Power Amplifier Project Report
Power Amplifier Project Report
Power Amplifier Project Report
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Submitted by
Muhammad Awais (Reg. No.: 2014-EE-414)
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Contents
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Lab Project Report
Power Amplifier
Theory and Principles
Amplifier
Figure 1
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This is because this type of amplifier is used in circuits that perform
mathematical algorithmic functions, or operations on input signals to obtain
specific types of output signals. A typical op-amp has differential inputs (one
inverting, one non-inverting relative to the output) and one output. An
idealised op-amp has the following characteristics:
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Figure 2
Typically, the emitter region is heavily doped compared to the other two layers,
whereas the majority charge carrier concentrations in base and collector layers
are about the same.By design, most of the BJT collector current is due to the
flow of charges injected from a high-concentration emitter into the base where
there are minority carriers that diffuse toward the collector, and so BJTs are
classified as minority-carrier devices.
Types of Transistor:
There are two types of bi polar junction transistors .
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Figure 3
Cascaded System(Connections)
The two-port systems approach is particularly useful for cascaded systems such
as that appearing in the following figure, where AV1, AV2, AV3, and so on, are
the voltage gains of each stage under loaded conditions.That is, Av1 is
determined with the input impedance to AV2 acting as the load on AV1.For
AV2, AV1 will determine the signal strength and source impedance at the input
to AV2 .The total gain of the system is then determined by the product of the
individual gains as follows:
No matter how perfect the system design, the application of a succeeding stage
or load to a two-port system will affect the voltage gain. Therefore, there is no
possibility of a situation where AV1, AV2, and so on, are simply the no-load
values.
Figure 4
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Darlington System(Connections)
A very popular connection of two bipolar junction transistors for operation as
one super beta transistor is the Darlington connection shown in the following
figure. The main feature of the Darlington connection is that the composite
transistor acts as a single unit with a current gain that is the product of the
current gains of the individual transistors. If the connection is made using two
separate transistors having current gains of beta1 and beta2, the Darlington
connection provides a current gain of
Figure 5
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Project Work & Performance
Apparatus
Resistors
o 1K
o 47K
o 2.2K
o 10K
Capacitors
o 1000 F
o 47 F
o 10 F
o 1000 pF
Diodes
Bridge Rectifier
PCB sheet
DC supply(24 volts)
TIP31 TRANSISTOR
2N3904 TRANSISTOR
Speaker
Resistors
A resistor is a passive two terminal electrical component implements electrical
resistance as a circuit element. Resistors act to reduce current flow, and, at the
same time, act to lower voltage levels within circuits. In electronic circuits,
resistors are used to limit current flow, to adjust signal levels, bias active
elements, and terminate transmission lines among other uses. High-power
resistors, that can dissipate many watts of electrical power as heat, may be used
as part of motor controls, in power distribution systems, or as test loads
for generators. Fixed resistors have resistances that only change slightly with
temperature, time or operating voltage. Variable resistors can be used to adjust
circuit elements (such as a volume control or a lamp dimmer), or as sensing
devices for heat, light, humidity, force, or chemical activity.
Resistors are versatile tool for the limitation of current. They belong to a passive
category of elements. Resistors come in different sizes and their rating are
described using a sequence of specific colors known as color codes. A typical
resistor is shown in the figure below.
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Figure 6
Capacitors
Diodes
Figure 7
Bridge Rectifier
The half-wave rectifier chopped off half our signal. A full-wave rectifier does more clever
trick: it flips the - half of the signal up into the + range. When used in a power supply, the
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full-wave rectifier allows us to convert almost all the incoming AC power to DC.
Figure 8
This type of single phase rectifier uses four individual rectifying diodes connected in a closed
loop bridge configuration to produce the desired output. The main advantage of this bridge
circuit is that it does not require a special centre tapped transformer, thereby reducing its size
and cost. The single secondary winding is connected to one side of the diode bridge network
and the load to the other side as shown below.
Figure 9
Figure 10
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PCB sheet
Figure 11
DC Supply
Speaker
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A Speaker is a slang term for loud speaker driver designed to produce low
frequency sounds, typically from around 40 hertz up to about a kilohertz or
higher. The most common design for a woofer is the electro dynamic driver,
which typically uses a stiff paper cone, driven by a voice coil which is
surrounded by a magnetic field. The voice coil is attached by adhesives to the
back of the speaker cone. The voice coil and magnet form a linear electric
motor. When current flows through the voice coil, the coil moves in relation to
the frame according to Fleming's left hand rule, causing the coil to push or pull
on the driver cone in a piston-like way. The resulting motion of the cone creates
sound waves as it moves.
Figure 12
If an amplifier with 50 watts of rated output power into 8-ohm speakers, and
that combination produces reasonably clean and loud music, then by doubling
the amplifier power to 100 watts per channel, the system would then play twice
as loud. Although it's not the easiest thing to comprehend, doubling the
amplifier power does not double the loudness. Because effect of R L is very
necessary. Therefore, a 100 watt amplifier will produce sound only slightly
louder than a 50-watt amplifier. If we want to increase loudness to a reasonable
level then we have to apply RL from 12 to 15 ohm instead of 8 ohm.
Speaker power
The best method when matching speakers to amplifiers is to use the "RMS"
power ratings instead of Max/Peak power ratings. It's important to note that
most speaker manufactures publish two different power ratings:
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No. of Each Speaker Rating Total Speaker Rating Recommended Amplifier Power
Speakers (RMS) (RMS) (RMS)
1 100 watts 100 watts 30-100 watts
2 100 watts 200 watts 60-200 watts
3 100 watts 300 watts 90-300 watts
4 100 watts 400 watts 120-400 watts
Table 1
TIP31 TRANSISTOR
A TIP31 is a standard type of NPN bipolar junction transistor used for medium
power applications.A TIP31 is complementary to a TIP32 PNP bipolar
transistor. TIP31 transistors are designated as TIP31A, TIP31B, TIP31 to
indicate increasing collector-base and collector-emitter breakdown voltage
ratings.
Figure 13
2N3904 transistor
The 2N3904 is a common NPN bipolar junction transistor used for general
purpose low-power amplifying or switching applications. The type was
registered by Motorola Semiconductor in the mid-sixties, together with the
complementary PNP type 2N3906, and represented a significant
performance/cost improvement, with the plastic TO-92 case replacing metal
cans. It is designed for low current and power, medium voltage, and can operate
at moderately high speeds.
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Experimental Procedure
PCB Design
PCB design is usually done by converting your circuits schematic
diagram into a PCB layout using PCB layout software. There are many
cool open source software packages for PCB layout creation and design.
Figure 14
Figure 15
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STEP 2: Cutting the copper plate for the circuit board
Cut the copper board according to the size of layout using a hacksaw or a cutter.
Figure 16
Figure 17
STEP 4: Ironing the circuit from the paper onto the PCB plate
After printing on glossy paper, we iron it image side down to copper side.
Heat up the electric iron to the maximum temperature.
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Put the board and photo paper arrangement on a clean wooden
table (covered with a table cloth) with the back of the photo paper facing
you.
Using pliers or a spatula, hold one end and keep it steady. Then put the hot
iron on the other end for about 10 seconds. Now, iron the photo paper all
along using the tip and applying little pressure for about 5 to 15 mins.
Pay attention towards the edges of the board you need to apply pressure,
do the ironing slowly.
Doing a long hard press seems to work better than moving the iron around.
Here, the heat from the iron transfers the ink printed on the glossy paper to
the copper plate.
Figure 18
After ironing, place printed plate in luke warm water for around 10
minutes. Paper will dissolve, then remove paper gently. Remove the
paper off by peeling it from a low angle.
Figure 19
Gently move the plastic box to and fro so that etching solution reacts with the
exposed copper. The reaction is given as
Cu + FeCl3 CuCl3 + Fe
Figure 20
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STEP 6: Cleaning, disposing and final touches for the circuit board
Be careful while disposing the etching solution, since its toxic to fish and other
water organisms.
A few drops of thinner (nail polish remover works well) on a pinch of cotton
wool will remove completely the toner/ink on the plate, exposing the copper
surface. Rinse carefully and dry with a clean cloth or kitchen paper. Trim to
final size and smoothen edges with sandpaper.
Figure 21
Now, drill holes using a PCB driller like this: PCB driller and solder all cool
components.
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Performance of Project
Circuit diagram
Figure 22
Proteus
Figure 23
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Workbench
Figure 24
PCB SCREEN(Diptrace)
Figure 25
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Figure 26
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Workbench Verification
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Table
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Result(Project Images)
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