Long Range FM Transmitter

jacky March 27, 2012 125 Comments

How to make a long range FM transmitter at low cost

Description

The use of transmitters which have a more powerful output than the ‘flea-power’ are sometimes required when there are many obstacles in the path of the surveillance transmitter and monitoring station receiver, or the distance between them is too far so as to make a low powered device feasible. Whereas a typical micro transmitter will produce an RF power in the order of just a few milliwatts, i.e. a few thousandths of a watt, the VHF-FM transmitter described has a power output of between around a half and 2 watts, depending on the power source, which may be anywhere between 6 volts and 30 volts d.c. The battery or batteries should be of the alkaline high power type, since the current drain will be found to be relatively higher when compared to microtransmitter current drain. The power output of this device is somewhat proportional to the current drain and so therefore both may be decreased by altering the value of R6 to a higher resistance, or a variable resistor with a value of around 1k may be introduced in series with the existing R6, so as to give a variable power output. The variable resistormust not be a wirewound device because this would act as an inductor which will cause feedback problems.The audio input to the power oscillator, which incidentally is formed by TR2 and associated components, is derived from a piezoelectric microphone which drives the simple audio frequency amplifier TR1. The input of the audio amplifier is controlled by the gain pot R1, which selects the correct amount of voltage that is generated by the piezoelectric microphone, then connects this signal to the base of audio amplifier TR1 via C7. It may be found that there is insufficient housing space for a bulky piezoelectric microphone, so with a slight modification to the circuit, it is possible to employ an electret microphone insert as shown. Since the RF field that is generated by this transmitter is relatively large, the problem of RF feedback may very well be encountered. This may be overcome by placing the transmitter inside a metal enclosure, keeping all internal wiring as short as possible and the aerial wire.

Component listing for 1 watt transmitter

Resistors Semiconductors R1 = 27k TR1 = BC547 R2 = 330k TR2 = 2N2219 fitted with heat sink R3 = 5k6 MIC = piezoelectric microphone R4, 5 = 10k R6 = 100R

L = 6 turns 22 gauge enameled wire wound on 3⁄16″ former

Capacitors

C1, 2, 3 = 330 pF C4 = 2–10 pF trimmer C5 = 4p7 C6 = 1 nF

C7,C8 = 40uF/25V Electrolytic

Circuit diagram for Long range FM Transmitter

Long range fm transmitter circuitWe have some other Radio Transmitter circuits of your interest;listed below:

1. 2 KM FM Transmitter

2.  200M FM Transmitter

3. Medium Power FM Transmitter

4. Versatile FM Transmitter

5. FM Adapter Circuit for Car Stereo

Comments
  • naresh
    July 14, 2015

    how many km works these circuit pls reply frnds

  • Jay Jongko
    March 21, 2015

    The piezoelectric mic needs a supply voltage to operate. In this circuit, in my opinion, we need to add a resistor connected from the + of mic to the 12volts supply in order to complete the entire operation.
    Btw, thanks for this useful circuit. and indeed, I used it as a reference for my own project.

  • JAmes white
    March 9, 2015

    Thanks for the circuit diagram. The transistor use in the diagram like 2219 is not in my country how can I get some from you.pls reply me as soon as possible I needs your friendship. Thanks I am from Liberia west Africa.

    • Jay Jongko
      March 21, 2015

      Try to look for a CS9013 transistor.

  • freedom
    January 15, 2015

    330pf capacitors how much there voltage

  • Harsh Verma
    December 24, 2014

    Use 2n3904 transistor in place of TR1 and remove r1 and place + terminal of mic to the base of TR1 and also use 100 pf variable capacitor to get clear sound. And also you can use bly81 or blx65 in place of TR2.

  • semixH2s04
    September 7, 2014

    Nice work like,how many feet of antenna can be use to give up to 2km range.

  • Daudi Sulemaani
    April 13, 2014

    Teacher, radio propagation principle says – if electricity is vibrated in a wire at 10kHz and above, those Radio Waves created will are continuous and will be picked even behind hills, why then FM follow line-of-sight yet MW,SW,LW won’t? Thank you. From Ugamda.

  • March 31, 2014

    Teacher, why FM receiver will not receive faraway stations as AM does yet FM transmitter vibrates at more than 100mhz? From Uganda East Africa

    • Seetharaman
      March 31, 2014

      High RF frequencies travel in straight line. to receive the signal line of sight is important. since earth is curved during favorable conditions it can reach 60 to 150kms depends on power and height of transmitting and receiving antenna. AM signals in MW band are transmitted through ground wave hence they can reach longer distance During nights they can travel 1000s of kms. you may get lots of distant stations during nights in your MW AM radio.

  • March 24, 2014

    Sir this ckt making or redimed where are avilable in market and how many ruppies

  • Hasan
    October 18, 2013

    I have already made it. But it’s sound quality is very poor. so much noise………

  • Rex
    September 11, 2013

    Seetharaman I want to add a crystal to the circuit to make the frequency stable. Where can i connect the crystal

  • khali
    August 3, 2013

    R1 -27k , is that pot?

    • khali
      August 3, 2013

      what is c5 value? is that 4.7 pf?

  • Albert
    July 2, 2013

    I have a question that at which frequency i should tune my radio to hear from it tell me please i want to use my small mobile radio to hear that it is working.

  • Rajib saha
    April 9, 2013

    Have you solved Mr. Avdi?
    This is a feedback capacitor which has been connected between Emitter to collector to keep oscillating the tank circuit (Coil and Capacitor). You can use any disk capacitor between 4.7pf to 10 pf as a feed back capacitor.
    You are Lucky because you are from Texas, you can buy BH1417 stereo FM IC and 7.68 crystal to make very very perfect radio. It is very simple. But I am far from America or Europe, so I never found this IC and crystal.
    Regards

  • ALITUHA PATRICK
    March 25, 2013

    TRY TO SEND ME ATLEAST DIAGRAMS OF 300WATTS AND ABOVE; SIMPLIFIED,AND EASY TO BUILD THANKS AND MORE ESPECIALLY RF CONTROL SECTION[RF PRE-AMPLIFIER SECHMATIC DIAGRAM]AND THEN MAIN OUTPUT SECTION

  • ANDYmax
    March 4, 2013

    can any one tell me at what frequency does the above transmitter transmits the data….???

  • barathi
    February 19, 2013

    sir, i want the clear explanation of signal transmission in communication oriented circuits. and i am waiting your favorable replay . thanking you

  • oduns
    February 13, 2013

    @ Seetharaman pls i need a small radio station because my boss told me to let him know when am set so he can get me a licence.
    odunlamisamson@rocketmail.com

  • arp ridwan
    January 2, 2013

    resistance have two pole.
    How can i connect resistance R1…?
    please reply to me….

    • Hasan
      October 18, 2013

      use Variable resistor

  • Raj
    September 3, 2012

    Have you solved Mr. Avdi?
    This is a feedback capacitor which has been connected between Emitter to collector to keep oscillating the tank circuit (Coil and Capacitor). You can use any disk capacitor between 4.7pf to 10 pf as a feed back capacitor.
    You are Lucky because you are from Texas, you can buy BH1417 stereo FM IC and 7.68 crystal to make very very perfect radio. It is very simple. But I am far from America or Europe, so I never found this IC and crystal.
    Regards

  • August 14, 2012

    wery good transmitter

  • Dude
    July 27, 2012

    Hey…. C4 = 2–10 pF trimmer, is not available any alternate?

  • munna
    July 8, 2012

    i need a 10 kilometer range fm transmitter circuit diagram. if it remains to anybody please send me that.
    my email: imtiaz2580@yahoo.com

    i’ll always greatful to you.

  • May 5, 2012

    YOU CAN ALSO VISIT THIS SITE FOR MORE HELP http://kpkpkalpesh.blogspot.in/2011/12/fm-radio-transmitter.html . it will definitely help you 🙂

  • KALPESH CHHABHAIYA
    April 6, 2012

    HELLO FRIENDS,
    I MAID THIS PROJECT SUCCESSFULLY. WITH PROPER FREQUENCY AND STRENGTH.IF YOU WANT HELP THEN CONTACT ME ON kpkpkalpesh@gmail.com or at 08866792042…… i will surly help you to bring out you from the problem 🙂

    • Mohammed se'ad
      September 12, 2012

      I want to make 3 to 5km transmitter how can it be ? I need ful info … Plc replay on my email “mohasead@gmail.com

  • hellen
    March 21, 2012

    is it in the commercial band (88-108mhz)? how i have to make the coil?

  • david
    March 20, 2012

    how many range does it make?

  • Munib Ali
    March 13, 2012

    I am student Of Electrical Engineering Sir Tell me About Which Antena I used This transmitter and
    2nd tell me About Its Case

  • November 28, 2011

    How many cost it takes to make it complete?
    What do you mean by 6 turns 22 gauge enameled wire wound on 3⁄16″ former?

  • gaurav tomar
    November 19, 2011

    sir, i am a student of electronics and communication engg. i want to established a low power 1-2 km. fm transmission station in my college campus. I am authorized by my faculty to working on this project. they will arrange for license of Fm. so please give me appropriate guideline for this through mail @ grvt@live.com

  • seetharaman
    November 16, 2011

    Hi Raja use it through the USB port available on your Laptop.

  • RAJA AMIR
    November 16, 2011

    i want to use externel cd rom with laptop. can u tell me about this.

  • Fitsum
    November 13, 2011

    I need fm transmitter am from Ethiopia and want to transmitte some info to my vilag farmers. I have been trying to mack fm transmitter befor two times i fell to mack it real
    If you have 100% workig project, you can mack my Drem true.
    Send me at city35@yahoo.com

  • rizwan
    November 4, 2011

    can anyone please let me what should be the inductance of L thanks

  • ali maqsood
    October 24, 2011

    can anyone plz tell me what type of oscillator is this thanks

  • ABD-UR-RHMAN
    September 7, 2011

    SIR,I AM A STUDENT,I NEED A CIRCUIT OF CRYSTAL CONTROLLED STEREO FM TRANSMITTER. I HOPE YOU WILL HELP ME.

  • seetharaman
    August 15, 2011

    Hi Simon you can use 1/2 wave length dipole for directional radiation and for omni-directional radiation 1/4 wave length whip antenna (telescopic antenna of suitable length can be used)

  • simon
    August 14, 2011

    how long must be the antena?

  • ziddik
    August 2, 2011

    hi jack, my mail id is ziddique007@gmail.com..

  • THIYAGARAJAN
    July 31, 2011

    hi everybody,
    I need the steps to make my own fm transmitter so
    if intrested means someone can help me

  • Jack
    July 2, 2011

    Hi ZIDDIK… I want your circuit.. Your mail id please…

  • pujan
    June 26, 2011

    It’s really great experience to work on above fm trasmitter circuit diagram. it’s having quite good frequency range…..

  • April 28, 2011

    C8 listed after C3 SHOULD NOT be their
    The correct C8 is listed after C7

    C5 can also be a: 47pF
    C6 can also be a: 0.001uF

    R1 27k– is that correct?

    TR1 can be substituted with a 2N3904

    L – a 3/16″ drill bit will work fine for this

  • Alone
    April 19, 2011

    Hi Master
    I need a 10km range fm 88-108 mhz transmitter please send me some detail or much better if you can provide the circuit diagram and the component list please just mail it to me at kmuin@yahoo.com thanks and more power.

    From Alone
    Johore Bahru Malaysia

  • ziddik
    March 29, 2011

    did anyone try this circuit? I want build it and also i have build a 100 meter range transmitter with only one bc547 transistor n it works perfectly with high clarity sound output!! If any1 want the diagram just mail me

    FROM ZIDDIK

    TIRUR,MALAPPURAM DT,KERALA-INDIA

  • santu ghosh
    March 23, 2011

    please provide me 10 km range fm 88 – 108 mhz.fm transmitter…send details-santu3090@gmail.com

  • Programming
    March 11, 2011

    Hi there, You’ve done an excellent job. I’ll certainly digg it and personally suggest to my friends. I am confident they will be benefited from this web site.

  • Krishna
    January 19, 2011

    Hi, I am looking for a 15v 1.5Amph smps circuit diagram and googled a lot and end-up with nothing. If any kind heart can help me on this, i will be very much thankful. Thank you verymuch in advance..

  • soranakoyan
    January 17, 2011

    bu nasıl devre la aq.

  • Vaseem Mehran cp
    January 10, 2011

    Nice circuit.its worked very well.
    Thankyou

  • Seetharaman
    November 29, 2010

    Hi Avdi use 2nos 10pf in series to achieve 5 pf which is ok for C5.

  • Avdi
    November 29, 2010

    HI i buy 2 FMtransmitter kit 1[KIT32] and 1[K18V2] but after i insatal all parts on bord , nothing no workin i install parts on bord 100% good,,but i think maybe they sale wrong parst or damaged alectronickit,now i m buildin one nother with 2Transistor2N2222,,,but i can t find ceramic disc 4p7,,so can sameone help me,,what i can use inplace 4p7, i have ceramic disc 5,i have 10,,i have 18,27,33,68.102,103Z,104Z.. but 4p7 no have no wher stores,,frys electric radishack no have,,, I M FROM TEXAS USA

  • Daniel Akan
    November 22, 2010

    i want to to program a micro controller to work on the traffic light can you help me

  • September 26, 2010

    can we extend the range by using a diple antenna

  • September 26, 2010

    can we extend the range by using a dipole antenna

  • Sumeet
    September 25, 2010

    Can you tell me if there any circuit for generating Train Horn like sound and which can be implemented on My Bike.
    Input Voltage Supply Should be 12VDC.
    Thank You.

  • Seetharaman
    September 18, 2010

    Hi Sanjay this transmitter itself can be used with dipole antenna to achieve 2kms.
    Hi Ravi what is the frequency of operation you require, AM or FM omni or uni directional.

  • ravi ranjan
    September 6, 2010

    hiii……
    i m a btech 3rd year electronics and communication engineering student..
    i want to make a radio station at our college for our tech fest only..
    will u elp me with the circuit by sending it 2 me…
    i need a transmitter of nearly 2km range..

    thanks..
    waiting 4 your prompt reply..

  • Sanjay
    September 3, 2010

    Hy,i am sanjay please inform me about 2km long rang but easy circuit of fm transmiter. Please mail me.

  • favor
    May 25, 2010

    hi, i want to make a transmitter project for educational purpose. can you please help on this? please email me the circuit and detail at favor4prince@yahoo.com

  • seetharaman
    May 19, 2010

    With a whip antenna of wave length / 4 you can cover minimum 1/2 km distance.

  • seetharaman
    May 19, 2010

    Hi Favas you can tune this transmitter in frequency range of Band I, Band II and Band III (between 50 to 250MHz)

  • May 19, 2010

    well dude how long it can transmit ???

  • April 26, 2010

    Thanks for the circuit. I will try it.

  • seetharaman
    March 29, 2010

    Hi Favas sorry for this long silence. this transmitter will operate in VHF say 65 to 200MHz. Since we have with us broadcast band receivers operating from 88 to 108MHz. we can use them to monitor by tuning our transmitter to this frequecy range.

  • gurtaj
    March 2, 2010

    hey hi…i want to make a transmitter receiver project for educational use.can you please help me on this.please email me the circuit and detail at gurtajs4@gmail.com

  • favas
    February 26, 2010

    whats its Frequency.. ? thanks..

  • Seetharaman
    February 18, 2010

    Mr. Kulla you make a small variable trimmer yourself. Take 0.2mm insulated wire 2″ length each. connect one to one end of the coil and the other to other end of the coil. now twist them closely tightly (like twin twisted plastic wire-not electrically connecting them). Now you can expand compress the coil ‘L’ to acheive the required frequency.

  • KILLUA
    February 15, 2010

    i see… thank you so much.! this really helps… can i ask another question? can i substitute the trimmer capacitor with another kind of capacitor (as in electrolytic or mylar).. the local electonics stores here dont have trimmers..

  • kiLLua
    February 10, 2010

    you can contact me at freezingflame_christ@yahoo.com
    it’s also my email ad for facebook..

  • kiLLua
    February 10, 2010

    hi.. i hope the admin would read my comment.. im a neophyte when it comes to electronic circuits, but i just want to ask this question. the r1, which is 27kohms, has only two ends right? so why it is that there are three components connected to it? 2nd question, what does a piezoelectric microphone do? piezoelectric means electricity by means of putting pressure on a thing..

    pls answer me, i need to be guided.. thanks.

    • admin
      February 10, 2010

      reply to kiLLua
      R1 is a potentiometer and it has three terminals (two end terminals and a wiper terminal).

      Piezoelectric microphone will produce an output voltage according to the sound waves falling on it. It converts the vibrations caused by the sound waves into a proportional electrical signal.

  • mukba
    February 3, 2010

    if anybody needs help,add me in skype:mukba16 or in nimbuzz:nika92
    i am constructor and i have tested this schems…

  • NILOY
    February 2, 2010

    Hi i’m a daily reader of circuits today, and i’m in love with ur site, many many thanks for ur hard work and for such wonderful and useful circuits

    But anyone tried this circuit and is it a success?

  • January 22, 2010

    I NEED A CIRCUIT DIAGRAM OF A LOW COST WALKIE TALKIE.

  • January 12, 2010

    Yes it is a good FM transmitter, 2N2219 is a RF transistor and I saw it in many high power FM transmitters.

  • January 11, 2010

    fm transmitter circuit ;plz give me the distance to transmit and make the circuit……plz reply……thanks.send reply ……

    • admin
      January 11, 2010

      This circuit has a range of about 1.5Km at full supply voltage.

  • jeya kumar
    January 11, 2010

    how much distance i can transmit .its frequency range

  • toni
    January 3, 2010

    can i have the reply asap.., plz,.,., i need it to make my project,.,.,tnx,.,.,.

  • toni
    December 28, 2009

    wat typ of antenna should we use for this circuit and how long should it be????

  • kingsley joseph
    December 15, 2009

    send this t; my mail box.

  • Manoj kumar
    November 19, 2009

    Hi there,i am a daily reader of your site,circuitstoday.I just want to know,what is the distance covered by using the above LONG RANGE FM TRANSMITTER.Plz reply me or better mail me!Thanking you.

    • admin
      December 10, 2009

      At full supply voltage it will cover up to around 2Km. For maximum performance you need a good power supply , matching antenna, correct inductors and a very efficient PCB.

  • Sm Rafiq
    November 12, 2009

    i need ac motor drive circuit diagrams

    • admin
      November 13, 2009

      pls tell me your specific application

  • September 24, 2009

    sir can you please make a buffer amplifier???

  • jdtrada
    September 18, 2009

    i need a circuit for fm transmitar.

  • APPIAH FRANK
    July 23, 2009

    HI MASTER I NEED A TV TRANSMETER CIRCUIT

  • Suraj Prem
    June 20, 2009

    Will it help in increasing FM range inside the house.

    • admin
      July 9, 2009

      This transmitter is powerful enough to be used in a house.

  • June 17, 2009

    i need 100Meter range FM transmitter cct. diagram

    • admin
      June 18, 2009

      you can expect one son

  • June 17, 2009

    i want a 20v transistor transmeter

    • admin
      June 18, 2009

      i will add one soon

  • manu
    May 27, 2009

    hi good job!!!! it will help to make projects

  • michael
    April 27, 2009

    what is the transmitting range

    • admin
      April 28, 2009

      around 500m

  • April 22, 2009

    i need 100Meter range FM transmitter cct. diagram.

    • admin
      April 24, 2009

      a lot of FM transmitter circuits are here.Pls look in the radio circuits category.

  • mensah
    April 22, 2009

    Hi Master i need an FM transmitter cct. diagram to cover the range of about 1000 meters in my village.

  • fagh
    April 21, 2009

    Ineed a fm radio schematic without any IC. thank you from fagh

  • April 20, 2009

    thujiya aii la zhavla phandra hattii with 12 bulli

  • April 19, 2009

    Please can the circuit diagram of a 200W power transmitter and a 5KVA UPS be sent to my e mail box. which is geracotin2000@yahoo.co.uk.

    • admin
      April 19, 2009

      i am working on it

  • April 2, 2009

    can a variable capacitor be use for trimmers?

    • admin
      April 5, 2009

      i think trimmer is a better is option.

  • March 22, 2009

    I live in Myanmar.The transmisson licenses aren’t tight here.I want a FM Transmitter with a
    wattage of up to 4-watts to transmitter as an
    amateur.Could you help with this?Thanks!

  • March 22, 2009

    I live in Myanmsr.The transmisson licenses aren’t tight here.I want a FM Transmitter with a
    wattage of up to 4-watts to transmitter as an
    amateur.Could you help with this.Thanks!

  • February 8, 2009

    what is the range of this transmitter?thanks

  • January 17, 2009

    I have been looking for thisd info thanks!!

  • January 2, 2009

    ALL ARE VERY GOOD,THANK YOU,
    GOD BLESS US

    FROM,
    CHEMMAD,MALAPPURAM,KERALA,INDIA.

  • Jason
    November 21, 2008

    What is the range of this transmitter? Thanks..

  • sunny
    June 27, 2008

    Sunny : What should be the value of C7 and C8?
    I think they are disconnected terminals ,right?

    Author:Thanks for pointing the error.I have added the values of C7&C8 in the parts list.Please check.

  • khasru
    May 31, 2008

    how much distance i can transmit .it’s frequency range

  • khasru
    May 31, 2008

    Khasru:can i use it for radio transmission.

    Reply: You are from India.I figured that from your name.Sorry my friend,you can’t use it for radio transmission. Any sort of radio transmission without proper licence is punishable in India and of course in most of the countries.For educational or study purpose you can make radio transmitters,thats quite OK.But continuous transmission over long ranges will invite trouble.If police came to pick up your transmission in their wireless or any body files a complaint against you ,that will be trouble.If you are regularly transmitting,they can easily track the source.

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