concentrate on their connections, not their
positions on the circuit diagram. The IC (chip) is a good starting point so place it in the centre
of the breadboard and work round it pin by pin, putting in all the connections and components
for each pin in turn.
The best way to explain this is
by example, so the process of
building this 555 timer circuit on
breadboard is listed step-by-step
below.
The circuit is a monostable
which means it will turn on the
LED for about 5 seconds when
the 'trigger' button is pressed.
The time period is determined
by R1 and C1 and you may wish
Monostable Circuit Diagram
to try changing their values. R1 should be in the range 1kΩ to 1MΩ.
Time Period, T = 1.1 × R1 × C1
IC pin numbers
IC pins are numbered anti-clockwise around the IC starting near the notch or dot. The
diagram shows the numbering for 8-pin and 14-pin ICs, but the principle is the same for all
sizes.
Components without suitable leads
Some components such as switches and variable
resistors do not have suitable leads of their own so
you must solder some on yourself. Use single-core plastic-coated wire of 0.6mm diameter
(the standard size). Stranded wire is not suitable because it will crumple when pushed into a
hole and it may damage the board if strands break off.
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Building the example circuit
Begin by carefully insert the 555 IC in the centre of the breadboard with its notch or dot to the
left.
Then deal with each pin of the 555:
1.
Connect a wire (black) to 0V.
2.
Connect the 10k resistor to +9V.
Connect a push switch to 0V (you will need to solder leads onto the switch)
3.
Connect the 470 resistor to an used block of 5 holes, then...
Connect an LED (any colour) from that block to 0V (short lead to 0V).
4.
Connect a wire (red) to +9V.
5.
Connect the 0.01µF capacitor to 0V.
You will probably find that its leads are too short to connect directly, so put in a wire link to
an unused block of holes and connect to that.
6.
Connect the 100µF capacitor to 0V (+ lead to pin 6).
Connect a wire (blue) to pin 7.
7.
Connect 47k resistor to +9V.
Check: there should be a wire already connected to pin 6.
8.
Connect a wire (red) to +9V.
Finally:
Check all the connections carefully.

Check that parts are the correct way round (LED and 100µF capacitor).

Check that no leads are touching (unless they connect to the same block).

Connect the breadboard to a 9V supply and press the push switch to test the circuit.
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If your circuit does not work disconnect (or switch off) the power supply and very carefully
re-check every connection against the circuit diagram.
2.2
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- 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 -ohms and any with -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.
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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
analogue 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 2.2
(c).
Figure 2.2 (a)
1.) Indicator Zero Connector
2.) Indicator Pointer
3.) Indicator Scale
4.) Continuity Indicating LED ( CONTINUITY )
5.) Range Selector Switch knob
6.) 0-ohms adjusting knob /0- centering meter (NULL meter) adjusting knob
7.) Measuring Terminal +
8.) Measurin Terminal - COM
9.) Series Terminal Capacitor
10.) Panel
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11.) Rear Case
Figure 2.2 (b)
1.) Resistance (OHMS) scale
2.) DCV, A scale and ACV scale
(10V or more)
3.) 0-centernig (NULL) +/- DCV scale
4.) ACV 2.5 (AC 2.5V) exclusive scale
5.) Transistor DC amplification factor
(hFE) scale
6.) 1.5 baterry test (BATT 1.5V)
7.) OHMS range terminal to terminal current
(Li) scale)
8.) OHMS range terminal to terminal voltage
(LV) scale
9.) Decibel (dB) scale
10.) Continuity Indicating LED
11.0 Mirror: To obtain most accurate readings,
the mirror is deviced to make operator eyes, the indicator pointer, and the indicator pointer
reflexes to the mirror put together in line.
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Figure 2.2 (c): Real Wiring Diagram for Illustration
Figure 2.2 (d): Names of Component
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.
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vi. Before starting the measurement, make sure that the function or range properly set in
accordance with the measurement.
vii. Be sure to disconnect the the test pins from the circuit when changing the function or
range.
viii. For details, please refer instruction manual.
b) Preparation for Measurement
i. Adjustment of meter zero position
Turn the zero position adjuster so that the pointer may align right to the zero position.
ii. Range selection: Select a range proper for the item to be measured. Set the range selector
knob accordingly.
c) Measuring DC Voltage
i. Set the range selector knob to an appropriate DCV range.
ii. Apply the black test pin to the minus potential of measured circuit and the red test pin to
the plus potential as in Figure 2.2 (e).
iii. Read the move of the pointer by V and A scale.
Figure 2.2 (e)
d) Measuring DC Voltage (NULL)
i. Set the range selector knob to an appropriate range.
ii. Turn the adjuster so that the pointer may align exactly to 0 by DCV scale.
iii. 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 2.2 (f).
iv. Read the move of the pointer by DCV scale.
Engineering Skills ECT112 / PCT 112
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Figure 2.2 (f)
e) Measuring AC Voltage.
i. Turn the range selector knob to an appropriate ACV range.
ii. Apply the test leads to measured circuit as in Figure 2.2 (g).
iii. 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 2.2 (g)
f) Measuring DC Current
i. Connect the meter in series with the load.
ii. Turn the range selector knob to an appropriate DCA range.
iii. 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 2.2 (h).
iv. Read the move of the pointer by V and A scale.
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Figure 2.2 (h)
g) Measuring Resistance (Ω)
Precaution: Do not measure a resistance in a circuit where a voltage is present.
i. Turn the range selector knob to an appropriate Ω range.
ii. Short the red and black test pins and turn the 0 Ω adjuster so that the pointer may align
exactly to 0. (If the pointer fails to swing up to 0 Ωeven when the 0 Ω adjuster is turned
clockwise fully, replace the internal battery with a fresh one.)
iii. Apply the test pin to measured resistance as in Figure 2.2 (i).
iv. Read the move of the pointer by Ω scale.
v. Note: The polarity of (+) and (-) turns reverse to that of the test leads when
measurement is done in Ω range.
Figure 2.2 (i)
Engineering Skills ECT112 / PCT 112
2.3
Lab Module
Power Supply
Power supplies are amongst the most popular pieces of electronic test equipment.
This isn't surprising, as controlled electrical energy is used in a tremendous number of ways.
In this guide, we'll look at a variety of different types of power supplies, their controls, how
they operate, and some examples of their application. A power supply could broadly be
defined to be anything that supplies power, such as a hydroelectric dam, an internal
combustion engine, or a hydraulic pump.
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UNIVERSITI MALAYSIA PERLIS
COURSE
ENGINEERING SKILLS
NAME
COURSE
ECT112/3
CODE
LAB
PCT 112/3
NO.
LAB TASK
BASIC ELECTRONIC CIRCUIT
LEVEL OF COMPLEXITY
1
2
3
4
5
6
KNOWLEDGE
COMPREHENSION
APPLICATION
ANALYSIS
EVALUATION
SYNTHESIS
√
√
√
Engineering Skills ECT112 / PCT 112
Lab Module
Name : ____________________________________________________ Group :____________
Course :__________________________________________ Date: _________________________
Lab Task 1 : Resistor and LED
In electronic circuits you encounter quite often the problem of too much current. Therefore you
need a component that is able to regulate the current and this can be done by resistors. To
experience the effect of a resistor, set up the circuit shown. When you press the pushbutton
switch, the LED lights up with normal brightness.[Never connect LED directly to power
supply, LED will damaged].
I
R
5V
i. Set the voltage at power supply to 5V d.c.
ii. Construct the schematic diagram shown in Fig. 1.0 on breadboard.
iii. Begin with the resistor value of 47 kΩ.
iv. Measure the value of currentI, resistor voltage and LED voltage for each resistor using
digital or analog multi meter.
v. Select the brightness of LED within the specified range (scale 1-5).
vi. Repeat this experiment using the different value of resistor.
D. C.
Resistor
LED Voltage,
Voltage
value, (R)
(𝑉𝐿𝐸𝐷 )
(V)
5V
47
5V
kΩkΩ
0.47
kΩ
5V
Type
here.
16 equation
kΩ
5V
3.4 kΩ
5V
1 kΩ
Resistor Voltage,
Current I,
Led brightness (write within
(𝑉𝑅 )
(A)
the scale 1-5).
Engineering Skills ECT112 / PCT 112
vii.
Lab Module
Based from the results obtained, write your conclusions.
a). The relation between brightness and resistor.
____________________________________________________________________
____________________________________________________________________
b). The relation between current and resistor.
____________________________________________________________________
____________________________________________________________________
c). The relation between voltage and resistor.
____________________________________________________________________
____________________________________________________________________
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Name : ____________________________________________________ Group :____________
Course :__________________________________________ Date: _________________________
Lab Task 1 : Parallel Resistor
Using a parallel circuit you are able to divide currents in a circuit. This is used in electronics,
but also in electrical engineering. Refer to the schematic diagram below. Make an electronic
circuit arrangement based on given schematic above on breadboard.
𝐼𝑇
(𝑉𝑇 ) 5 V
𝐼1
(𝑅1 ) 1 kΩ
LED 1
1
1
a). Calculate total resistor. [𝑅𝑇 = 𝑅 + 𝑅 ].
1
2
b). Using Multimeter, measure the current 𝐼1 , 𝐼2 and 𝐼𝑇 .
c). Verify that 𝐼1 + 𝐼2 = 𝐼𝑇 .
d). Using multimeter, measure 𝑉𝑅1and 𝑉𝑅2 .
𝐼2
100 Ω
(𝑅2 )
LED 2
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e). Using multimeter, measure 𝑉𝑅1 + 𝑉𝐿𝐸𝐷1 and 𝑉𝑅2 + 𝑉𝐿𝐸𝐷2 .
f). Prove that 𝑉𝑅1 + 𝑉𝐿𝐸𝐷1= 𝑉𝑅2 + 𝑉𝐿𝐸𝐷2 = 𝑉𝑇 .
g). This circuit is also known as current divider. Do you agree? Write down your
argument.
________________________________________________________________
________________________________________________________________
________________________________________________________________
________________________________________________________________
h). Based on the value of current and voltage obtained from this task, and the brightness of
LED, write your conclusion on this circuit.
________________________________________________________________
________________________________________________________________
________________________________________________________________
________________________________________________________________
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Lab Module
Name : ____________________________________________________ Group :____________
Course :__________________________________________ Date: _________________________
Lab Task 1 : Serial Resistor
A series circuit of resistors generates certain voltages. In the last experiment, you halved the voltage
of the battery. With other resistors you generate other voltages. Make an electronic circuit
arrangement based on given schematic above on breadboard.
(𝐼𝑅1 )
𝐼1
(𝑅1 )
5V
100 Ω
(𝐼𝑅2 )
(𝑉𝑇 )
(𝑅2 )
1 kΩ
LED
a). Calculate total resistor. [𝑅1 + 𝑅2 = 𝑅𝑇 ]
b). Using multimeter, measure the voltage for 𝑉𝑅1and 𝑉𝑅2.
c). Verify that 𝑉𝑇 = 𝑉𝑅1 + 𝑉𝑅2 + 𝑉𝐿𝐸𝐷 .
d). Using multimeter, determine the current 𝐼1.
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e). Using the equation𝑉 = 𝐼𝑅, determine the current 𝐼𝑅1 and𝐼𝑅2 .
f). This circuit is also known as voltage divider. Do you agree? Write down your
argument.
________________________________________________________________
________________________________________________________________
________________________________________________________________
________________________________________________________________
g). Based on the value of current and voltage obtained from this task, write your
conclusion on this circuit.
________________________________________________________________
________________________________________________________________
________________________________________________________________
________________________________________________________________
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Name : ____________________________________________________ Group :____________
Course :__________________________________________ Date: _________________________
Lab Task 2 : Potentiometer
A potentiometer is a manually adjustable electrical resistor that uses three terminals. It is a
simple electro-mechanical transducer. It converts rotary or linear motion from the operator
into a change of resistance, and this change is used to control the levels of output.
a) Potentiometer comes with three terminals as shown below.
C
B
A
Using multimeter, determine the minimum and maximum resistance for potentiometer.
i. Connect your multimeter between A and B, measure its minimum and maximum
resistance.
𝑀𝑖𝑛𝑅𝐴𝐵 = _________ Ω
𝑀𝑎𝑥𝑅𝐴𝐵 = ________ Ω
ii. Connect your multimeter between A and C, measure its minimum and maximum value of
resistance.
𝑀𝑖𝑛𝑅𝐴𝐶 =
Ω
𝑀𝑎𝑥𝑅𝐴𝐶 =
Ω
iii. Connect your multimeter between B and C, measure its minimum and maximum value of
resistance.
𝑀𝑖𝑛𝑅𝐵𝐶 =
Ω
𝑀𝑎𝑥𝑅𝐵𝐶 =
Ω
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iv. Write a conclusion regarding the resistance values obtained above.
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
b) Make an electronic circuit arrangement based on given schematic diagram below on
breadboard.
I
220 Ω
A
9V
B
LED
Set the potentiometer at the minimum value of resistance. Your minimum value is ____ Ω.
i. Using multimeter, measure the voltage between point A and B.
ii. Write down your observation for LED (in terms of brightness).
iii. Measure the current, I. ____ A
Set the potentiometer at the maximum value of resistance. Your maximum value is ____ Ω.
iv. Using multimeter, measure the voltage between point A and B.
v. Write down your observation for LED (in terms of brightness).
v.
Measure the current, I. ____A.
Engineering Skills ECT112 / PCT 112
c). Describe any potential practical applications of a potentiometer.
________________________________________________________________
________________________________________________________________
________________________________________________________________
________________________________________________________________
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Name : ____________________________________________________ Group :____________
Course :__________________________________________ Date: _________________________
Lab Task 2 : Capacitor Serial and Parallel
A capacitor is a tool consisting of two conductive plates, each of which hosts an opposite
charge. These plates are separated by a dielectric or other form of insulator, which helps them
maintain an electric charge.
i). Capacitor in series. Capacitor is used to store charges.
R1
LED 1
470𝛺
S1
S2
100µF +
C1
9V
100µF +
C2
R2
470𝛺
LED 2
a) Develop the schematic to breadboard. Set the power supply voltage at 9V.
b) First, close switch S1 and open switch S2, write your observation for both LED.
__________________________________________________________________
__________________________________________________________________
c) Next, open switch S1 and close switch S2, write your observation for both LED.
__________________________________________________________________
__________________________________________________________________
d) Based from the experiment above, write your conclusions regarding capacitor.
__________________________________________________________________
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e) Using the formula𝐶𝑇 =
1
𝐶1
+
1
,
𝐶2
calculate the total value of capacitor.
f) How to make LED lights longer?
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Engineering Skills ECT112 / PCT 112
Lab Module
ii). Capacitor in parallel. Capacitor is used to store charges.
LED 1
R1
470Ω
S1
S2
R2
100µF
9V
+
C1
+
C2
470Ω
100µF
LED 2
a) Develop the schematic to breadboard. Set the power supply voltage at 9V.
b) First, close switch S1 and open switch S2, write your observation for both LED.
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c) Next, open switch S1 and close switch S2, write your observation for both LED.
d) __________________________________________________________________
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e) Using the formula𝐶𝑇 = 𝐶1 + 𝐶2 calculate the total value of capacitor.
f) How to make LED lights longer?
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g) Based from both experiment about capacitor, which types of capacitor combination makes the
LED lights longer?
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h) Give your suggestions to make LED turn ON for a long time.
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Engineering Skills ECT112 / PCT 112
Lab Module
Name : ____________________________________________________ Group :____________
Course :__________________________________________ Date: _________________________
Lab Task 2 : LDR and Transistor
Light dependent resistor is a small, round semiconductor. Light dependent resistors are used
to re-charge a light during different changes in the light, or they are made to turn a light on
during certain changes in lights.
470kΩ
100 kΩ
LED
DC
6V
NPN
LDR
a). Develop a circuit on bread board base on the schematic diagram above. Set the power
supply at 6V.
b). After completing the development of circuit on breadboard. Do not turn ON the power
supply. Measure the resistance of LDR.
Cover the LDR =
Ω
Don’t cover the LDR =
Ω
c). Base from the resistance that you measured in (b). Write a brief conclusion about LDR.
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d). Turn ON the power supply. Using multimeter, measure the voltage of LDR.
Cover the LDR =
V
Don’t cover the LDR =
V
Engineering Skills ECT112 / PCT 112
Lab Module
Measure the resistance of LDR.
Cover the LDR =
Ω
Don’t cover the LDR =
Ω
e). Give an example the application of LDR.
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f).What is the function of Transistor.
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g). Give an explanation on how this circuit works.
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Engineering Skills ECT112 / PCT 112
Lab Module
Name : ____________________________________________________ Group :____________
Course :__________________________________________ Date: _________________________
Lab Task 2 : IC Timer
Timer 555.
+9V
16kΩ
47kΩ
7
6
8
4
Timer
555
470Ω
5
2
Trigger
3
0.01µF
100µF
0V
a). Based from you understanding, what is the timer?
b). Write the name for each pin below.
………………
……
………………
……
………………
……
………………
1
8
2
7
3
6
4
5
……
………………
……
………………
……
………………
……
………………
……
c). Where can you find the application of timer? List three.
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d). Suggest, how to make the delay time much longer?
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Engineering Skills ECT112 / PCT 112
e). Give an explanation on how this circuit works.
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Lab Module