2. PROJECT: COLPITTS OSCILLATOR
By
Sayed Mujtaba ME-113030
Adeel Anwar ME-113039
A Project submitted to the
Electronic Department
In partial fulfillment of the requirements for the degree of
BS (MECHANICAL ENGINEERING)
Faculty of Engineering
Mohammad Ali Jinnah University
Islamabad
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ABSTRACT
This is the report of our semester final project of the Circuit lab .This
report will give the reader an overview about the steps which are involved
in the making of a Colpitt oscillator. The project is about the making of
Colpitt oscillator that will generate approximately 1 MHz frequency. In
which the following components capacitor, inductor, resistors and
transistor were used. First, the circuit is implemented on PSPICE to test
the circuit whether it giving the correct value or not. Then it was
implemented on breadboard. The frequency and waveform on
oscilloscope were accurate. For making PCB design the software PCB
wizard has been used. For testing the circuit oscilloscope was used. It
showed the output of circuit and showed the waveform of approximately
1 MHz.
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Table of Contents
Chapter 1…………………………………...
INTRODUCTION ...................................... vii
Colpitt Oscillator:....................................................................................................vii
Overview:................................................................................................................vii
1.1 Purpose of the project: ...............................................................................viii
1.2 Applications of the Project:........................................................................viii
1.3 Theoretical bases and Organization:..........................................................viii
Chapter 2....................................................... ix
LITERATURE REVIEW............................ ix
2.1 Related Technologies.................................................................................. ix
2.1.1 Metal detector: ................................................................................... ix
2.2 Related Projects: ......................................................................................... ix
Hartley Oscillator:....................................................................................... ix
2.3 Related Studies:............................................................................................x
2.4 Summary:.....................................................................................................x
Chapter 3....................................................... xi
TOOLS AND TECHNIQUES.................... xi
3.1 Hardware used with technical specifications:............................................. xi
Resistor......................................................................................... xi
Capacitor ...................................................................................... xi
Transistor .................................... Error! Bookmark not defined.
Inductor ........................................................................................ xi
3.1.1 Resistors:............................................................................................ xi
3.1.2 Capacitors: .........................................................................................xii
3.1.3 Transistor: .........................................................................................xiii
3.1.4 Inductor:............................................ Error! Bookmark not defined.
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3.1.5 DMM:................................................................................................xiv
3.1.6 Oscilloscope:..................................................................................... xv
3.1.7 Ferric chloride:.................................. Error! Bookmark not defined.
3.1.8 Kerosene oil: ..................................... Error! Bookmark not defined.
3.1.9 Driller:............................................... Error! Bookmark not defined.
3.1.10 Solder:............................................. Error! Bookmark not defined.
3.2 Software(s), simulation tool(s) used .......................................................... xv
3.2.1 Pispice software: ............................................................................... xv
3.2.2 Proteus software:............................................................................... xv
3.3 Summary:...................................................................................................xvi
Chapter 4.................................................... xvii
METHODOLOGIES ................................ xvii
4.1 Design of the investigation/Algorithms/ Hardware:.................................xvii
4.2 Analysis procedures:.................................................................................xvii
4.3 Implementation procedure: .......................................................................xvii
4.3.1 Details about hardware: .............................................................xvii
4.3.2 Details about software/ algorithms: ...........................................xvii
4.4 Verification of functionalities:.................................................................xviii
4.5 Details about simulation / mathematical modeling:.................................xviii
4.6 Summary:.................................................................................................xviii
Chapter 5................................................... xix
RESULTS AND ANALYSIS................... xix
5.1 Presentation of the findings: ......................................................................xix
5.1.1 Hardware results: ........................................................................xix
5.1.2 Software results:.......................................................................... xx
5.2 Discussion of the findings:......................................................................... xx
5.2.1 Comparison with initial GOAL: ................................................. xx
5.3 Recommendations:..................................................................................... xx
5.5 Summary:................................................................................................... xx
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Chapter 1
INTRODUCTION
Colpitt Oscillator:
A Colpitts oscillator is a discrete LC oscillator that uses a pair of tapped
capacitors and an inductor to produce regenerative feedback.
Combination of inductor and capacitors determine frequency of
oscillator. It is type of feedback LC oscillator where feedback is supplied
capacitively. Colpitt oscillator is a device that consists of inductor and
capacitor that will generate frequency with the help of feedback signal.
The frequency is generally determined by the inductor and the two
capacitors.
Overview:
Colpitt Oscillator is a device that is used to produces the frequency. This
project gives the frequency approximately 450 kHz by using inductor of
220µH and capacitors of 102 and 103.
Circuit diagram of Colpitt Oscillator:
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1.1 Purpose of the project:
The purpose of project was base on making the Collpitt oscillator that is
use to produce frequency. A Colpitts oscillator is the electrical dual of a
Hartley oscillator.
1.2 Applications of the Project:
The Colpitt Oscillator will generate fixed frequency so this project can be
use in different appliances of electronic like metal detector and other
appliances in which frequency of 1MHZ was required. This project can
also make variable by replacing the fixed capacitor to variable capacitor.
1.3 Theoreticalbasesand Organization:
As Colpitt is pre-define design so that make a good feedback circuit to
attain the require frequency. Using transistor as voltage divider biased
with the resistor mention above frequency of 1MHz. In the pre define
circuit of the colpitt there is two capacitor grounded and one inductor.
The required frequency is obtained across the inductor. This is the part of
tank circuit.
Summary:
In this chapter we explain about project and the apparatus which were
used in the making of project and the applications of this project and the
theory of project and little introduction about the apparatus that was used
in this project. Also explain the some important applications of the
Colpitt Oscillator. As the colpitt oscillator is basically use to generate the
frequency so specific values of instrument was used to generate 1MHZ
frequency.
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Chapter 2
LITERATURE REVIEW
2.1 RelatedTechnologies.
2.1.1 Metal detector:
Metal detector is a device which responds to metal that may not be
readily apparent. The simplest form of a metal detector consists of an
oscillator producing an alternating current that passes through a coil
producing an alternating magnetic field. If a piece of electrically
conductive metal is close to the coil, eddy currents will be induced in the
metal, and this produces an alternating electric field of its own. If another
coil is used to measure the electric field, the change in the magnetic field
due to the metallic object can be detected.Metal detector used colpitt
oscillator to indicate the induction of metals. It is based on beat frequency
oscillator.
2.2 RelatedProjects:
Hartley Oscillator:
Hartley oscillator is similar to colpitt oscillator except the phase shift
consists of two inductors and only one capacitor. The frequency can be
easily be varied by varying the inductance. It is not suitable for low
frequency because high inductance value will be required.
10. x
Crystal Oscillator:
A crystal oscillator is an electronic oscillator circuit that uses the
mechanical resonance of a vibrating crystal of piezoelectric material to
create an electrical signal with a very precise frequency. This frequency is
commonly used to keep track of time (as in quartz wristwatches), to
provide a stable clock signal for digital integrated circuits, and to stabilize
frequencies for radio transmitters and receivers. The most common type
of piezoelectric resonator used is the quartz crystal, so oscillator circuits
incorporating them became known as crystal oscillators, but other
piezoelectric materials including polycrystalline ceramics are used in
similar circuits.
2.3 RelatedStudies:
There are different books and different websites to get maximum
application of this project and got number of application. Some important
application of this project and other related circuit of the oscillator is
mention in this report.
2.4 Summary:
In this chapter the relative study about the project and relative circuit of
colpitt was explained. Mention about the Hartley Oscillator and also draw
the basic circuit of Hartley Oscillator and the difference between the
Colpitt and Hartley Oscillator and also discussed about the application of
colpitt oscillator in different field and electronic things.
11. xi
Chapter 3
TOOLS AND TECHNIQUES
3.1 Hardware used with technicalspecifications:
Resistor
Capacitor
Op amp
3.1.1 Resistors:
A resistor is a passive two-terminal electrical component that implements
electrical resistance as a circuit element. The current through a resistor is
in direct proportion to the voltage across the resistor's terminals. This
relationship is represented by Ohm's law.
In this project four resistors R1, R2, and R3 are used. In which
R1=120kΩ
R2=100kΩ
R3=20kΩ
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3.1.2 Capacitors:
capacitor is a passive two-terminal electrical component used to store
energy in an electric field. The forms of practical capacitors vary widely,
but all contain at least two electrical conductors separated by a dielectric.
C1 = 0.1uF
3.1.3 Op amp:
An operational amplifier (op-amp) is a DC-coupled high-gain
electronic voltage amplifier with a differential input and, usually, a
single-ended output. An op-amp produces an output voltage that is
typically hundreds of thousands of times larger than the voltage
difference between its input terminals.
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The circuit symbol for an op-amp is shown to the right, where:
V+: non-inverting input
V−: inverting input
Vout: output
VS+: positive power supply
VS−: negative power supply
The power supply pins (VS+ and VS−) can be labeled in different ways
Often these pins are left out of the diagram for clarity, and the power
configuration is described or assumed from the circuit.
3.1.5 DMM:
A multi meter is an electronic measuring instrument that combines
several measurement functions in one unit. A typical multi meter would
include basic features such as the ability to measure voltage, current,
resistance, and Diode voltage. Multi meters may use analog or digital
circuits analog multi meters (AMM) and digital multi meters. Analog
instruments are usually based on a micro ammeter whose pointer moves
over a scale calibrated for all the different measurements that can be
made; digital instruments usually display digits, but may display a bar of
a length proportional to the quantity being measured. Digital multi meters
have all but replaced analog moving coil multi meters in most situations.
Analog multi meters are still manufactured today, but only by relatively
few manufacturers.
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3.1.6 Oscilloscope:
An oscilloscope, previously called an oscillograph, and informally known
as a scope, CRO (for cathode-ray oscilloscope), or DSO (for the more
modern digital storage oscilloscope), is a type of electronic test
instrument that allows observation of constantly varying signal voltages,
usually as a two-dimensional graph of one or more electrical potential
differences using the vertical or y-axis, plotted as a function of time
(horizontal or x-axis). Many signals can be converted to voltages and
displayed this way. Signals are often periodic and repeat constantly, so
that multiple samples of a signal which is actually varying with time are
displayed as a steady picture. Many oscilloscopes (storage oscilloscopes)
can also capture non-repeating waveforms for a specified time, and show
a steady display of the captured segment.
3.2 Software(s), simulationtool(s) used
3.2.1 Pispice software:
Pispice is useful software for biased analysis for the circuits. Pispice is
useful to determine the voltage across each component and then compare
it with the reading that measure with the help DMM. Pispice is used to
see the output wave form.
3.2.2 Proteus software:
Proteus software is used to see and find the waveform of our circuit.
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3.3 Summary:
The details of tools used in this project explained in this chapter. The
tools are able to make this project perfect and the specific value was also
given in this chapter that was used in project. These tools help for output
of the circuit. The virtual DMM are used to see the wave. The
oscilloscope was used on which the waveform has display. So generally
the value of all tools or instrument is given and also tell about the
behavior of circuit in different from like on pispice and on proteous.
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Chapter 4
METHODOLOGIES
4.1 Designof the investigation/Algorithms/ Hardware:
The colpitt is a pre define circuit so have to less work in the investigation
of the circuit and making its logic. But prefer to configure the transistor in
voltage divider biased. As knowing that transistor work and behavior in
voltage divider biased prefer this. Hardware used in project was
transistor, capacitor and resistors, which were mention in above chapter.
4.2 Analysis procedures:
Hard and difficult process of the project is analysis of the project after
making it on this hardware. As measure the current and voltage by using
DMM at different point of the circuit and by processing that analysis the
output frequency that the output of circuit was correct or not. For that
divide the circuit in different parts and measure the output of those parts
help for easy analysis.
4.3 Implementation procedure:
Implementation process made after the complete analysis of the circuit.
Draw the circuit first on the helping software make it confirm that the
circuit is 100% in working condition. Implement it by using the apparatus
mention above.
4.3.1 Details about hardware:
Hardware used in this project was transistor, resistors and capacitors
whose value is mention in the chapter 1.
4.3.2 Details about software/ algorithms:
Different software are used in this project, which are
1) Pispice software.
2) Proteus software.
3) MultiSim.
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4.4Verificationof functionalities:
As the functionalities of the project was to produce the frequency of 450
KHz. So its functionalities was that the project was produced the AC
waveform across the inductor. As verify it by using the oscilloscope for
waveform and also for frequency.
4.5 Details about simulation / mathematicalmodeling:
As the formula
F =
1
2𝜋√𝐿𝐶
F =
1
2𝜋√𝐿(
𝑐1𝑐2
𝑐1+𝑐2
)
F =
1
2𝜋√220𝑢𝐻(
.001𝑢𝐹×.001𝑢𝐹
.001𝑢𝐹+.001𝑢𝐹
)
F =
1
2𝜋√220𝑢𝐻(
1𝑢𝐹×1𝑢𝐹
1𝑢𝐹+1𝑢𝐹
)
F= 454 KHz
4.6 Summary:
In this chapter methodology of the project was explained. Complete
analysis of circuit on software that was used for this project and output
analysis of the project on the oscilloscope. The expression used for the
output frequency across the inductor, which is the main part of the
project. This chapter was about the analysis and the implementation of
the project from the software to hardware and its complete methodology
and its functionalities, verification and simulation and complete
investigation.
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Chapter 5
RESULTS AND ANALYSIS
This chapter was explained the following result and the analysis of the
circuit.
Software Results
Breadboard circuit Results.
PCB circuit Results.
5.1 Presentation of the findings:
5.1.1 Hardware results:
As making project on PCB it give output frequency of 480 KHz as
the input of 5v was given to circuit. The hardware and software
values are approximately equal there was little bit difference in the
Hardware result.
Oscilloscope Results:-
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5.1.2 Software results:
As in the previous chapter explained about the software used in the
making of this project and got different values but the difference was so
small. Used proteus Software which gives the frequency at any point you
want, the result of the software was 450 KHz,
5.2 Discussionofthe findings:
Finding the result obtained from the circuit by analysis and try to find the
error if it’s done.
Analysis the circuit, as 5v was given to circuit and than 2 resistors one
connected to collector and second to base and the diode configuration
was voltage divider biased, and then the main circuit which was define by
Colpitt, As 2 capacitor and inductor known as Tank Circuit come and
take output frequency across the inductor.
5.2.1 Comparison with initial GOAL:
As initially claimed was too achieved the variable frequency about 450
KHz to 1 MHz, but cannot arrange the variable capacitor of 1nF to 1uF,
so variable jacket is used in project. Using jacket it is easy to change the
capacitor value.
5.3 Recommendations:
Expert in circuit making software.
Ride over colpitts oscillator circuit.
Ride over Resonance frequency.
5.5 Summary:
This chapter is about the results and analysis of the circuit. As the main
overcome of the circuit and its output on the software and explanation
about its result on hardware and our recommendation to other about the
Colpitt Oscillator and also telling about the initial goal, comparison of
hardware and software results and limitation and recommendation.
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Chapter 6
CONCLUSION
Colpitts oscillators are similar to the shunt fed Hartley oscillator circuit
except the Colpitts oscillator, instead of having a tapped inductor, utilizes
two series capacitors in its LC circuit.
The main circuit part is two capacitors and inductor. The main problem
that was faced in this project is about the output frequency and calculated
frequency. With very hard work and team work this project are able to
take output of desire frequency. Different type of software has been used
before making the circuit on hardware to check the circuit is working or
not. After this the circuit of project was making on the breadboard. Check
its output frequency across the inductor. Trainer and DMM were used to
check the output frequency. Many problems were faced during its
making. Main problem was time issue and the time limit of the lab on
which all process has been done. As conclusion to this project, it was
good project to help us to understand of RCL circuits.
