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Page 1 of 46
EX. NO: 0 1
DATE:
FAMILIARIZATION/IDENTIFICATION OF ELECTRONIC
COMPONENTS WITH SPECIFICATION
AIM:
To Familiarization/Identification of electronic components with specification -Active, Passive, Electrical, Electronic, Electro-mechanical, Wires, Cables, Connectors,
Fuses, Switches, Relays, Crystals, Displays, Fasteners, Heat sink
COMPONENTS AND EQUIPMENTS REQUIRED:
Resistors, Capacitors, Inductors, diode, power supply, transistors, transformer, relay,
switches, ICs, crystals, 7-segment display, heat sink
THEORY:
ACTIVE components increase the power of a signal and must be supplied with the signal
and a source of power. Examples are bipolar transistors, field effect transistors etc. The
signal is fed into one connection of the active device and the amplified version taken
from another connection. In a transistor, the signal can be applied to the base
connection and the amplified version taken from the collector. Some of the active
components are diodes, transistors, integrated circuits, optoelectronic components
PASSIVE components do not increase the power of a signal. They often cause power to
be lost. Some can increase the voltage at the expense of current, so overall there is a
loss of power. Resistors, capacitors, inductors and diodes, sensors, detectors, antennas
are examples of passive components.
1. Resistor:
Resistors are designed to allow for a measured resistance that can affect either
voltage or current as calculated by using Ohm’s law. As an example, a resistor could
be used in an electrical test meter to limit the current flow. Fixed resistors can be
made from nickel wire wound on a ceramic tube and then covered with porcelain.
Smaller fixed resistors are made from mixtures of powdered carbon and insulating
materials molded into a round tubular shape. Variable resistors have a tightly
wound coil of resistance wire made into a circular shape. The resistance value is
changed by turning an adjustment that moves the point of contact along the circular
coil. Some variable resistors can be controlled by a small knob, while others are
adjusted with a screwdriver. Adjustable resistors are often used for electronic
circuits.
Resistor colour bands:
Markings on resistors can vary. Larger resistors have printed resistance values,
while smaller resistors have color-coded bands. To determine the resistance of a
color-coded resistor, start from the end opposite the silver or gold band. Use the
color code chart from figure (fig -1.1) to determine the resistance values. The first
two bands identify the first and second digits of the resistance value, and the third
band indicates the number of zeroes. However, if the third band is silver, this will
Dept. of ECE, TEC, Vellarakkad
EW/ LM 01
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indicate a 0.01 multiplier. If the third band is gold, this will indicate a 0.1 multiplier.
The fourth band indicates tolerance. Silver indicates a +/- 10 percent tolerance, and
gold indicates a +/- 5 percent tolerance. If there is no fourth band, the resistor
tolerance is +/- 20 percent.
Variable resistor with 2 contacts (a rheostat) is usually used to control current.
Examples: adjusting lamp brightness, adjusting motor speed, and adjusting the rate of
flow of charge in to a capacitor in a timing circuit. Variable resistor with 3 contacts (a
potentiometer) is usually used to control voltage. It can be used like this as a transducer
converting position (angle of the control spindle) to an electrical signal. Variable resistor
(a preset) is operated with a small screwdriver or similar tool. It is designed to be set
when the circuit is made and then left without further adjustment. Presets are cheaper
than normal variable resistors so they are often used in projects to reduce the cost.
Images:
Fig1.1. Resistor colour bands
Symbols:
Resistor
Variable Resistor (Rheostat)
Variable Resistor (Potentiometer)
Dept. of ECE, TEC, Vellarakkad
EW/ LM 01
Page 3 of 46
Variable Resistor (Preset)
2. Capacitor
A capacitor will store energy when an electric charge is forced onto its plates
from a power source. A capacitor will still retain this charge even after
disconnection from the power source. Compared to a storage battery, the total
amount of energy stored by a capacitor is relatively small. Also, the discharge rate of
a capacitor is rapid, so the release of the stored energy only occurs during a short
time interval.
Not all capacitors are made of the same materials. There are paper and film,
electrolytic, ceramic, and mica capacitors. Disc ceramic capacitors are commonly
found on electronic circuit boards and are typically 0.1 microfarads (mfd) or less.
Mica capacitors are limited to even lower values than this. For larger-capacitance
requirements, paper and film capacitors are used. They are constructed using a
rolled-foil technique. Once rolled, the capacitor may be dipped into a plastic
insulating material. Capacitors of this type used for electronic circuits are rated at
generally less than 1 mfd. However, they can also be designed for industrial
applications to meet the requirements of several hundred microfarads. In this case,
they would be housed in a metal container filled with special insulation oil.
A capacitor stores electric charge. A capacitor is used with a resistor in a timing
circuit. It can also be used as a filter, to block DC signals but pass AC signals. A variable
capacitor is used in a radio tuner. Variable capacitor (a trimmer) is operated with a small
screwdriver or similar tool. It is designed to be set when the circuit is made and then left
without further adjustment.
Symbols:
capacitor
Capacitor,polarised
Variable Capacitor
Dept. of ECE, TEC, Vellarakkad
EW/ LM 01
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Trimmer capacitor
3. Inductor
A coil of wire which creates a magnetic field when current passes through it. It have
an iron core inside the coil. It can be used as a transducer converting electrical energy to
mechanical energy by pulling on something.
Symbol:
Inductor:
4. Diodes
A diode is a semiconductor that acts similar to a check valve, allowing for oneway flow through an electrical circuit. A diode has an anode and a cathode. If the
anode is connected to the positive terminal, then the diode is forward biased and
current will flow. If the anode is connected to the negative terminal, then the diode is
reverse biased and no current will flow. Diodes can vary from the size of a pinhead
to much larger sizes for ratings of 500 amperes or more.
A light emitting diode(LED) is a transducer which converts electrical energy to light. A
special diode called zener diode, which is used to maintain a fixed voltage across its
terminals. Finally a photo diode is a light-sensitive diode.
Symbols:
Diode:
Light Emitting Diode(LED)
Zener diode
Photo diode
Dept. of ECE, TEC, Vellarakkad
EW/ LM 01
Page 5 of 46
5. Transistors
Transistors were one of the first most popular solid-state devices used and
became well known for the mass production of transistor radios. They can be used
as a switch or to amplify an electrical signal. As an example, in a HVACR system,
these can be used to amplify a signal of low-voltage/ low-current power to a highervoltage/ higher-current power to operate a relay. A transistor amplifies current. It
can be used with other components to make an amplifier or switching circuit. A
phototransistor is a light-sensitive transistor.
Symbol:
NPN transistor:
PNP transistor:
Phototransistor
6. Transformer
In transformer two coils of wire linked by an iron core. Transformers are used to step
up (increase) and step down (decrease) AC voltages. Energy is transferred between the
coils by the magnetic field in the core. There is no electrical connection between the
coils.
Transformer symbol:
Transformers are constructed using the induction characteristics of AC power. When
current flows through a coil, a magnetic field is produced. When a second coil is
placed in the field of the current-carrying coil (primary), electric current can be
transferred to the second coil (secondary). The process is made more efficient by
wrapping the coils around a common metal core. The voltage transferred is directly
in proportion to the ratio of the number of turns on the primary coil to the number
of turns on the secondary coil.
Dept. of ECE, TEC, Vellarakkad
EW/ LM 01
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More than one secondary coil can be used if additional voltages or circuits are
required. Likewise, some transformers are made with more than one primary. These
multiple windings can then be connected in series or parallel to change the voltage
or current capability of the transformer. Center-tapped transformers allow for a
small change in the windings voltage rating by changing taps. Variable
autotransformers also allow for changing the voltage output. Three-phase
transformers are generally used for three phase power. However, a single-phase
transformer for each leg (three single-phase transformers) would produce the same
results.
7. Relays
An automatic switch requires some method for opening and closing. This is often
accomplished through the use of a relay. A relay is an electrically operated switch
that uses an electromagnet to open or close a set of electrical contacts. Normally
only a small amount of current is required to energize the electromagnet. Relays can
be designed for normally open switches or normally closed switches. The normal
position of the switch is always the position of the switch when the relay coil is deenergized; normally closed set of contacts with the relay coil is de-energized. A
spring is used to hold the contacts together. When the coil is energized (supplied
with current), a magnetic field is set up that attracts the lower contact toward the
coil. This will separate the two contacts and open the circuit. As long as the current
flows through the coil, the relay is energized, and the switch will remain open. With
a normally open set of contacts, the spring holds the contacts open. When the coil is
energized, the magnetic field pulls the contacts together.
Image of Relay:
An electrically operated switch, for example a 9V battery circuit connected to the
coil can switch a 230V AC mains circuit. NO = Normally Open, COM = Common, NC =
Normally Closed.
Symbol:
Relay:
Dept. of ECE, TEC, Vellarakkad
EW/ LM 01
Page 7 of 46
8. Switches
Switches can come in all shapes and sizes
SPST
A Single Pole Single Throw toggle switch connects or disconnects one
terminal either to or from another. It is the simplest switch.
SPST Schematic Symbol and Image:
SPDT
A Single Pole Double Throw toggle switch connects a common terminal to
one or the other of two terminals. It is always connected to one or the other. The two
outside terminals are never connected by the switch.
SPDT Schematic Symbol and Image:
DPDT
A Double Pole Double Throw toggle switch acts exactly like two separate
SPDT switches connected to the same switch bat. It has two separate common
terminals and each of those is connected to one or the other of the other two
terminals on the same side of the switch. The dotted line in the picture is to illustrate
that the switch is actually two SPDT switches in one package with one switch bat.
SPDT Schematic Symbol:
Dept. of ECE, TEC, Vellarakkad
EW/ LM 01
Page 8 of 46
9. Fuses
A fuse is a special electrical conductor that is placed in series with a load and
melts when excessive current flows through it, opening the circuit. Fuses are
available in different types and sizes so that they can be selected to match the
requirements of specific loads. If they are too small, they melt before they should. If
they are too large, they do not offer the proper protection. Cartridge fuses are the
most common one. Fuses are grouped by physical size. Up to 30 amps is one physical
size; over 30 amps and up to 60 amps is a larger size. Fuses are also rated for
voltage. Fuses designed for 600 volts are much larger than fuses designed for 250
volts. A sample fuse and two commonly used fuse symbols are shown in figure below,
10. Wires, Cables and Connectors
Wires are used to pass current very easily from one part of a circuit to another.
Wires are joined by a 'blob' should be drawn where wires are connected (joined), but it
is sometimes omitted. Wires connected at 'crossroads' should be staggered slightly to
form two T junctions. In complex diagrams it is often necessary to draw wires crossing
even though they are not connected. The simple crossing on the left is correct but may
be misread as a join so a bridge symbol is used instead of cross.
The two most common types of single conductor wires are THW and THWN/THHN,
which are protected by metal or plastic sheathing. The wires themselves can be either
solid or stranded. Solid-core wire produces the best connections, but its stiffness makes it
more difficult than stranded.
Symbol of Wire:
Symbol for Wire ‘joins’ and ‘no join’:
Dept. of ECE, TEC, Vellarakkad
EW/ LM 01
Page 9 of 46
An electrical connector is an electro-mechanical device for joining electrical
circuits as an interface using a mechanical assembly. Connectors consist of plugs
(male-ended) and jacks (female-ended). The connection may be temporary, as for
portable equipment, require a tool for assembly and removal, or serve as a
permanent electrical joint between two wires or devices. An adapter can be used to
effectively bring together dissimilar connectors. There are hundreds of types of
electrical connectors. Connectors may join two lengths of flexible copper wire or
cable, or connect a wire or cable to an electrical terminal. That is an electrical
connector can also be known as a physical interface.
Connector Symbol:
An electrical cable comprises two or more wires running side by side and
bonded, twisted, or braided together to form a single assembly, the ends of which
can be connected to two devices, enabling the transfer of electrical signals from one
device to the other. Cables are used for a wide range of purposes, and each must be
tailored for that purpose. Cables are used extensively in electronic devices for power
and signal circuits.
Electrical cable cross section:
11. Piezoelectric crystals and seven-segment display (SSD)
A piezoelectric substance is one that produces an electric charge when a
mechanical stress is applied (the substance is squeezed or stretched). Conversely, a
mechanical deformation (the substance shrinks or expands) is produced when an
electric field is applied. There are many materials, both natural and man-made, that
exhibit a range of piezoelectric effects. Some naturally piezoelectric occurring
materials include Berlinite (structurally identical to quartz), cane sugar, quartz,
Rochelle salt etc.
A seven-segment display (SSD), or seven-segment indicator, is a form of
electronic display for displaying decimal numerals that is an alternative to the more
complex dot-matrix displays. Seven-segment displays are widely used in digital
clocks, electronic meters, basic calculators, and other electronic devices that display
numerical information.
Dept. of ECE, TEC, Vellarakkad
EW/ LM 01
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12. Heat sink
In electronic systems, a heat sink is a passive heat exchanger that cools a device
by dissipating heat into the surrounding medium. In computers, heat sinks are used
to cool central processing units or graphics processors. Heat sinks are used with
high-power semiconductor devices such as power transistor and optoelectronics
such as lasers and light emitting diodes (LEDs), where the heat dissipation ability of
the basic device is insufficient to moderate its temperature.
RESULT:
Familiarized each electronic component with specification.
Dept. of ECE, TEC, Vellarakkad
EW/ LM 01
Page 11 of 46
EX. NO: 02
DATE:
TESTING OF ELECTRONIC COMPONENTS
AIM:
Test the electronic components, resistor, capacitor, diode, transistor, UJT and JFET
using multimeter.
COMPONENTS AND EQUIPMENTS REUIRED:
Resistor, capacitors, diode, transistor, UJT and JFET.
THEORY
MULTIMETERS:
There are two types: Digital and Analogue. A digital multimeter has a set of
digits on the display and an Analogue multimeter has a scale with a pointer (or
needle).
Analogue and digital multimeters have either a rotary selector switch or push
buttons to select the appropriate function and range. Some Digital Multimeter
(DMMs) are auto ranging; they automatically select the correct range of voltage,
resistance, or current when doing a test, however it requires to select the function.
For voltage measurment, select the AC range (10v, 50v, 250v, or 1000v) or DC range
(0.5v, 2.5v, 10v, 50v, 250v, or 1000v), for measuring resistance, select the Ohms
range (x1, x10, x100, x1k, x10k), and for measuring current, select the appropriate
current range DCmA 0.5mA, 50mA, 500mA.
The common(negative) lead always fits into the “COM” socket. The red lead
fits in to the red socket for voltage and resistance and place the red lead(red banana
plug) in to “A” for high current “Amp” or mA, uA for low current.
PROCEDUURE
Voltage/current measurement:
1. Select the highest range or use the auto-ranging feature, by selecting "V."/
“A”.
2. Measure the voltage at different points in a circuit by connecting the black
probe to chassis/ground and the red lead called the "measuring lead" or
"measuring probe" at any point in a circuit.Note down the AC or DC voltage
value on display.
3. Remove one end of a component and measure current with the two probes in
the "opening". Current is always measured in series. Note down the AC or DC
current value on display.
Resistor Testing:
1. Turn power to circuit OFF. If a circuit includes a capacitor, discharge the
capacitor before taking any resistance reading.
Dept. of ECE, TEC, Vellarakkad
EW/ LM 01
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2. Plug the probes into the correct test sockets-to test for resistance are one
labeled "COM" (for common) and one labeled with the Greek letter omega,
which is the abbreviation for "ohm."
3. Turn on the multimeter, select the maximum testing range for the
multimeter, but if reading appears near 0, dial the range down.
4. Put the two probes across the resistor/item whose resistance to be measured
and read the number on display.
Capacitor Testing:
1. Use digital multimeter (DMM) to ensure all power to the circuit is OFF. If the
capacitor is used in an ac circuit, set the multimeter to measure ac voltage. If
is used in a dc circuit, set the DMM to measure dc voltage.
2. Visually inspect the capacitor. If leaks, cracks, bulges or other signs of
deterioration are evident, replace the capacitor.
3. Turn the dial to the Capacitance Measurement mode.
4. For a correct measurement, the capacitor will need to be removed from the
circuit. Discharge the capacitor.
5. Connect the test leads to the capacitor terminals. Keep test leads connected
for a few seconds to allow the multimeter to automatically select the proper
range.
6. Read the measurement displayed. If the capacitance value is within the
measurement range, the multimeter will display the capacitor’s value. It will
display OL if a) the capacitance value is higher than the measurement range
or b) the capacitor is faulty.
Diode Testing:
1. Make sure no voltage exists across the diode. Voltage may be present in the
circuit due to charged capacitors. If so, the capacitors need to be discharged.
Set the multimeter to measure ac or dc voltage as required.
2. Turn the dial (rotary switch) to Diode Test mode (
). It may share a space
on the dial with another function.
3. Connect the test leads to the diode. Record the measurement displayed.
4. Reverse the test leads. Record the measurement displayed.
Diode test analysis:
A good forward-based diode displays a voltage drop ranging from 0.5 to 0.8
volts for the most commonly used silicon diodes. Some germanium diodes
have a voltage drop ranging from 0.2 to 0.3 V.
2. The multimeter displays OL when a good diode is reverse-biased. The OL
reading indicates the diode is functioning as an open switch.
3. A bad (opened) diode does not allow current to flow in either direction. A
multimeter will display OL in both directions when the diode is opened.
4. A shorted diode has the same voltage drop reading (approximately 0.4 V) in
both directions.
1.
Dept. of ECE, TEC, Vellarakkad
EW/ LM 01
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A multimeter set to the Resistance mode (Ω) can be used as an additional diode test
if a multimeter does not include the Diode Test mode.
The resistance mode procedure is conducted as follows:
1. Make certain a) all power to the circuit is OFF and b) no voltage exists at the
diode. Voltage may be present in the circuit due to charged capacitors. If so,
the capacitors need to be discharged. Set the multimeter to measure ac or dc
voltage as required.
2. Turn the dial to Resistance mode (Ω). It may share a space on the dial with
another function.
3. Connect the test leads to the diode after it has been removed from the circuit.
Record the measurement displayed.
4. Reverse the test leads. Record the measurement displayed.
5. The forward-biased resistance of a good diode should range from 1000 Ω to
10 MΩ. The reverse-biased resistance of a good diode displays OL on a
multimeter.
Transistor Testing:
1. Remove the transistor from the circuit for accurate test results.
2. Base to Emitter: Hook the positive lead from the multimeter to the to
the BASE (B) of the transistor. Hook the negative meter lead to the EMITTER
(E) of the transistor. For an good NPN transistor, the meter should show
a voltage drop between 0.45V and 0.9V. If you are testing PNP transistor, you
should see “OL” (Over Limit).
3. Base to Collector: Keep the postitive lead on the BASE (B) and place the
negative lead to the COLLECTOR (C).For an good NPN transistor, the meter
should show a voltage drop between 0.45V and 0.9V. If you are testing PNP
transistor, you should see “OL” (Over Limit).
4. Emitter to Base: Hook the positive lead from the multimeter to the to
the EMITTER (E) of the transistor. Hook the negative meter lead to the BASE
(B) of the transistor.For an good NPN transistor, you should see “OL” (Over
Limit).If you are testing PNP transistor, the meter should show a voltage drop
between 0.45V and 0.9V.
Dept. of ECE, TEC, Vellarakkad
EW/ LM 01
Page 14 of 46
5. Collector to Base: Hook the positive lead from the multimeter to the to
the COLLECTOR (C) of the transistor. Hook the negative meter lead to the
BASE (B) of the transistor.For an good NPN transistor, you should see “OL”
(Over Limit).If you are testing PNP transistor, the meter should show a
voltage drop between 0.45V and 0.9V.
6. Collector to Emitter:Hook the postitive meter lead to the COLLECTOR
(C) and the negative meter lead to the EMITTER (E) – A good NPN or PNP
transistor will read”OL”/Over Limit on the meter. Swap the leads (Positive to
Emitter and Negative to Collector) – Once again, a good NPN or PNP
transistor should read “OL”.
Testing of JFET Transistor:
Testing a JFET with a multimeter is by, seeing as how it has only one PN
junction to test: either measured between gate and source, or between gate and
drain.
Dept. of ECE, TEC, Vellarakkad
EW/ LM 01
Page 15 of 46
Testing UJT transistor:
STEP-1
1. Select DMM to Diode Mode
2. Connect DMM posetive test lead to Emitter of UJT 2N2646.
3. DMM Negative test lead to Base-1 = Display reading shows .650v
4. DMM Negative test lead to base-2 = Display reading shows .735v
STEP-2
1. Connect DMM Negative test lead to Emitter.
2. DMM posetive test lead to Base-1 OL DMM READING SHOWS open
3. DMM posetive test lead to Base-2 OL open
4. DMM Negative test lead to Base-1 0.874v
RESULT
Tested the electronic components, resistor, capacitor, diode, transistor, UJT and JFET
using multimeter.
Dept. of ECE, TEC, Vellarakkad
EW/ LM 01
Page 16 of 46
EX. NO: 03
DATE:
FAMILIARIZATION/APPLICATION OF TESTING INSTRUMENTS
AND COMMONLY USED TOOLS
AIM:
Familiarize testing instruments and commonly used tools.
COMPONENTS AND EQUIPMENTS REUIRED:
Multimeter, Function generator, Power supply, CRO ,Soldering iron, De
soldering pump, Pliers, Cutters, Wire strippers, Screw drivers, Tweezers, Crimping
tool,
THEORY
MULTIMETERS:
There are two types: Digital and Analogue. A digital multimeter has a set of
digits on the display and an Analogue multimeter has a scale with a pointer (or
needle).
Analogue and digital multimeters have either a rotary selector switch or push
buttons to select the appropriate function and range. Some Digital Multimeter
(DMMs) are auto ranging; they automatically select the correct range of voltage,
resistance, or current when doing a test, however it requires to select the function.
For voltage measurment, select the AC range (10v, 50v, 250v, or 1000v) or DC range
(0.5v, 2.5v, 10v, 50v, 250v, or 1000v), for measuring resistance, select the Ohms
range (x1, x10, x100, x1k, x10k), and for measuring current, select the appropriate
current range DCmA 0.5mA, 50mA, 500mA.
The common(negative) lead always fits into the “COM” socket. The red lead
fits in to the red socket for voltage and resistance and place the red lead(red banana
plug) in to “A” for high current “Amp” or mA, uA for low current.
CATHODE RAY OSCILLOSCOPE:
The cathode-ray oscilloscope (CRO) is a common laboratory instrument that
provides accurate time and amplitude measurements of voltage signals over a wide
range of frequencies. Its reliability, stability, and ease of operation make it suitable
as a general purpose laboratory instrument. The heart of the CRO is a cathode-ray
tube shown schematically in figure
Dept. of ECE, TEC, Vellarakkad
EW/ LM 01
Page 17 of 46
Fig1: cathode ray tube: (a) schematic,(b) detail of the deflection plates
The cathode ray is a beam of electrons which are emitted by the heated
cathode (negative electrode) and accelerated toward the fluorescent screen. The
assembly of the cathode, intensity grid, focus grid, and accelerating anode (positive
electrode) is called an electron gun. Its purpose is to generate the electron beam and
control its intensity and focus. Between the electron gun and the fluorescent screen
is two pair of metal plates - one oriented to provide horizontal deflection of the
beam and one pair oriented to give vertical deflection to the beam. These plates are
thus referred to as the horizontal and vertical deflection plates. The combination of
these two deflections allows the beam to reach any portion of the fluorescent screen.
Wherever the electron beam hits the screen, the phosphor is excited and light is
emitted from that point. This conversion of electron energy into light allows us to
write with points or lines of light on an otherwise darkened screen.
The voltage output of such a generator is that of a sawtooth wave as shown in
Fig. 2. Application of one cycle of this voltage difference, which increases linearly
with time, to the horizontal plates causes the beam to be deflected linearly with time
across the tube face. When the voltage suddenly falls to zero, as at points (a) (b) (c),
etc.. the end of each sweep – the beam flies back to its initial position. The horizontal
deflection of the beam is repeated periodically, the frequency of this periodicity is
adjustable by external controls.
Fig2: Voltage difference V between horizontal plates as a function of time t
To obtain steady traces on the tube face, an internal number of cycles of the
unknown signal that is applied to the vertical plates must be associated with each
Dept. of ECE, TEC, Vellarakkad
EW/ LM 01
Page 18 of 46
cycle of the sweep generator. Thus, with such a matching of synchronization of the
two deflections, the pattern on the tube face repeats itself and hence appears to
remain stationary. The persistence of vision in the human eye and of the glow of the
fluorescent screen aids in producing a stationary pattern. In addition, the electron
beam is cut off (blanked) during flyback so that the retrace sweep is not observed.
Fig 3:circuit diagram of CRO
An oscilloscope is a measuring device used commonly for measurement of
voltage, current, frequency, phase difference and time intervals. The heart of the
oscilloscope is the cathode ray tube, which generates the electron beam, accelerates
the beam to high velocity, deflects the beam to create the image, and contains the
phosphor screen where the electron beam eventually becomes visible. To
accomplish these tasks, various electrical signals and voltages are required. The
power supply block provides the voltages required by the cathode ray tube to
generate and accelerate the electron beam, as well as to supply the required
operating voltages for the other circuits of the oscilloscope. Relatively high voltages
are required by the cathode tubes, on the order of a few thousand volts, for
acceleration, as well as a low voltage for the heater of the electron gun, which emits
the electrons. Supply voltages for the other circuits are various values usually not
more than few hundred volts.
The oscilloscope has a time base, which generates the correct voltage to
supply the cathode ray tube to deflect this part at a constant time dependent rate.
The signal to be view is fed to you vertical amplifier, which increases the potential of
the input signal to a level that will provide a usable deflection of the electron beam.
To synchronize the horizontal deflection the vertical input, such that the horizontal
deflection starts at the same point of the input vertical signal each time it sweeps, a
synchronizing or triggering circuit is used. This circuit is the link between the
vertical input and the horizontal time base.
Dept. of ECE, TEC, Vellarakkad
EW/ LM 01
Page 19 of 46
FUNCTION GENERATOR:
A function generator is a device that can produce various patterns of voltage at a
variety of frequencies and amplitudes.
 It is used to test the response of circuits to common input signals. The
electrical leads from the device are attached to the ground and signal input
terminals of the device under test.
Features and controls
 Most function generators allow the user to choose the shape of the output
from a small number of options.
 Square wave - The signal goes directly from high to low voltage.
 Sine wave - The signal curves like a sinusoid from high to low voltage.
 Triangle wave - The signal goes from high to low voltage at a fixed rate.
 The amplitude control on a function generator varies the voltage difference
between the high and low voltage of the output signal.
 The direct current (DC) offset control on a function generator varies the
average voltage of a signal relative to the ground.
 The frequency control of a function generator controls the rate at which
output signal oscillates. On some function generators, the frequency control
is a combination of different controls.
 One set of controls chooses the broad frequency range (order of magnitude)
and the other selects the precise frequency. This allows the function
generator to handle the enormous variation in frequency scale needed for
signals.
POWER SUPPLY:
There are many types of power supply. Most are designed to convert high
voltage AC mains electricity to a suitable low voltage supply for electronic circuits
and other devices. A power supply can by broken down into a series of blocks, each
of which performs a particular function.
For example a 5V regulated supply:
Each of the blocks is described in more detail below:



Transformer - steps down high voltage AC mains to low voltage AC.
Rectifier - converts AC to DC, but the DC output is varying.
Smoothing - smoothes the DC from varying greatly to a small ripple.
Dept. of ECE, TEC, Vellarakkad
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
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Regulator - eliminates ripple by setting DC output to a fixed voltage.
WIRE CUTTER:
Diagonal pliers (or wire cutters or diagonal cutting pliers) are pliers intended
for the cutting of wire (they are generally not used to grab or turn anything). They
are sometimes called side cutting pliers or side cutters. The pliers are made of
tempered steel and inductive heatingand quenching are often used to selectively
harden the Diags or Dikes.The handles of diagonal cutting pliers are commonly
insulated with a dip-type or shrink fitelectrically-insulating material for comfort and
some protection against electric shock.
Diagonal pliers are useful for cutting copper, brass, iron, aluminium and steel
wire. Lower quality versions are generally not suitable for cutting tempered steel,
such as piano wire, as the jaws are not hard enough. For electronics work, special
diagonal cutters that are ground flush to the apex of the cutting edge on one side of
the jaws are often used. These flush-cutting pliers allow wires to be trimmed flush or
nearly flush to a solder joint, avoiding the sharp tip left by symmetrical diagonal
cutters. It is common for this type of diagonal cutter to be referred to by another
name, such as "flush cutter" to distinguish it from symmetrical cutters.
WIRE STRIPPER:
A wire stripper is a small, hand-held device used to strip the insulation from
electric wires. A simple manual wire stripper is a pair of opposing blades much like
scissors or wire cutters. The addition of a center notch makes it easier to cut the
insulation without cutting the wire. This type of wire stripper is used by rotating it
around the insulation while applying pressure in order to make a cut around the
insulation. Since the insulation is not bonded to the wire, it then pulls easily off the
end. This is the most versatile type of wire stripper. Another type of manual wire
stripper is very similar to the simple design previously mentioned, except this type
has several notches of varying size. This allows the user to match the notch size to
the wire size, thereby eliminating the need for twisting. Once the device is clamped
on, the remainder of the wire can simply be pulled out, leaving the insulation behind.
PLIERS:
Pliers are a hand tool used to hold objects firmly, for cutting, bending, or
physical compression. Generally, pliers consist of a pair of metal first-class levers
joined at a fulcrum positioned closer to one end of the levers, creating short jaws on
one side of the fulcrum, and longer handles on the other side. This arrangement
creates a mechanical advantage, allowing the force of thehand's grip to be amplified
and focused on an object with precision. The jaws can also be used to manipulate
objects too small or unwieldy to be manipulated with the fingers.
There are many kinds of pliers made for various general and specific
purposes. The basic design of pliers has changed little since their origins, with the
pair of handles, the pivot (often formed by a rivet), and the head section with the
Dept. of ECE, TEC, Vellarakkad
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gripping jaws or cutting edges forming the three elements. In distinction to a pair of
scissors or shears, the plier's jaws always meet each other at one pivot angle.
The materials used to make pliers consist mainly of steel alloys with additives
such as vanadium or chromium, to improve strength and prevent corrosion. Often
pliers have insulated grips to ensure better handling and prevent electrical
conductivity. In some lines of fine work (such as jewellery or musical instrument
repair), some specialized pliers feature a layer of comparatively soft metal (such as
brass) over the two plates of the head of the pliers to reduce pressure placed on
some fine tools or materials. Making entire pliers out of softer metals would be
impractical, reducing the force required to bend or break them.
CRIMPING:
Crimping is joining two pieces of metal or other malleable material by
deforming one or both of them to hold the other. The bend or deformity is called the
crimp. Crimping is most extensively used in metalworking. Crimping is commonly
used to join bullets to their cartridge cases, and for rapid but lasting electrical
connectors. Because it can be a cold working technique, crimping can also be used to
form a strong bond between the workpiece and a non-metallic component.
Sometimes, a similar deformity created for reasons other than forming a join may
also be called a crimp.
SCREWDRIVER:
A screwdriver is a tool for driving screws and rotating other machine
elements with the mating drive system. The screwdriver is made up of a head or tip,
which engages with a screw, a mechanism to apply torque by rotating the tip, and
some way to position and support the screwdriver. A typical hand screwdriver
comprises an approximately cylindrical handle of a size and shape to be held by a
human hand, and an axial shaft fixed to the handle, the tip of which is shaped to fit a
particular type of screw. The handle and shaft allow the screwdriver to be
positioned and supported and, when rotated, to apply torque. Screwdrivers are
made in a variety of shapes, and the tip can be rotated manually or by an electric
motor or other motor. A screw has a head with a contour such that an appropriate
screwdriver tip can be engaged in it in such a way that the application of sufficient
torque to the screwdriver will cause the screw to rotate.
PROCEDURE:
1. Connect a 1Volt peak-peak,1KHz sine wave signal from the function
generator to the horizontal input of the CRO.
2. Adjust the vertical and horizontal gains properly for good display.
RESULT:
Familiarized testing instruments and commonly used tools.
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EX. NO: 04
DATE:
DRAWING OF CIRCUIT DIAGRAMS USING BIS/IEEE SYMBOLS,
INTERPRET DATA SHEETS OF DISCRETE COMPONENTS AND ICS
AIM:
To draw electronic circuits using BIS/IEEE symbols and to interpret
datasheets of various electronic components.
COMPONENTS AND EQUIPMENTS REUIRED:
Proteus software
THEORY:
Proteus is one of the most famous simulators. It can be used to simulate
almost every circuit on electrical fields. It is easy to use because of the GUI interface
that is very similar to the real Prototype board. Moreover, it can be used to design
Print Circuit Board (PCB).
Example of Proteus software window
1. Proteus tools.
a. Parts Browsing
Proteus has many models of electronic equipments such as logic gates, many kinds
of switches and basic electronic devices. These equipments can befounded by
clicking on
and then .
Then, a new window will pop up and wait for the part’s information as shown in
figure
Dept. of ECE, TEC, Vellarakkad
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Example of pick device page
Finding Steps:
1. Type information of the device such as “and gate” in the box 1
2. If some specific category is known, the device can narrow on focusing by selecting
catalogue in the box 2
3. After the information is put, the list of the related devices will appear in the box 3,
so that needed device can be choose here and then click “OK” button to confirm the
selection as shown in Figure below.
Example of picking device page(2)
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b. Power Supplies and input signal generators
All of the electrical circuits require power supplies. The power supply for
devices is represented on proteus because the schematic will be too complicated to
understand for simulation section. Therefore, the power supplies will be need as
input power for a system. Moreover, all of the input generators, such as ac, dc, and
pulse, are contained in this category and it will be shown when are clicked. In
addition, “Ground” will not contain in this groups because it is not input signal but it
is just a terminal junction. Therefore it will be group in the terminal ( ) category as
shown in Figure.
In addition, there is another input that usually be used in digital circuit
designed system but it does not exist in real world as an equipment. It is called as
“LOGIC STATE”. It can be find in picking part section typing “logicstate” and pick it.
logic state
2. How to do the simulating
a)Placing Equipments
After selecting all the devices, now devices needed to be placed on the circuit sheet
(Grey sheet)and wiring before the simulation can be run by following these steps:
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1. Click on and select a first device that will be placed
2. Place mouse to wherever the device is preferred to be place and then click the left
button of the mouse. The device will be place. If it needed to be moved. Click the
right button of the mouse on the device symbol to select the part and then hold the
left button of the mouse and move the symbol to wherever it is needed to be places.
placing the parts
3. To wire the device together, click at the source pin of the device and then move
mouse cursor to the destination pin of the device. In this step the pink line will be
appear and it will be the wire of the circuit after click mouse on the destination pin
of the circuit
4. After wiring all of the devices and all input together, the simulation is ready to be
run by clicking on to run and to stop. However, to see the result measurements
needed to be added in the circuit.
b) Measuring Digital data
Actually, the digital result on proteus can be seen in small square at the pin of the
equipments and the state will be shown in 4 colors(red = logic “1”, Blue = logic “0”,
Grey = Unreadable logic and Yellow = Logic congestion). However, proteus build a
modules that can be used to show the logic in 2 ways.
1. Logic display
The display that proteus has for seeing logic value is called “logic-probe”. It has
2 sizes and these seizes have the same functions. And it can be found from “picking
devices” page
Logic Probe
Dept. of ECE, TEC, Vellarakkad
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2. Waveform display.
In the low frequency case, logic-probe is the easiest way for digital logic analysis
because human eyes can see the result of the simulation. Also, logic-probe also
works for high frequency system but human eyes cannot see the results. Therefore,
proteus creates digital logic analyzer for the high frequency jobs. To use the logic
analyzer on proteus following these steps,
1. Click on and place the voltage probe to the point the needed to measure. After
connect the probe to measured point, the probe will be named as identifier of the
measure point.
2. Click on and select “digital” from “Graphs” box then assign the are of digital
display. The Green screen will appear as measurement monitor
3. Clicking at the word “DIGITAL ANALYSIS” on the screen. New window will
appear as the expanded screen
4. Click on graph>> add trace, new pop up window will appear to add the measure
points needed on “Probe P1” (if many probes appear on the design, proteus may ask
to offer all probes adding) then click OK. The select probes will be added on the
screen.
5. To see the result of the design must be clicked to simulation for 1 second.
Datasheet of 1N4001
a. Diffused Junction
b. High Current Capability and Low Forward Voltage Drop
c. Surge Overload Rating to 30A P
d. Low reverse leakage current
Mechanical Data
• Case: DO-41
• Case Material: Molded Plastic. UL Flammability Classification Rating 94V-0
• Moisture Sensitivity: Level 1 per J-STD-020D
• Terminals: Finish - Bright Tin. Plated Leads Solderable per MIL-STD-202,Method
208
• Polarity: Cathode Band
• Mounting Position: Any
• Marking: Type Number
• Weight: 0.30 grams (approximate)
Dept. of ECE, TEC, Vellarakkad
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Datasheet of BC107
NPN General Purpose transistor Characteristics
1. Low current (max. 100 mA)
2. Low voltage (max. 45 V).
APPLICATIONS: General purpose switching and amplification
Dept. of ECE, TEC, Vellarakkad
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Datasheet of IC 7400
This device contains four independent gates each of which performs the logic NAND
function.
Maximum condition
1. Supply Voltage 7V
2. Input Voltage 7V
3. Operating Free Air Temperature Range 0°C to +70°C
4. Storage Temperature Range -65°C to +150°C
Dept. of ECE, TEC, Vellarakkad
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Datasheet of IC7408
This device contains four independent gates each of which performs the logic AND
function.
Absolute Maximum Ratings
 Supply Voltage 7V
 Input Voltage 7V
 Operating Free Air Temperature Range 0°C to +70°C
 Storage Temperature Range -65°C to +150°C
Dept. of ECE, TEC, Vellarakkad
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COST
ITEM Name
1n4001
BC107
IC7400
IC7408
Cost
1.50
14
21
21
PROCEDURE
1. Open proteus software
2. Draw the circuit diagram
3. Simulate and observe the output
Dept. of ECE, TEC, Vellarakkad
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CIRCUIT DIAGRAM
1. Diode Clipper
R=3.3k
2. NAND Gate operation using 7402 IIC
RESULT
Familiarized EDA tool and simulated various electronic circuits.
Dept. of ECE, TEC, Vellarakkad
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EX. NO: 05
DATE:
INTER-CONNECTION METHODS AND SOLDERING PRACTICE
AIM:
Study different inter-connection methods and soldering practice.
COMPONENTS AND EQUIPMENTS REUIRED:
Multimeter, Soldering iron, De-soldering pump, Pliers, Cutters, Wire
strippers, Tweezers, Crimping tool, Resistor, IC holder and breadboard, general
purpose PCB, RJ-45 connectors.
THEORY:
Breadboard:
A breadboard is used to build and test circuits quickly before finalizing any
circuit design. The breadboard has many holes into which circuit components like
ICs and resistors can be inserted.
The bread board has strips of metal which run underneath the board and
connect the holes on the top of the board. The top and bottom rows of holes are
connected horizontally while the remaining holes are connected vertically. To use
the bread board, the legs of components are placed in the holes. Each set of holes
connected by a metal strip underneath forms a node. A node is a point in a circuit
where two components are connected. Connections between different components
are formed by putting their legs in a common node. The long top and bottom row of
holes are usually used for power supply connections. The rest of the circuit is built
by placing components and connecting them together with jumper wires. ICs are
placed in the middle of the board so that half of the legs are on one side of the middle
line and half on the other.
Layout of metal strip under the breadboard
Wrapping:
Wire wrap is a method to construct electronic circuit boards. Electronic components
mounted on an insulating board are interconnected by lengths of insulated wire run
between their terminals, with the connections made by wrapping several turns
Dept. of ECE, TEC, Vellarakkad
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around a component lead or a socket pin. Wires can be wrapped by hand or by
machine, and can be hand-modified afterwards. It was popular for large-scale
manufacturing in the 60s and early 70s, and continues to be used for short runs and
prototypes. The method eliminates the design and fabrication of a printed circuit
board. Wire wrapping is unusual among other prototyping technologies since it
allows for complex assemblies to be produced by automated equipment, but then
easily repaired or modified by hand.
Wire Wrapping Tool
Close-up of a wire-wrap connection
Crimping:
Crimping was invented by Amp Incorporated in 1941 as a solderless method
for terminating wires and connectors. Crimping technologies enabled far more rapid
and consistent wire terminations compared to soldering.
Crimping tool
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1. Take cable and your RJ-45 connectors.
2. Strip 1 to 2 inches (2.5 to 5.1 cm) of the outer skin at the end of the cable wire
by making a shallow cut in the skin with a utility knife. Run the knife around
the cable, and the jacket should slide off easily. There will be 4 pairs of
twisted wires exposed, each of them a different color or color combination.
Orange-white striped and solid orange, Green-white striped and solid green,
Blue-white striped and solid blue and Brown-white striped and solid brown.
3. Fold each pair of wires backwards to expose the core of the cable.
4. Cut off the core and discard.
5. Straighten the twisted wires using 2 pair of tweezers. Grasp a wire beneath a
bend with 1 pair of tweezers, and use the other pair to gently straighten the
bend.
6. Arrange the untwisted wires in a row, placing them into the position, running
from right to left, in which they will go into the RJ-45 connector: Orange with
a white stripe, Orange, Green with a white stripe, Blue, Blue with a white
stripe, Green, Brown with a white stripe and Brown.
7. Trim the untwisted wires to a suitable length by holding the RJ-45 connector
next to the wires. The insulation on the cable should be just inside the bottom
of the RJ-45 connector. The wires should be trimmed so that they line up
evenly with the top of the RJ-45 connector.
8. Insert the wires into the RJ-45 connector, making sure that they stay aligned
and each color goes into its appropriate channel. Make sure that each wire
goes all the way to the top of the RJ-45 connector.
9. Use the crimping tool to crimp the RJ-45 connector to the cable by pressing
the jacket and cable into the connector so that the wedge at the bottom of the
connector is pressed into the jacket. Recrimp the cable once more to ensure
proper connection.
10. Follow the instructions above to crimp an RJ-45 connector to the opposite
end of the cable.
11. Use a cable tester to assure that your cable is working properly when both
ends are crimped.
Solder:
Traditional solder is an alloy (mixture) of tin and lead, typically 60% tin and 40%
lead. It melts at a temperature of about 200°C. Modern lead-free solder is an alloy of
tin with other metals including copper and silver. It melts at a temperature of about
220°C.Coating a surface with solder is called 'tinning' because of the tin content of
solder.
Desoldering:
At some stage it is required to desolder a joint to remove or re-position a
wire or component.
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Safety precautions:
1. Never touch the element or tip of the soldering iron.They are very hot (about
400°C) and will give you a nasty burn.
2. Take great care to avoid touching the mains flex with the tip of the iron.The
iron should have a heatproof flex for extra protection. An ordinary plastic
flex will melt immediately if touched by a hot iron and there is a serious risk
of burns and electric shock.
3. Always return the soldering iron to its stand when not in use. Never put it
down on your workbench, even for a moment.
4. 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.
5. Wash your hands after using solder. Traditional solder contains lead which is
a poisonous metal.
Preparing the soldering iron:
1. Place the soldering iron in its stand and plug in.The iron will take a few
minutes to reach its operating temperature of about 400°C.
2. Dampen the sponge in the stand. The best way to do this is to lift it out the
stand and hold it under a cold tap for a moment, then squeeze to remove
excess water. It should be damp, not dripping wet.
3. Wait a few minutes for the soldering iron to warm up, check if it is ready by
trying to melt a little solder on the tip.
4. Wipe the tip of the iron on the damp sponge.This will clean the tip.
5. 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 on the sponge.
PROCEDURE:
Soldering:
1.
2.
3.
4.
Hold the soldering iron like a pen, near the base of the handle.
Touch the soldering iron onto the joint to be made.
Feed a little solder onto the joint.
Remove the solder, then the iron, while keeping the joint still.Allow the joint
a few seconds to cool before you move the circuit board.
5. Inspect the joint closely. It should look shiny and have a 'volcano' shape. If
not, it required to reheat and feed in a little more solder. This time ensure
that both the lead and track are heated fully before applying solder.
Dept. of ECE, TEC, Vellarakkad
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Desoldering pump (solder sucker)
1.
2.
3.
4.
Set the pump by pushing the spring-loaded plunger down until it locks.
Apply both the pump nozzle and the tip of your soldering iron to the joint.
Wait a second or two for the solder to melt.
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.
RESULT:
Studied inter-connection methods using bread board, crimping tool and
done soldering practice successfully.
Dept. of ECE, TEC, Vellarakkad
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EX. NO: 06
DATE:
PRINTED CIRCUIT BOARDS (PCB)
AIM:
Design and fabrication of a single sided PCB for a simple circuit with manual
etching (Ferric chloride) and drilling.
COMPONENTS AND EQUIPMENTS REUIRED:
Single sided PCB, Double sided PCB, ferric chloride and driller.
THEORY:
A printed circuit board (PCB) mechanically supports and electrically connects
electronic components using conductive tracks, pads and other features etched from
copper sheets laminated onto a non-conductive substrate. PCBs can be single
sided (one copper layer), double sided (two copper layers) or multi-layer (outer and
inner layers). Multi-layer PCBs allow for much higher component density.
Conductors on different layers are connected with plated-through holes called vias.
Advanced PCBs may contain components - capacitors, resistors or active devices embedded in the substrate. FR-4 glass epoxy is the primary insulating substrate
upon which the vast majority of rigid PCBs are produced. A thin layer of copper foil
is laminated to one or both sides of an FR-4 panel. Circuitry interconnections is
etched into copper layers to produce printed circuit boards. Complex circuits are
produced in multiple layers.

Single side Laminate
One layer of copper. Normally the wire-leaded components
must be mounted on only one side of the PCB, with all the
leads through holes, soldered and clipped. It can also used to
mount the components on the track surface using Surface
Mount Technology (SMT) or Surface Mount devices (SMD).
Surface mount circuitry is generally smaller than
conventional. Surface mount is generally more suited to
automated assembly than conventional. In practice, most
boards are a mix of surface mount and conventional
components. This can have its disadvantages as the two
technologies require different methods of insertion and
soldering. Conventional circuitry is generally easier to debug
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and repair.

Double sided Laminate
Two layers of copper, one each side of the board. The
components must be mounted on only one side of the PCB but
you can also mount components on both sides of the PCB.
Normally only surface mount circuitry would be mounted on
both sides of a PCB. The components must be mounted using
both through-holes tecnology or Surface Mount Technology
(SMT) or Surface Mount devices (SMD). Conventional
circuitry is generally easier to debug and repair.

Multi-Layer
A PCB Laminate may be manufactured with more than two
layers of copper tracks by using a sandwich construction. The
cost of the laminate reflects the number of layers. The extra
layers may be used to route more complicated circuitry,
and/or distribute the power supply more effectively.
PTH process:
Through-hole technology, also spelled "thru-hole", refers to the mounting
scheme used for electronic components that involves the use of leads on the
components that are inserted into holes drilled in printed circuit boards (PCB)
and soldered to pads on the opposite side either by manual assembly (hand
placement) or by the use of automated insertion mount machines.
Processing Methods:
Steps involved in fabrication of PCB.
1. Base material cutting
2. Drilling
3. Through hole plating
4. Layer film generation
5. Solder resist film generation
6. Legend printing film (optional)
7. Laminating
8. Exposing
9. Spray developing
10. Etching process
11. Solder resist masking
12. Legend printing (optional)
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Base material cutting
Base material which is selected based on application, may be epoxy resin
(FR4), duroid (of required dielectric constant), is cut into the required size
Drilling
Holes are drilled through the board using an automated drilling machine. A
cnc drilling/milling machine, which is controlled by an Excellonfile with the hole
position data and alis of the labels of the required drill bits, is used to drill the holes,
to mill certain board contours and to produce multiple printed panel. The holes are
used to mount electronic components on the board and to provide a conductive
circuit from one layer of the board to another.
Through hole plating
Following drilling, the board is scrubbed to remove fine copper particles left
by the drill. After being scrubbed, the board is cleaned and etched to promote good
adhesion and then is plated with an additional layer of copper. Since the holes are
not conductive, electrolysis copper plating is employed to provide a thin continuous
conductive layer over the surface of the board and through the holes.
Layer film
For multilayer boards films must be produced according to the number of
layers. Powerful software tools generate a plotfile, whose data control a
photoplotter. After developing the films, they have to be inspected under table lamp
for any track breaks, line shortages or missing of any track.
Solder resist film
In order to ensure no shortings in the PCB due to formation of moisture, or
due to spreading of solder leads, the complete board except the pads are to be
soldered masked. This is done in CAD design tools and the photofilm is generated in
the photoplotter. Thenthe photofilm is developed.
Legend printing film (optional)
This is developed in order to ensure ease and fastness during soldering of
components. This is also designed in CAD system and the film is generated in the
photoplotter.
Laminating
By this process the drilled and plated‐through boards are laminated by
rolling under pressure a photo‐resist laminate on both sides of the board.
Exposing
After properly aligning films on the photoresist laminated board, the board is
exposed by a UV light on both sides in the UV exposure unit.
Spray developing
The exposed board is developed in a spray developer unit. The developer
solution is sprayed on both sides of the board by a spray rotating system.
Afterwards the rest of the non‐exposed laminate is removed by a rinsing process,
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whereas the exposed laminate is etch resistant and thus protects the circuit pattern
against etching
Etching process
In that process the UV nonexposed copper is etched. Afterwards the etch
resistant material over the tracks, pads of PCB is rinsed by means of a solvent attack.
Ferric Chloride
It's messy stuff but easier to get and cheaper than most
alternatives. It attacks any metal including stainless steel, so when
setting up a PCB etching area, use a plastic or ceramic sink. Use a
hexahydrate type of ferric chloride, which is light yellow, and
comes as powder or granules, which should be dissolved in warm
water until no more will dissolve. Adding a teaspoon of table salt
helps to make the etchant clearer for easier inspection.
Anhydrous ferric chloride is sometimes encountered, which is a
green-brown powder. Avoid this stuff if at all possible use
extreme caution, as it creates a lot of heat when dissolved always add the powder very slowly to water, do not add water to
the powder, and use gloves and safety glasses.It is seen that
solution made from anhydrous FeCl doesn't etch at all, if so, it is
required to add a small amount of hydrochloric acid and leave it
for a day or two. Always take extreme care to avoid splashing
when dissolving either type of FeCl. With fresh hot ferric chloride,
a PCB will etch in well under 5 minutes, compared to up to an
hour without heat or agitation. Fast etching also produces better
edge quality and consistent line widths. If a bubble tank is used, it
is required to agitate frequently to ensure even etching. Warm the
etchant by putting the etching tray inside a larger tray filled with
boiling water.
PROCEDURE:
1. Choose Board type and dimension- Single side Laminate
2. Draw the PCB layout-The PCB layout can be draw either manually or by ECAD
(Electronic - Computer Aid Design) software. One way to put a pattern on the
board is the direct draw approach using a resist pen. It's not a real choice but
it is used to make very low definition PCBs. The Pen must be a black
permanent marker. The pen technique relies on the waterproof nature of the
ink and the tapes as an impervious plastic, both of which prevent the etchant
from getting at the copper beneath, hence, all copper is etched away except
for where the pattern has been drawn. This is the quickest way to get a circuit
pattern on the board. Etching is probably the easiest and most cost effective.
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3. Etching is the process of chemically removing the unwanted copper from a
plated board. Make a mask or resist on the portions of the copper that you
want to remain after the etch. These portions that remain on the board are
the traces that carry electrical current between devices.
CIRCUIT DIAGRAM:
RESULT:
Designed and fabricated a single sided PCB for a simple circuit with manual etching
(Ferric chloride) and drilling.
Dept. of ECE, TEC, Vellarakkad
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EX. NO: 07
DATE:
ASSEMBLING OF ELECTRONIC CIRCUIT/SYSTEM ON GENERAL
PURPOSE PCB
AIM:
Assemble electronic circuit/system on general purpose PCB
1. Fixed voltage power supply
2. Square wave generator using IC 555 timer in IC base
3. Sine wave generation using IC 741 OP-AMP in IC base
4. RC coupled amplifier with transistor BC 107.
COMPONENTS AND EQUIPMENTS REUIRED:
Resistor, Capacitor, Diode, Zener diode, IC 555, IC 741, LM7812 and BC 107
THEORY:
1. Fixed voltage power supply
A regulated power supply is vital for any electronic appliance because the
semiconductor devices used in them have precise current and voltage ratings. Any
deviation from these rating can damage the devices. This circuit supplies a constant
DC output derived from the AC mains supply. The unregulated DC output is fixed to a
constant voltage level by using a voltage regulator. This circuit uses a 7805 linear
voltage regulator, capacitors and resistors along with a diode derived bridge
rectifier.
2. Square wave generator using IC 555 timer in IC base
The 555 Oscillator is another type of relaxation oscillator for generating
stabilized square wave output waveforms of either a fixed frequency of up to
500kHz or of varying duty cycles from 50 to 100%.
3. Sine wave generation using IC 741 OP-AMP in IC base
Oscillator is a circuit which generates output without any input. Oscillator can be
defined as a device that converts dc to ac. A Phase shift oscillator consists of an
Op-Amp as the amplifying stage and three RC cascaded networks as the feedback
circuit. The feedback circuit provides feedback voltage from the output back to the
input of the amplifier. The Op-Amp is used in the inverting mode, therefore any
signal that appears at the inverting terminal is shifted by 180o at the output. An
Dept. of ECE, TEC, Vellarakkad
EW/ LM 01
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additional 180o phase shift required for oscillation is provided by the 3 RC sectionseach section providing a Phase shift of 600. Thus the total phase shift around the
loop is 3600 (or 00 ).
4. RC coupled amplifier with transistor BC 107
A small signal amplifier is used to amplify all of the input signal with the
minimum amount of distortion possible to the output signal, in other words, the
output signal must be an exact reproduction of the input signal but only bigger
(amplified). To obtain low distortion when used as an amplifier the operating
quiescent point needs to be correctly selected. This is in fact the DC operating point
of the amplifier and its position may be established at any point along the load line
by a suitable biasing arrangement. The best possible position for this Q-point is as
close to the center position of the load line as reasonably possible, thereby
producing a Class A type amplifier operation, ie. Vce = 1/2Vcc.
CIRCUIT DIAGRAM:
1. Fixed voltage power supply
2. Square wave generator using IC 555 timer in IC base
Dept. of ECE, TEC, Vellarakkad
EW/ LM 01
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3. Sine wave generation using IC 741 OP-AMP in IC base
4. RC coupled amplifier with transistor BC 107
PROCEDURE:
1. Solder the components/equipment in general purpose PCB as shown in the
circuit diagram.
2. Switch ON the power supply.
3. Connect the output of the circuit to CRO through probes.
4. Sketch the output waveform by noting the time period and peak to peak
voltage of the output waveform.
RESULT:
Assembled electronic circuit/system on general purpose PCB and verified the
output waveform.
Dept. of ECE, TEC, Vellarakkad
EW/ LM 01
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INDEX
1. Familiarization/Identification of electronic components with specification
2. Testing of Electronic components
3. Familiarization/Application of testing instruments and commonly used tools
4. Drawing of electronic Circuit diagrams using BIS/IEEE symbols, interpret data
sheets of discrete components and ICs.
5. Inter-connection methods and soldering practice
6. Printed circuit boards(PCB)
7. Assembling of electronic circuit/system on general purpose PCB
i) Fixed voltage power supply with transformer,rectifier diode, capacitor
filter,zener/IC regulator
ii) LED blinking circuit using a stable multi-vibrator with transistor BC107
iii) Square wave generator using IC 555 timer in IC base
iv) Sine wave generation using IC 741 OP-AMP in IC base
v) RC coupled amplifier with transistor BC107
vi) AND and NAND gates in diode transistor logic
8. Familiarization of electronic systems
i.
ii.
iii.
iv.
v.
vi.
vii.
Setting up of a PA system with different microphones, loud speakers,
mixer etc.
Assembling and dismantling of desktop computer/laptop/mobile
phones.
Coil/Transformer winding.
Identify the subsystems of TV, DTH, CCTV, Cable TV, CRO, Function
generator
Screen printing and PCB pattern transfer
Soldering & de-soldering of SMD using hot air soldering station.
Introduction to robotics- Familiarization of components (motor,
sensors, battery etc.) used in robotics and assembling of simple robotic
configurations.
Dept. of ECE, TEC, Vellarakkad
EW/ LM 01
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Dept. of ECE, TEC, Vellarakkad