Electronic Circuits and Devices Lab Report: UCK Unit 22

Desklib provides solved assignments and past papers to help students succeed.

The London College
UCK
Unit22:Electro
nicCircuit and
Devices
Lab Report
electronic circuits and devices

ELECTRONIC CIRCUITS AND DEVICES 1

Table of Contents
LIST OF FIGURES..............................................................................3
OBJECTIVES....................................................................................4
INTRODUCTION............................................................................... 4
LO1: FINDING OUT THE OPERATIONAL FEATURES OF AMPLIFIERS.............5
Task # 1............................................................................................................................................................. 5
A. Kinds Of Amplifiers.................................................................................................................................. 5
B. Working Principle..................................................................................................................................... 8
C. Determining Voltage Gain......................................................................................................................... 9
D. Design Of Category A Amplifiers............................................................................................................ 10
E. Simulated Model Of Category A Amplifier:............................................................................................ 11
F. Influence Of Design Constraints:............................................................................................................. 11
G. Study And Assessment Of Amplifiers...................................................................................................... 12
LO2: EXAMINE THE KINDS AND INFLUENCES OF FEEDBACK ON AN
AMPLIFIER’S ENACTMENT................................................................14
Task 2.............................................................................................................................................................. 14
 Output Voltage Of Amplifier With Rf..................................................................................................... 14
 Summing Circuitry................................................................................................................................. 15
 A Simulated Model Of Summing Amplifier............................................................................................. 15
 Outcome Of Feedback Resistance On Gain And Performance................................................................16
 Examination And Evaluation Of Consequences......................................................................................17
LO3: OBSERVE THE PROCESS AND USES OF OSCILLATORS.......................18
Task 3.............................................................................................................................................................. 18
 Types And Applications Of Oscillators.................................................................................................... 18
ELECTRONIC CIRCUITS AND DEVICES 2

 Calculation Of Gain................................................................................................................................. 20
Calculation of Frequency:....................................................................................................................................20
 Assessing The Enactment Of Oscillator’s Circuit....................................................................................21
 A Simulated Model Of Oscillator............................................................................................................ 21
 Investigation And Evaluation Of Results................................................................................................. 22
LO4: APPLYING ANALYSIS TECHNIQUES TO ELECTRONIC CIRCUITS..........23
Task 4.............................................................................................................................................................. 23
 Comparison Of LM741 And Ideal OP-AMP........................................................................................... 23
 Parameters Of Operational Amplifier..................................................................................................... 23
 Simulated Model Of 741 Amplifier.......................................................................................................... 24
 Assessing The Practical Values And Values Obtained Through Simulation............................................24
CONCLUSION.................................................................................26
References........................................................................................................................................................ 27
ELECTRONIC CIRCUITS AND DEVICES 3

List Of Figures
Figure 1 Symbol of Op Amp...........................................................................................................4
Figure 2 Circuit Diagram Category A Amplifier and its operational characteristics.....................5
Figure 3 Circuit Diagram Category B Amplifier and its operational characteristics......................5
Figure 4 Circuit Diagram Category AB Amplifier and its operational characteristics...................6
Figure 5 Circuit Diagram Category C Amplifier and its operational characteristics......................6
Figure 6 given circuit of amplifier...................................................................................................8
Figure 7 Breadboard connections of operational amplifier.............................................................9
Figure 8 Simulation of category A amplifier...................................................................................9
Figure 9 Wave form of Category A amplifier...............................................................................10
Figure 10 Given op amp with Rf...................................................................................................11
Figure 11 Summing amplifier.......................................................................................................12
Figure 12 Armstrong amplifier......................................................................................................14
Figure 13 Circuit Diagram of Hartley Oscillator..........................................................................15
Figure 14 Circuit diagram Colpitts Circuit...................................................................................15
Figure 15 Simulation and graph of oscillator................................................................................17
Figure 16 Simulated circuit of LM741.........................................................................................19
ELECTRONIC CIRCUITS AND DEVICES 4

Objectives
 To understand working principle of amplifiers and oscillators
 To study their types and applications
 To calculate gain and output voltage of Op-Amps and Oscillators
 To simulate and analyze different op-amp and oscillator circuits
Introduction
Amplifiers are the electronic devices that can boost up a signal’s amplitude without undergoing
an alterations in its waveform, frequency etc. The primary running features of an ultimate
amplifier are its linear nature, sign advantage, performance and power . They are the most
typically cast-off devices in electronic systems. General symbol of operational amplifier is given
beneath:
Oscillators are basically used to generate oscillatory signals and are generally used or employed
in commonplace circuits, reaching from radios to TV transmitters.
ELECTRONIC CIRCUITS AND DEVICES 5
Figure 1 Symbol of Op Amp

LO1: Finding Out The Operational Features Of Amplifiers
Task # 1
A. Kinds Of Amplifiers
Amplifiers are categorized into different types on the basis of input given and the
output take out of it.These include:
 Voltage amplifier
 Current amplifier
 Trans-conductance amplifier
 Power amplifier
Voltage Amplifier:
The cause of voltage-amplifier is to create larger heft of the output voltage waveform. This is the
simplest form of amplifiers and are being used in many common applications.
Current Amplifier:
The function of a current amplifier is to sort the peak of the output signal grander than that of the
input given to it, though the heft of the yield voltage may possibly be superior or minor than the
input. This does not affect the design of amplifier.
Trans Conductance Amplifier:
This amplifier increases the Trans conductance of the circuit. Trans conductance is presented as
ratio of Io to Vi served to the amplifier.
Power Amplifier:
A power- amplifier is designed for supplying excessive power. Exclusive importance must be
paid in scheming such amplifiers because the energy intemperance at some phase in the junction
increases its temperature and subsequently do away with it.
Classification of Power Amplifiers:
It is further classified into different classes on the basis of their construction and operating
characteristics. These are given as follows:
Category A Amplifier:
ELECTRONIC CIRCUITS AND DEVICES 6

These are the utmost cast-off category of amplifier design as they employ just one switching
transistor inside their amplifier scheme in such a way so it is never pushed into its cut-off or
saturation regions consequently permitting it to conduct current over the entire cycle.
Category B Amplifier:
It is formed with 2 active maneuvers which remain in on condition during 1/2 of the real cycle
which is 180 degrees of the phase.2 maneuvers deliver mutual current get-up-and-go for the load.
It’s a little different than Class A amplifiers. The main advantage of these amplifiers is the
reduction in heat dissipation and a bit in increase in effectiveness as paralleled to class A
amplifiers. It has a limitation i.e. Crossover alteration (El-Maleh et al, 2016).
Category AB amplifiers:
ELECTRONIC CIRCUITS AND DEVICES 7
Figure 2 Circuit Diagram Category A Amplifier and its operational characteristics
Figure 3 Circuit Diagram Category B Amplifier and its operational characteristics

The AB class is presently considered to be the supreme cast-off kinds of audial strength
amplifier layout. These amplifiers are combined version of a category B and category A
amplifiers .In this class both transistors are permitted to remain on at the same interval across the
waveforms thus eliminating category B amplifier issues of distortion of signals. It is presented in
the figure below:
Category C Amplifier:
Category C amplifiers have the greatest efficiency upto 80% but linearity is quite poor than all of
the above mentioned amplifiers. Conduction angle is around 90
Other Common Amplifier Classes:
Class D,F and G are other common classes of amplifiers.
ELECTRONIC CIRCUITS AND DEVICES 8
Figure 4 Circuit Diagram Category AB Amplifier and its operational characteristics
Figure 5 Circuit Diagram Category C Amplifier and its operational characteristics

Class D acts as a nonlinear switching device. Class F amplifiers give very high efficiency only if
infinite tuning is used. Class G is basically an advancement in AB class amplifiers. It gives
reduced power losses.
Applications Of Amplifiers:
Following are some of the important applications of amplifiers:
i. Power amplifiers are used in devices that require a lot of amplification stages.
ii. Class B amplifiers can be used in radio frequency amplification like AM and FM
modulation.
iii. Operational-AMPs can be used as voltage comparator
iv. These devices can be employed in selective inversion circuits
v. OP-AMP are able to be used like a voltage follower.
vi. One of its application is in devices that require active rectifiers
vii. These can be employed as integrator circuit.
viii. Video amplifiers are used to video quality in small TV s placed on vehicles.
ix. Buffer amplifiers can be used as impedance matching machines
x. DC amplifiers are used where low frequency signals are to be amplified.
xi. Some amplifiers can be employed in ultrasonic screening ,scanning and remote
control systems
xii. For radio transmission of high power, Class C amplifiers are suitable to use.
xiii. Switching type power amplifiers are cast-off in industries for governing actuators like
servo or DC motors.
B. Working Principle
Following are the working principles of diverse kinds of amplifiers:
 Type A amplifier:
In these type of amplifiers, input must be fed at the base and amount produced is obtained
at the collector.
They remain in on condition over the entire cycle which on one hand provides better
high frequency but on the other hand it becomes a cause of noise and signal distortion.
 Type B amplifier
ELECTRONIC CIRCUITS AND DEVICES 9

Category B amplifier is constructed by using 2 active devices. They turn bias separately
during +ve and –ve 1/2 cycles of sine waves so we get complete signal at the output. So
these amplifiers provide improved efficiency and less heat dissipation.
 Type AB amplifier
 AB amplifier has the characteristics of the 2 A and B amplifiers.
 It employs intermediary conduction angle of the two categories.
 They have the identical structure of class B amplifier with active devices which conducts
all through 1/2 of the cycles separately but each tool biased in another way in order that
they don’t get absolutely OFF during the crossover moment. Their efficiency remains
intermediate between the efficacies of category A and B amps.
 Type C amplifier
This works in 2 different operating modes i.e. tuned and un-tuned. During tuned mode it
is used as a clamper while in un-tuned mode it gives high distortions. It works by using
conduction angle less than 180 degrees (Kirby et al, 2015).
C. Determining Voltage Gain
Data:
R 1+R 2=10 k
RL=50 Ω ,Vsource=1 V ,
Iout=200 miliA
Calculation:
ELECTRONIC CIRCUITS AND DEVICES 10
Figure 6 given circuit of amplifier

Output voltage:
Vo=(1+ R 2/ R 1)Vs
Vo=50∗200 m=10 V
Gain : A =Vo /Vs
¿ 10 V /1V =10
D. Design Of Category A Amplifiers
Fix the transistor and 4 resistors on the breadboard in the first place. Then connect the power
supply and measure voltages across base, emitter & collector either they are correct or not. Make
sure that the voltages across capacitor is half the amount of supply voltages. The worth of RL
and Re must be determined and a nearby possible value must be chosen. The circuitry set up is
shown below:
Output Voltages values should not be drastic. So use a voltage Multi-meter to check this, If the
values are within normal range then there is no need to make any change and our connections
has been accurately done.
ELECTRONIC CIRCUITS AND DEVICES 11
Figure 7 Breadboard connections of operational amplifier