3 stage fm transmitter

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By: jyotsna.alapati (34 month(s) ago)

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3 Stage FM Transmitter : 

3 Stage FM Transmitter GUIDED BY:- k.v.satyanarayana SWARNANDHRA INSTITUTE OF ENGINEERING & TECHNOLOGY DEPARTMENT OF ELECTRONICS AND COMMUNICATION TEAM MEMBERS:- P.GOPI KRISHNA PRASAD (07EM1A0463) CH.RAJ KUMAR (07EM1A0449) R.RAVI TEJA (07EM1A0439) D.V.S.S.REVANTH (07EM1A0404) A.BHAVANI SHANKAR (08EM5A0405) (HEAD OF THE DEPT.)

ABSRACT : 

ABSRACT F.M. TRANSMITTER HAS 3 R.F STAGES .A VARIABLE FREQUENCY OF VHF OSCILLATOR,C CLASS DRIVER STAGE AND FINAL POWER AMPLIFIER FREQUENCY OF TRANSMITTTER CAN BE SET WITH IN 88-108MHZ. F.M. BROAD CAST BY ADJUSTING FIRST TRIMMEROR SPACING BETWEEN OSCILLATOR COIL TURNS.

INTRODUCTION : 

INTRODUCTION RF OSCILLATOR OPERATES AROUND 100MHZ ELECTRET MICROPHONE FIRST AMPLIFICATION STAGE OSCILLATOR STAGE FINAL AMPLIFICATION STAGE DIPOLE ANTENNA

CIRCUIT DIAGRAM OF FM TRANSMITTER : 

CIRCUIT DIAGRAM OF FM TRANSMITTER

ASSEMBLY INSTRUCTIONS : 

ASSEMBLY INSTRUCTIONS COMPONENTS MAY BE ADDED TO THE PCB IN ANY ORDER . THE TWO 100n CAPACITORS ON PCB HAVE 0.2 AND 0.1 SPACING. A CONNECTION IS REQUIRED FROM THE MIDDLE OF L1 TINNED COPPER WIRE COIL TO THE PAD MARKED TAP NEXT TO THE COIL. MAKE SURE NONE OF THE LOOPS OF THE COIL ARE TOUCHING THE LOOP NEXT TO IT. PAY SPECIAL ATTENTION TO THE SOLDER JOINT IN CASE ALL THE ENAMEL HAS NOT BEEN REMOVED.

TRIMMER CAPACITANCE : 

TRIMMER CAPACITANCE THE SLOTS INSIDE THE TRIM CAP ARE SHAPED LIKE THE HEAD OF AN ARROW . TO GET THE MAXIMUM CAPACITENCE VALUE ARROW IS POINTED TO 12 O’ CLOCK POSITION,THE 180 o’ TURN GIVES MINIMUM RATED VALUE. WE CAN CHANGE THE FREQUENCY BY ALTERING THE SPACE BETWEEN THE COILS OF L1.

Slide 7: 

THE 10pf CERAMIC CAPACITOR IN PARALLEL WITH THE RED TRIM CAP. WE CAN TUNE Tx IN THE 98 MHZ TO 105 MHZ RANGE OF COMMERCIAL FM BAND . THE YELLOW TRIM CAP IS USED TO TUNE THE Tx TO A CLEAR PART OF BAND. WHITE CAN BE USED TO FINE TUNE THE Tx TO THE DESIRED FREQUENCY. SPREAD THE L1 COIL WIDE APART. TRIMMER CAPACITANCE

Slide 8: 

POOR SOLDERING IS THE MOST LIKELY REASON THAT THE CIRCUIT DOES NOT WORK. CHECK ALL THE SOLDERING JOINTS CAREFULLY UNDER A GOOD LIGHT. CHECK ALL THE COMPONENTS ARE PLACED IN THE CORRECT POSITION OR NOT ON THE PCB. CHECK WEATHER YOU REALLY SPREAD OUT THE COILS OF L1? USE A MULTIMETER FOR CHECKING PURPOSE. TROUBLE SHOOTING

Slide 9: 

A PEAKING CIRCUIT IS SIMPLY AN RF DETECTOR THAT USES DIODES TO CHARGE A CAPACITOR. THE VOLTAGE ACROSS THE CAPACITOR IS SET TO A RANGE 2 0R 20 VOLTS. THE OUTPUT SHOULD BE CONNECTED DIRECTLY TO THE VOLT METER. THE INPUT TO THE PEAKING CIRCUIT IS SOLDED TO THE ANTENNA WIRE HOLE OF LENGTH 5 cm. PEAKING CIRCUIT

Slide 10: 

THE FM TRANSMITTER WAS DESIGNED TO OPERATE FROM 9v DC, HOWEVER YOU CAN INCREASE THE OUTPUT POWER BY USING A 12v OR 15v DC SUPPLY. IF YOU TRY THIS THEN THE VALUES OF SOME RESISTANCE WILL HAVE TO CHANGE. OPERATING VOLTAGE

Slide 11: 

ONCE YOU HAVE ASSEMBLED YOUR TRANSMITTER YOU WILL HAVE TO TUNE IT TO A FREQUENCY ON FM BROADCAST BAND. TUNE YOUR FM RECEIVER TO A PART OF THE DIAL WHERE YOU CAN NOT HEAR ANY RADIO STATIONS. BY TAPPING THE MICROPHONE YOU WILL HEAR YOUR SIGNAL, IF YOU DON’T THEN CONTINUE TUNING UNTIL YOU CAN. USE THE WHITE TRIM CAPACITOR TO FINE TUNE THE TRANSMITTER TO THE RECEIVER. TUNING THE FM TRANSMITTER

Slide 12: 

EDUCATIONAL PURPOSE. HOME INTERCOM. NATURE RESEARCH. COMMERCIAL. USES & ADVANTAGES LOW COST. EASY TO CARRY. HIGH MOBILITY. HIGH S/N RATIO. FUTURE SCOPE:- YOU CAN GET MORE RANGE BY REDUCE R5,R7 TO 100R,47R AND INCREASE C7 TO 470P. USING OF YAGI’S IN PLACE OF DIPOLE ANTENNA TO IMPROVE COVERAGE AREA.

Slide 13: 

HENCE WE CONCLUDE THAT BY USING THE FM TRANSMITTER WE CAN TRANSMIT AUDIO SIGNAL S UPTO SOME EXTENT AND WE CAN INCREASE THE COVERAGE AREA BY CHANGING SOME SPECIFICATIONS IN THE CIRCUIT. CONCLUSION

Slide 15: 

T H A N ‘ Q ,