PROJECT: COLPITTS OSCILLATOR

By

Sayed Mujtaba ME-113030Adeel Anwar ME-113039

A Project submitted to theElectronic Department

In partial fulfillment of the requirements for the degree ofBS (MECHANICAL ENGINEERING)

Faculty of EngineeringMohammad Ali Jinnah University

Islamabad

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 ContentsChapter 1…………………………………..

.INTRODUCTION.....................................viiColpitt 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.....................................................ixLITERATURE REVIEW...........................ix2.1 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.....................................................xiTOOLS AND TECHNIQUES....................xi3.1 Hardware used with technical specifications:.............................................xi

Resistor.........................................................................................xi

Capacitor......................................................................................xi

Transistor.....................................................................................xi

Inductor........................................................................................xi

3.1.1 Resistors:............................................................................................xi

3.1.2 Capacitors:........................................................................................xii

3.1.3 Transistor:........................................................................................xiv

3.1.4 Inductor:............................................................................................xv

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3.1.5 DMM:................................................................................................xv

3.1.6 Oscilloscope:....................................................................................xvi

3.1.7 Ferric chloride:................................................................................xvii

3.1.8 Kerosene oil:...................................................................................xvii

3.1.9 Driller:.............................................................................................xvii

3.1.10 Solder:...........................................................................................xvii

3.2 Software(s), simulation tool(s) used........................................................xvii

3.2.1 Pispice software:.............................................................................xvii

3.2.2 Proteus software:.............................................................................xvii

3.3 Summary:................................................................................................xviii

Chapter 4...................................................xixMETHODOLOGIES................................xix4.1 Design of the investigation/Algorithms/ Hardware:.................................xix

4.2 Analysis procedures:.................................................................................xix

4.3 Implementation procedure:.......................................................................xix

4.3.1 Details about hardware:..............................................................xix

4.3.2 Details about software/ algorithms:...........................................xix

4.4 Verification of functionalities:...................................................................xx

4.5 Details about simulation / mathematical modeling:...................................xx

4.6 Summary:...................................................................................................xx

Chapter 5.................................................xxiRESULTS AND ANALYSIS...................xxi5.1 Presentation of the findings:.....................................................................xxi

5.1.1 Hardware results:.......................................................................xxi

5.1.2 Software results:........................................................................xxii

5.2 Discussion of the findings:.......................................................................xxii

5.2.1 Comparison with initial GOAL:...............................................xxii

5.3 Recommendations:...................................................................................xxii

5.5 Summary:.................................................................................................xxii

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Chapter 6...............................................xxiiiCONCLUSION......................................xxiiiREFERENCES....................................................................................................xxiv

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Chapter 1

INTRODUCTIONColpitt 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 Theoretical bases and 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 2LITERATURE REVIEW

2.1 Related Technologies.

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 Related Projects:

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.

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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 Related Studies:

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.

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Chapter 3

TOOLS AND TECHNIQUES3.1 Hardware used with technical specifications:

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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Resistor Color Codes:

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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), simulation tool(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 4METHODOLOGIES

4.1 Design of 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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4.4Verification of 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 / mathematical modeling:

As the formula

F = 1

2π √LC

F = 1

2π √L( c1c 2c 1+c2

)

F = 1

2π √220uH ( .001uF× .001uF.001uF+.00 1uF

)

F = 1

2π √220uH ( 1uF×1uF1uF+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 ANALYSISThis 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:-

5.1.2 Software results:

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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 Discussion of the 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

CONCLUSIONColpitts 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.

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REFERENCES1. www.seas.upenn.edu

2. www.google.com

3. onlinelibrary.wiley.com

4. wps.prenhall.com.

5. www.sbmicro.org.

6. www.allaboutcircuits.com/worksheets/oscill

7. wps.prenhall.com/chet_paynter

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