FM TRANSMITTER
B.E. ELECTRONIC CIRCUIT DESIGN
Prepared By
Muhammad Hassan 9341
Nabeel Iqbal
Project Advisor
Sir Zeeshan Nazar
College of Engineering
PAF-Karachi Institude of Economic And Technology
Karachi
ABSTRACT
A fm transismitter is a circuit which developed frequency modulated signal using transistor. This circuit is basically a radio system which aid with antenna and increase the electromagnetic signal. In fm transmission they based on frequency range of 88MHz to 108MHz.When the input audio signal is applied to the transistor and the output signal is modulate and set the resonant frequency.
When we set the resonant frequency we change the capacitance value. After set the resonant value we connect to oscillator.
TABLE OF CONTENTS
Abstract .iTable Of Contents .iiList oF Figures .iiiCHAPTER ONE
INTRODUCTION …1
CHAPTER TWO
LITERATURE REVIEW …1
CHAPTER THREE
Method And Material 1-1.4
Battery ………1.1
Mic ..1.1
Resistor …1.2
Capacitor ……..1.2
Inductor …1.3
Trimmer capacitor .. 1.3
Transistor 1.4
Calculation .1.4
CHAPTER FOUR
Block Diagram ……..2
Schematic Diagram .2
CHAPTER 5
Conclusion .3
LIST OF FIGUREFig.1 Battery 1.1
Fig.2 Mic ..1.1
Fig. 3 Resistor ..1.2
Fig.4 Capacitor 1.2
Fig.5 Inductor ..1.3
Fig.6 Trimmer Capacitor .1.3
Fig.7 Transistor ….1.4
Fig.8 Block Diagram .2
Fig.9 Schematic Diagram ..3
CHAPTER 1
INTRODUCTION
The FM transmitter is a signal transistor circuit. In the telecommunication the frequency modulation (FM) transfer the information of different frequency of carrier wave according to message signal. Mostly FM transmitter used VHF radio frequencies of 87.5 MHz to 108 MHz to transmit and receive the FM signal.
CHAPTER 2
LITERATURE REVIEW
It had been exceed to need information over a long distance. In, over time different attempt had been made and not to justify this need, but to finish it ease. In beginning of human history the wired telephone in the eighteen forte (1840) and some decade later at the drawn of 21st century and the used of radio wave is the wireless communication system. In other thing, it enable the human voice for long distance using with carrier wave at a modulated frequency of 87.5MHz-108MHz and received on a suitable FM receiver.
CHAPTER 3
METHOD AND MATERIAL
In the ciruit (fig 1) shows that the FM transmitter circuit and used of electrical and electronic components in this circuit.
1: Battery (9v) 2: Mic
3: Resistor 4: Capacitor
5: Inductor 6: Trimmer Capacitor
7: Transistor 8: Antenna
To consider the microphone is to understand the signals which inside the mic and there is a presence of capacitive sensor. Its produce when the vibration is produce for air pressure and Ac signal. The formation of the oscillating tank circuit is done by the transistor of 2N3904 by using inductor and variable capacitor. The transistor which is used in the circuit is an NPN transistor and generally used for amplification purpose. If the current is passed at the inductor L1 and variable capacitor then the tank circuit will oscillate at the resonant carrier frequency of the fm modulation.
1: BATTERY
In our circuit is used for power supplier.
Figure 1
2: MIC
A device which convert energy from one to another.
Figure 2
3: RESISTOR
Resistor is a resistive purpose. Its basically used for all circuit. In our circuit we also used for resistive purpose.
Figure 3
4: CAPACITOR
Capacitor is used for storing charge in form of field, separated by an insulator. In other word we describe the capacitor as a component which has ability to store energy in form of electrical charge.
Figure 4
5: INDUCTOR
A inductor which store electrical energy in to magnetic energy. When electricity passes the coil from left to right its will generate a magnetic field in the form of clock direction.
Figure 5
6: TRIMMER CAPACITOR
It also called a variable capacitor.It has a facility to convert capacitance value, but frequently once variation is suffiently.
Figure 6
TRANSISTOR
A transistor is a electronic component which work two different jobs which is Amplification and switching. In our circuit we used transistor as amplification.
Figure 7
CALCULATION
STEP 1
FORMULA
F=1/ 2*pi*root*(l*c)
STEP 2
L=0.1uH
C=25pf
Pi=3.142
F=100MHz
CHAPTER 4
BLOCK DIAGRAM
To
ANTENNA
Modulator
Microphone
Audio Per-
Amplifier
ANTEENA
Oscillator
RE-Amplifier
Figure 8
MICRO PHONE
Its a type of transduce which convert energy from one to another. Its convert sound wave in to audio signal.
AUDIO PRE-AMPLIFIER
In audio pre amplifier the weak signal of input in to output signal and strong from noise and tolerance and also strong for further processing ,and then sending to microphone, without doing this its make distorting.
MODULATOR
To include voice information if anoter wave is need to be imposed called input signal, on the top of carrier wave. This process of imposing is for input signal in to carrier wave is called modulator.
OSCILLATOR
An oscillating electronic signal its produce a sine wave and square wave.It covert direct current (Dc) for power supply to alternate current (Ac) signal.
RF-AMPLIFIER
A radio frequency amplifier is only amplifying signal which is used to increase the amplitude. It also used as a receiver to amplify the signal and enable receiver to work.
ANTEENA
The radio wave which is passes through air at a speed of light. A antenna produce electric current to recreate the original signal.
SIMULATION CIRCUIT
Figure 9
CHAPTER 5
CONCLUSION
In this project we have seen operation of our lesson, which is fm modulation, oscillator, transmission and wireless communication and more. If signal modulation voltage is (0V) the carrier frequency remain constant which depent on transmission frequency and if signal voltage is increases the carrier frequency also increase the signal reach to +ve peak and carrier frequency is maximum. If the signal voltage is decreases the carrier frequency also decrease and the signal reach to 0 peak and carrier frequency is minimum.