FM TRANSMITTERA mini project that is submitted in partial fulfillment of the requirement for the award of the degree ofBACHELOR OF TECHNOLOGY IN ELECTRONICS AND COMMUNICATION ENGINEERING

Submitted byK.Siva Ranjani K.Ramya T. Anusha A. Syamala priya 10NA1A0402 10NA1A0407 10NA1A0443 10NA1A0458Under the guidance of

S.RAM KUMAR,M.Tech

LINGAYAS INSTITUTE OF MANAGEMENT AND TECHNOLOGY (Approved by AICTE, NEW DELHI & Affiliated to JNTUK, Kakinada)

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CONTENTSABSTRACT INTRODUCTION OPERATION CIRCUIT DIARAM COMPONENTS USED ADVANTAGES APPLICATIONS CONCLUSIONS

ABSTRACTAn FM Transmitter is a portable device that plugs into the headphone jack or output port

of a portable audio or video device, such as a portable media player, CD player, or satellite radio system. The sound is then broadcast through the transmitter, and plays through an FM broadcast band frequency.

INTRODUCTION Frequency modulation (FM) is a technique for wireless transmission of information where the frequency of a high frequency carrier is changed in proportion to message signal which contains the information. FM was invented and developed by Edwin Armstrong in the 1920s and 30s.

OPERATIONThis Circuit is very simple and uses few components. Main part of the circuit is RC ( Resistance Capacitor )circuit to produce Radio frequency at required Frequency band . A FM transmitter helps to connect an MP3 player with a car or a home stereo system through its radio receiver. It physically connects to the MP3 player and then broadcasts a short FM transmission of the songs playing on the MP3 player.

Once it is plugged into the MP3 player, the

transmission frequency on the FM transmitter is set to a FM station that is not used in that area. The FM receiver is then tuned to the FM transmission station and the music on the MP3 player can be heard via the car or home stereo speakers. "FM transmitter" can also refer to high powered broadcast equipment used by pirate radio and licensed broadcast stations.

CIRCUIT DIAGRAM :

COMPONENTS REQUIRED:

MAINLY USEDARIAL

Resistor.The resistor is the most common electronic component and

is used to limit and control the voltage and current in an electronic circuit.Variable resistor is used to restrict the current through

the MIC.. Capacitors.A capacitor is a passive element and it is a two-terminal

electrical component used to store energy in an electric field.

A small button type variable capacitor with a values in pF can be used to adjust the resonant frequency of the

Transistor.Transistor means transfer resistor i.e., signals are transferred from low resistance circuit into high resistance circuit. Transistor is not a critical part of the circuit, but selecting a high frequency / low noise one contributes the sound quality and range of the transmitter.

circuit.

Condenser microphoneThe condenser microphone, invented at Bell Labs in 1916 by E. C. Wente is also called a capacitor microphone or electrostatic microphone capacitors were historically called condensers. Radio frequency[RF] condenser microphones use a low RF voltage. The condenser MIC is used to pick up the sound signals.

AntennaAn antenna (or aerial) is an electrical device which converts electric currents into radio waves, and vice versa. An antenna can be used for both transmitting and receiving. The length of the antenna is very important to transmit the signals in the suitable range. For the circuit mentioned above, a 25-27 inches long antenna is sufficient.

ADVANTAGES:This circuit uses only single Transistor but good voice quality. On benefit of this is that it removes the hassle of the listener from having to stay chained to a desktop PC to listen to Internet radio.

APPLICATIONS : One common use of an FM transmitter is to play music from an MP3 player through the speakers of a car. A car traveling behind one with a FM transmitter can have its radio set to the same station and listen to the same transmission.

CONCLUSION:The FM-transmitter plugs into the audio output of audio devices and converts the audio output into an FM radio signal, which can then be picked up by appliances such as car or portable radios. Continuous tuning is achieved with a variable capacitor. Usually 87.5 108.0 MHz is used to transmit and receive the FM signals.15

Technical datas: Supply voltage : 1.1 - 3 Volts 1.8 mA at 1.5 Volts

Power consumption : Range :

30 meters max. at 1.5 Volts

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