ACKNOWDGEMENT
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ABSTRACT The main aim of our project Frequency Modulator Receiver is to operate a FM receiver with a simple circuit consist of two simple ICs, resistor, antenna, capacitor, diode. An FM radio wave receiver includes a diversity antenna system responsive to signal strength and noise levels. The signal strength and noise detectors generate representative signals that are compared with a threshold value for determining the input to a control for the antenna switch alternately connecting two or more antennas to the front end of the FM receiver. The present invention provides an adaptive threshold for each of the signal strength and noise signals so that the switching is limited to significant changes in signal strength and noise levels. In the preferred embodiment, the noise level threshold is adapted as a function of the modulation level of the audio composite signal delivered from the FM detector to the stereo decoder of the FM receiver.
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LIST OF FIGURES
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NAME
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CIRCUIT DIAGRAM
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BLOCK DIAGRAM
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PROJECT OVERVIEW : Broadcast band frequency modulation (FM) radio was invented to solve existing problems with noise and fidelity on the amplitude modulation (AM) broadcast band. Thus, the first FM receivers were quite complex in design, employing a super heterodyne converter, a wideband IF, a limiter stage, and a discriminator. Unlike the first AM radio sets, the earliest FM radio sets did not use the simplest possible methods for receiving signals. Although the title alludes to simplicity, these radio designs are not uniformly simple. These designs generally have low component counts, however the design or construction my have been far from simple.The purpose of this project is to make FM circuit simple and to get output frequency in wide range. The F.M. band covers 88-108 MHz. There are signals from many radio transmitters in this band inducing signal voltages in the aerial. The RF amplifier selects and amplifies the desired station from the many. It is adjustable so that the selection frequency can be altered. This is called TUNING. In cheaper receivers the tuning is fixed and the tuning filter is wide enough to pass all signals in the F.M. band. • The selected frequency is applied to the mixer. • The output of an oscillator is also applied to the mixer. • The mixer and oscillator form a FREQUENCY CHANGER circuit. • The output from the mixer is the intermediate frequency (i.f.) • The i.f. is a fixed frequency of 10.7 MHz.
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PROJECT DESCRIPTION We are immensely pleased to put forth the following introduction. The aim of this project work is to design, construct and test the Frequency Modulator receiver. The circuit consists of IC CXA1619BS, CTC810, diodes, resistors, antenna, capacitors, and transformer. There are two main sections. Firstly the signal frequency is received from antenna and it is stored in IC CXA1619BS using capacitors. Secondly the signal is amplified using IC CTC810. Using the tuner the selected frequency can be obtained from IC CXA1619BS. The FM receiver is designed using the popular Sony chip CXA1619BS used for AM/FM receiver circuits. The chip is a 30 pin dual-in–line package with the following functional blocks: · Front-end block (RF amplifier, mixer , oscillator) · IF stage · FM discriminator · AF Power amplifier The transmitted signal is picked up by a high gain and high directivity Yagi –Uda antenna designed to pick signals around 145 MHz frequencies. The signal from the antenna is fed first to IC CXA1619BS which suppresses adjacent channels and allows only the selected high frequency signal.
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CXA1619BS:
CXA1619BM/BS is a one-chip FM/AM radio IC designed for radio-cassette tape recorders and headphone tape recorders, and has the following functions. Features
•Small number of peripheral components. • Low current consumption (VCC=3 V) For FM: ID=5.8 mA (Typ.) For AM: ID=4.7 mA (Typ.) • Built-in FM/AM select switch. • Large output of AF amplifier. EIAJ output=500 mW (Typ.) when VCC=6 V, load impedance 8 ½ Functions FM section • RF amplifier, Mixer and OSC (Incorporating AFC variable capacitor). •IF amplifier •Quadrature detection • Tuning LED driver AM section • RF amplifier, Mixer and OSC (with RF AGC) • IF amplifier (with IF AGC) •Detector • Tuning LED driver AF section •Electronic volume control Absolute Maximum Ratings (Ta=25 °C) •Supply voltage VCC 14 V 11
• Operating temperature Topr –10 to +60 °C • Storage temperature Tstg –50 to +125 °C • Allowable power dissipation PD 700 mW (CXA1619BM) PD 1000 mW (CXA1619BS) Recommended Operating Conditions Supply voltage VCC 2 to 7.5 V (CXA1619BM) VCC 2 to 8.5 V (CXA1619BS) CTC810: The CTC810 is a monolithic integrated circuit in a 12-lead quad in-line plastic package, intended for use as a low frequency class B amplifier. FEATURES
*A wide range of supply voltages (4 to 20V) *High output current (up to 2.5A) *High efficiency (75% at 6W output) *Very low harmonic and cross-over distortion *Built-in thermal shut down protection circuit
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The FM receiver circuit consists of two sections • Receiving section • Amplifying section RECEIVING SECTION:
This section consists of antennas, Ic CXA1619BS,tuner,capacitance. ANTENNAS :
The antenna receives to receive all the frequency signals. The received frequency signals are then passed to Ic CXA1619BS. IC CXA1619BS: C X A 1 6 1 9 B M / B S is a one-chip FM/AM radio IC d e s i g n e d for radio-cassette tape recorders and headphone tape recorders. This Ic is used to store the all frequency signals received from antennas. It has following features • Small number of peripheral components. · • Low current consumption (VCC=3 V) • For FM : ID=5.8 mA (Typ.) CAPACITANCE:
Once the capacitor is charged, the voltage on the capacitor is used to kill the oscillations of the circuit. (Technically, the capacitor voltage shifts the operating point of the amplifier to reduce its gain and stop the oscillations.) When the oscillations stop, the capacitor discharges (through a resistor). Once the capacitor is discharged, the oscillations begin again. TUNER:
The tuner is used to select the required frequency.
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AMPLIFYING SECTION:
This section consists of Ic CTC810,capacitance Ic CTC810:
The CTC810 is a monolithic integrated circuit in a 12-lead quad in-line plastic package, intended for use as a low frequency class B amplifier. It amplifies the signal and produces noise free amplified signal.
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RESISTORS Aresist o r is a two-terminal electronic component designed to oppose an electric current by producing a voltage drop between its terminals in proportion to the current, that is, in accordance with Ohm's law:V =IR. The resistance R is equal to the voltage dropV across the resistor divided by the currentI through the resistor. Resistors are characterized primarily by their resistance and the power they can dissipate. Other characteristics include temperature coefficient, noise, and inductance. Practical resistors can be made of resistive wire, and various compounds and films, and they can be integrated into hybrid and printed circuits. Size, and position of leads are relevant to equipment designers; resistors must be physically large enough not to overheat when dissipating their power. Variable resistors, adjustable by changing the position of a tapping on the resistive element, and resistors with a movable tap ("potentiometers"), either adjustable by the user of equipment or contained within, are also used. Resistors are used as part of electrical networks and electronic circuits.There are special types of resistor whose resistance varies with various quantities, most of which have names, and articles, of their own: the resistance of thermistors varies greatly with temperature, whether external or due to dissipation, so they can be used for temperature or current sensing. Resistors, like diodes and relays, are another of the electronic parts that should have a section in the installer's parts bin. They have become a necessity for the mobile
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electronics installer, whether it be for door locks, praking lights, timing circuits, remote starts, LED's, or just to discharge a stiffening capacitor. Resistors "resist" the flow of electrical current. The higher the value of resistance (measured in ohms) the lower the current will be. Resistors are color coded. To read the color code of a common 4 band 1K ohm resistor with a 5% tolerance, start at the opposite side of the GOLD tolerance band and read from left to right. Write down the corresponding number from the color chart below for the 1st color band (BROWN). To the right of that number, write the corresponding number for the 2nd band (BLACK) . Now multiply that number (you should have 10) by the corresponding multiplier number of the 3rd band (RED)(100). If a resistor has 5 color bands, write the corresponding number of the 3rd band to the right of the 2nd before you multiply by the corresponding number of the multiplier band. If you only have 4 color bands that include a tolerance band, ignore this column and go straight to the multiplier
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CAPACITORS Acapacito r is a passive electrical component that can store energy in the electric field between a pair of conductors (called "plates"). The process of storing energy in thecapacitor is known as "charging", and involves electric charges of equal magnitude, but opposite polarity, building up on each plate. A capacitor's ability to store charge is measured by its capacitance, in units of farads. Capacitors are often used in electric and electronic circuits as energy-storage devices. They can also be used to differentiate between high-frequency and low-frequency signals. This property makes them useful in electronic filters. Practical capacitors have series resistance, internal leakage of charge, series inductance and other non-ideal properties not found in a theoretical, ideal, capacitor.Capacitors are Ocasionally referred to as condensers. In theory, the dielectric can be any non-conductive substance. However, for practical applications, specific materials are used that best suit the capacitor's function. Mica,ceramic, cellulose, porcelain, Mylar, Teflon and even air are some of the nonconductive materials used. The dielectric dictates what kind of capacitor it is and for what it is best suited. Depending on the size and type of dielectric, some capacitors are better for high frequency uses, while some are better for high voltage applications. Capacitance also depends on the dielectric constant of the dielectric material separating the plates. The standard units of Capacitance, farad(F) microfarad: µF (1 µF = 10-6 F) nanofarad: nF (1 nF = 10-9 F) Pico farad: pF (1 pF = 10-12 F)
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DIODES Adiode is a two-terminal device ( thermionic diodes may also have one or two ancillary terminals for a heater).Diodes have two active electrodes between which the signal of interest may flow, and most are used for their unidirectional electric current property. The varicap diode is used as an electrically adjustable capacitor. The directionality of current flow most diodes exhibit is sometimes generically called the rectifying property. The most common function of a diode is to allow an electric current to pass in one direction (called the forward biased condition) and to block the current in the opposite direction (the reverse biased condition)
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APPLICATIONS FM receiver is used • For receiving reception signals of TV signals • For reception signals of FM-radio signals. • The invention is particularly suited for multi-media applications. The invention also relates to a multi-media apparatus incorporating such a receiver. • Radio communication and broadcasting.
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ADVANTAGES The following are advantages of FM receiver: • No need of tuned circuit • Simple circuit that can be implemented in integrated circuits. • Low cost • Less maintenance • Noise interference is minimum1
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CONCLUSION
Our project “FM receiver” helps to know about the FM circuit and working of circuit. Our project gives the simplified circuit of FM receiver by using two chips IC CXA1619BS and CTC810. It also helps to know about the basic things of FM receiver. It has some more advantages compared to other FM receivers such as simplified circuit, less cost etc. We can use in both radio and TV reception signals.
SUGGESTION
Our project will be more easy to know about the FM receiver and sure that this project will have a recognition and we hope it in right direction.
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WEBSITE: www.pechorin.com www.industrycommunity.com www.electronicsforu.com www.doctonics.com
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