Medium power FM transmitter circuit

john January 27, 2014 76 Comments

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Description.
This is the circuit diagram of a moderate power FM transmitter circuit employing two transistors.The voice signals picked by the microphone will be amplified by the transistor Q1.The second transistor is wired as an oscillator operating in the FM band.The output of T1 is given to the base of T2.T2 performs the modulation also.The tank circuit comprising of components L1 and C6 determines the frequency of the signal, and can be varied by adjusting C6.The capacitor C7 couples the FM signal to the antenna.

Circuit diagram with Parts list.

fm-transmitter-circuit

Notes.

  • You can assemble the circuit on a general purpose PCB.
  • The circuit can be powered from a9V PP3 battery.
  • The Antenna A1 can be a 1M long wire.
  • The inductor L1 can be made by making 6 turns of 0.8mm enameled copper wire on a 5.5mm diameter/4.5mm length plastic former.
  • With a matching antenna and proper tuning this transmitter can have range upto 100meters.
Comments
  • ECE
    August 15, 2015

    What is the operating frequency of this project?

  • October 28, 2014

    sir..how can i found which frequency is transmit by this transmitter….plzzzz help me…this is my minor project

    • seetharaman
      October 30, 2014

      broadcast band 88 to 108 mhz

  • October 28, 2014

    hello sir….this project is not work and i cant find any fault so plzzzzzzzz help me….

  • danish
    October 11, 2014

    i made this circuit on breadboard but it is not tuned plz anyone can help me?

  • amit
    June 14, 2014

    Can i use 0.5uF electrolitic capcitor in place of C3 (0.5uF Ceramic)

    • Seetharaman
      June 17, 2014

      Hi Amit It has to be ceramic or it can be solid tantalum bead type. not wound tubular capacitors, which has inductive component also buit in.

  • Tabat
    February 7, 2014

    What type of crystal oscillator can I use to replace the tank circuit with? Pls I need a reply with the frequency.

    • Victor
      June 14, 2014

      hmmmmm i dont know much but fm frequency range is 88-108 MHz

  • naser
    February 4, 2014

    hi. if I use mp3 player out put for this circuit (change Mic with audio in) what I do? can I connect player out to c1 directly?
    with tanks Naser Khiavi

    • Seetharaman
      February 5, 2014

      Remove R1 and C1 and feed direct to C2 and common. Adjust MP3 volume for clear sound from the FM monitoring receiver.

  • ibad
    November 2, 2013

    hi,, can anybody tell me how can i tune it?

  • Rex
    September 11, 2013

    Seetharaman, I want to add crystal to the circuit to make it stable.. Where will i connect the crystal.

  • aiya
    July 27, 2013

    is c1 elctrolitic? cn I have c6 fixed? well that would mean the frequency to be fixed too right?

    please reply asap

  • Azeem
    May 5, 2013

    Is 0.022j the same as 0.022pf.
    Can 0.022j replace c7

    • Seetharaman
      May 7, 2013

      Hi Azeem 0.022J is 22nF (0.022uF) 250 volts capacitor. C7 should be 2.2pF.

      • May 12, 2013

        can 2.5pf replace c7?

        • Seetharaman
          May 12, 2013

          Hi Azeem yes. you can use

          • May 15, 2013

            i’ve implemented the circuit. But i’m having problems with the frequency of transmission. It is probably the inductor that i didn’t get well. Please can you explain the oscillator stage of the circuit for me. Also is c7 and that 5pf part of the tank circuit?

          • May 16, 2013

            i got the frequency. However it does not transmit voice signals. If i tap the mic, i can hear it. Also At different frequencies by varying c6. But if i speak, i don’t hear it. If i play mp3, i don’t here it also. I used a condenser electret mic. Please help me. I’ve already submited the proposal for this project in school. I can’t drop it.

          • Seetharaman
            May 16, 2013

            Hi Azeem check polarity of capcitor C2 and try by reducing C4 to .002uF.(2k2 pf or 2200pF) it should solve the problem.

          • May 16, 2013

            i’ve done so, it is still not working. How can i measure inductance. May be its the inductor

          • Seetharaman
            May 17, 2013

            In the notes the winding details of L1 is given you try it it should solve your problem.

  • shameed baig
    April 23, 2013

    dear sir/madam.
    I am shameed baig. I want a FM transmitter ready made kit.
    cell 9886218503

  • ketan
    February 2, 2013

    and sir, how to choose alternate values for variable capacator n inductor?? please reply asap…..

  • ketan
    February 2, 2013

    i dont understand how will signal be amplified if R2=R3. Also, aint 0.022pF too low??

  • DavidCheng
    January 22, 2013

    Will the circuit work if I change C7 to some other value (i.e. 2.2pF or 22pF)? I probably won’t be able to get 0.022pF capacitor

  • Amit Sharma
    January 12, 2013

    Sir
    Medium power FM transmitter circuit

    in which shop available in mumbai
    because i want to the buy. this circuits

  • Chintan
    August 28, 2012

    i am unable to see any oscillations on the collector of Q2.
    What can be the reason?
    I have not connected microphone yet.

  • supath mohile
    August 1, 2012

    please can u describe that on which frequency this medium power FM transmitter circuit will be work.???

    • Abrham
      February 1, 2013

      Please can you describe that on which frequency this medium power FM transmitter circuit will be work.??????????

  • fatunmbi olalekan
    May 6, 2012

    How to generate voltage through water

  • NO name
    April 9, 2012

    i think all ground are connected.,correct??
    but i confuse what is the voltage of ceramic cap. it is 50V??
    and electrolytic cap is 16V??

  • ashnuka
    April 9, 2012

    Thank You.

  • seetharaman
    April 9, 2012

    Hi Ashnuka place order through net and get it or please drop the project, without ceramic capacitors it will not work.

  • ashnuka
    April 9, 2012

    What are the replacements of the ceramic capacitors?I cannot find any of them.

  • February 19, 2012

    can any 1 sedd me full theory n diagrme on my email mrose2929@ymail.com

  • munna
    February 3, 2012

    I understand everything of this diagram except capacitors. I don’t understand which volt of capacitor i’ll use….?

  • seetharaman
    September 19, 2011

    Hi Alex it electret condenser microphone.(M1 is Microphone1)

  • Alex
    September 18, 2011

    Hello, I understand everything on the schematic except for “M1”. Can anyone tell me what component this represents?

    Thanks.

  • ramesh majhi
    September 4, 2011

    hi i am tired in adjusting inductor sometimes it work and sometimes it is out of work what to do?

  • tang
    August 5, 2011

    hi i tried to simulate the ckt in multisim 11 in the op i got voltage of nanovolt it s correct??????
    and also i want a formula for calculating the frequency

  • ResR
    July 13, 2011

    I want to ask is the 0,022pF correct value? I can’t find any capacitor with that value available in Estonia.

  • seetharaman
    July 5, 2011

    Hi Prudhvi you can use anything between 18 to 22SWG super enameled copper wire. Q1 is the mic amplifier and modulator. Q2 is the oscillator and power amplifier.

  • prudhvi
    July 4, 2011

    complete discription about this circuit………..plz send me…..its urgent plzzzzzzzzzz……….

  • prudhvi
    July 4, 2011

    can u give me the gaze value for 0.156uhenry inductor?????
    it is very urgent plzzzzzzzzzz………..

  • complet description
    May 27, 2011

    plz send me the complet theory of this project as soon as you

  • ADN
    April 9, 2011

    hey guys I construct the circuit but i want to now the frequency at the output to receive the signal!!
    please reply as soon as possible

  • ahmad
    March 21, 2011

    iwant jammung circuit with range frequency (800Mhz_2000Mhz)

  • Seetharaman
    March 10, 2011

    Hi Techno girl it is a standard electret-condenser mic with 2pins and of 10mm dia.

  • March 10, 2011

    Please giv me the specifications of the the device M1 used in this ckt… I wnt it as early as possible.

  • Aravind
    February 12, 2011

    what is the frequency range of this circuit

  • Rickson
    January 31, 2011

    That bit above that said:

    1uF = 1000000F
    1nF = 1000000000F

    is wrong.

    1 uF is 0.000 001 Farads
    1 nF is 0.000 000 001 Farads.

    A Farad is a very large unit of Capacitance

  • pokemon
    January 5, 2011

    i think TUNJI’S the best

  • ammir
    November 24, 2010

    i want a diagram with full theory detail and making process and working process

  • seetharaman
    September 1, 2010

    Hi Pecanins any standard FM radio will receive the signal. Tune to a frequency where there is no broadcast signal, adjust capacitor C6 till you get the acoustic feed back through mic. now your transmitter is ready.

  • Pecanins
    August 31, 2010

    will an ordinary FM radio recieve the signal from this circuit?

  • seetharaman
    July 27, 2010

    Hi Saad the best receiver with 1watt audio output to speaker operation from 2 to 12 volt DC is sony CXA1619

  • seetharaman
    July 27, 2010

    yes telescopic antenna can be used dimension = wavelength / 4 (wavelength in metres = 300000 / frequency)

  • linta
    July 26, 2010

    plz replay quickly………..

  • linta
    July 26, 2010

    what are the dimensions of antenna and can telescopic antenna be used

  • saad
    July 26, 2010

    hello sir i want the the circuit for the receiver of the above circuit and want to know the operating range.and also how could i increase it.thanks

  • ramesh
    June 3, 2010

    thanks. with this i colpleted my project.

  • nicks
    April 12, 2010

    how to calculate the value of of the component match by antenna ?

  • MOHAMMAD
    April 1, 2010

    Thanks a lot JOHN it’s worked very well with me.

  • seetharaman
    March 20, 2010

    Hi writting in 3 digit is similar to color code. Brown black brown is 101 That is 10 X 10¹ 100PF, Brown-green-brown that is 15 X 10¹ 150PF, brown black orange 103, 10 X 10³ 10000PF or 10nF or 0.01µF. First two digits are indicated in then the third digit is the mutiplier. You can represent only preferred E12 values in decade series 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82. 159PF is not possible in 3 digit system.

  • March 19, 2010

    Please Engr.help me to convert 10pf,20pf,3pf &159pf to the form of 3-digits number.EG 100,101 etc

  • March 18, 2010

    Please I found it difficult to find capacitors in picofarad instead am asked to convert.But the converted ones are written in 102,104c etc enlighten me on the conversion

    • admin
      March 18, 2010

      Reply to Akinyele Augustine Sola

      104 is 0.1uF
      103 is 0.01uF
      102 is 0.001uF

  • badr-ess
    December 10, 2009

    can you tell me please about the capacitors? is it o.047MIC 47NF ? and what’s value of 0.5MIC ;0.2MIC and (on nano farad nF) and the value of 0.022PF. thanks a lot

    • admin
      December 10, 2009

      1uF = 1000000F
      1nF = 1000000000F

  • Ajimakin Tunji
    October 17, 2009

    Nice one, really worked for my science project. Thanks a lot.

  • Akinjolire Gbenga
    October 17, 2009

    please, where should the negative terminal of the 9v dc be attached.

  • Ajimakin Tunji
    October 17, 2009

    Nice one, really worked for my project. Thanks a lot.

  • August 10, 2009

    plz send me more samples.

    • admin
      August 10, 2009

      ok

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