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  • This is very stable, harmonic free, long range fm transmitter circuit which can be used for fm frequencies between 88 and 108 MHz. This can cover 5km range (long distance). It has a very stable oscillator because you use LM7809 stabilizer which is a 9V stabilized power supply for T1 transistor and for frequency adjustment that can be achieved by using the 10K linear potentiometer. The output power of this long range rf transmitter is around 1W but can be higher if you use transistors like KT920A, BLX65, BLY81, 2N3553, 2SC1970, 2SC1971…

    T1 is used as an oscillator stage to deliver a low power stable frequency. To adjust the freq. use the 10k linear potentiometer like this: if you trim down, towards ground, the freq. will drop and if you adjust it toward + it will rise. Basically the potentiometer is used as a variable power supply for the two BB139 varicap diodes. Those two diodes act like a variable capacitor when you adjust the pot. By varying the diode capacitance the L1 + diodes circuit makes a resonance circuit for T1. You can use transistors like BF199, BF214 but do not use BCs. At this moment you don’t have yet the long range fm transmitter because the power is quite low, no more than 0.5 mW.

    How does long range fm transmitter works

    Make sure to encase the oscillator stage in a metallic shield to prevent parasite frequencies destabilizing the oscillating stage.

    T2 and T3 works as a buffer stage, T2 as a voltage amplifier and T3 as a current amp. This buffer stage is very important for freq stabilization because is a tampon circuit between the oscillator and the preamp and final amplifier. It is well known that poor transmitter designs tend to modify freq. as you adjust the final stage. With this T2, T3 stage this won’t happen anymore!

    T4 is a preamplifier for the fm transmitter and is used as a voltage power rf amplifier and will deliver enough power to the final T5 transistor. As you can see T4 has a capacitor trimmer in its collector, this is used to make a resonance circuit that will force T4 to amplify better and get rid of those unwanted harmonics. L2 and L3 coils must be at 90 degrees angle one to another, this is to avoid frequency and parasite coupling.

    The final stage of the long range rf transmitter is equiped with any rf power transistor that has at least 1 watt output power. Use transistors like 2N3866, 2N4427, 2N3553, BLX65, KT920A, 2N3375, BLY81, 2SC1970 or 2SC1971 if you want to have a pro fm transmitter with enough power to cover a long range area. If you use 2N2219 you will get no more than 400mW. Use a good heatsink for the T5 transistor as it gets a little hot. Use a good 12V/1Amp minimum stabilized power supply.

    Long range fm transmitter circuit diagram

    long range fm transmitter

    click on the schematic image for larger view

    T1 = T2 = T3 = T4 = BF199
    T5 = 2N3866, 2N4427 or 2SC1970 for 1Watt / 2SC1971, BLX65, BLY81, KT920A or 2N3553 for 1.5 to 2W power.
    L1 = 5 turns / 0.6mm / 4mm silvered copper
    L2 = 6 turns / 0.8mm / 6mm enamelled copper
    L3 = 3 turns / 1mm / 7mm silvered copper
    L4 = 6 turns / 1mm / 6mm enamelled copper
    L5 = 4 turns / 1mm / 7mm silvered copper

    Use silvered copper for L3 and L5 if you want to obtain better characteristics.

    Adjustments of the long range transmitter

    Start by construction the oscillator stage, solder a small wire to T1 10pF capacitor out and listening to a fm receiver, trim the 10k pot untill you can “hear” a blank noise or if you plug in an audio source you can hear the music. With a 70cm wire you can cover a 2 – 3 meter area just with the oscillator stage.

    Then continue to build the rest of the rf transmitter, use proper shielding as indicated in the circuit schematic. When you finished the transmitter construction connect the antena or better a 50 or 75 Ω resistive load and use this rf probe, you can use 1N4148 diode instead of the probe diode.

    Adjust again the 10k pot to desired freq. and then go to T4 stage and trim the first collector trimmer for maximum voltage indication on the multimeter. Then continue with the next trimmer and so on. Then go back to the first trimmer and readjust again untill you obtain the highest voltage on the multimeter. For 1 watt rf power you can measure a 12 to 16 Voltage. The formula is P (in watt) is equal to U2 / Z, where Z is 150 for 75Ω resistor or 100 for 50Ω resistor, but you must remember that the real rf power is lower.

    After those adjustment, if everything is going well connect the antenna, continue using the rf probe, readjust again all the trimmers starting from T3. Make sure you don’t have harmonics, check your TV and radio set to see if there is disturbance on the band. Check this in another room, far away from the fm transmitter or antenna.

    That’s all folks :D … This is my design for a long range transmiter and is working well. I used 2SC1971 which has a 12dB power gain in 88 … 108 MHz band, this is around 15 times rf amplification. As T4 delivers around 80 to 100 mW of rf power the final stage has enough power to deliver between 1 to 2W depending the transistor usage.

    
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    151 Responses to "Long Range FM Transmitter"

    1. plse can u send me fresh circuit diagram for long range fm transmitter…..

    2. m.raghib malik says: on July 3, 2009 at 7:48 am

      I HAVE REQUIRED LONG RANGE AUDIO/VIDEO TRANSMITTER /RECEIVER.IF ANY ONE HAVE….. PLEASE SEND ME

    3. m.raghib malik says: on July 3, 2009 at 7:50 am

      ANY 1 HAVE HI FI STEREO AMP CIRCUIT DIAGRAM????

    4. Achyuta says: on July 27, 2009 at 12:31 pm

      please send me long range fm transmitter operated at voltage 9v

      • How can I operate this circuit at 9 volts?If the same circuit is operated at 9 volts will it result in shortening of its range?If I want the same range & want to operate at 9 volts,what modifications are necessary?

      • Pls hw can i increase a transmitter range from 20m to 800m.u can send the reply to my email add. Thanks

    5. I need mini FM Transmiter

    6. plz give me a coffee for opening my eyes and view the circuit ;)

    7. this is very hard to build very bad

    8. Can somebody help me to get a Long range FM Transmitter circuit Diagram to cover arround 20 Klilimeters or more than that. This is to a College to do a FM for Students Programe. If any once could I thank them. If any one know Plesae mail me mrajaan@yahoo.com

    9. i m live in pakistan .
      i want 2 purchase fm transmeter with in 50 miles.
      anybody hlp me.

      gsmpower@yahoo.com

    10. my Dear pakistanis,

      You must have a lisence for the purchase of a long range FM transmetter. the above circuit have a maximum range of 4 to 5 kilometes.you will not find any long range circuit on the net. So dont depend on “Goraaz” and experiment your own circuits if you want development in electronics in pakistan.
      contact me if u need any help
      03325857287

      • Md. Alvi Al Amin Master Palash says: on June 22, 2010 at 9:43 am

        Please Give me long rang fm warless transmitter, Receiver & Recorder Easy Diagram & Parts JPG Photo Circuit. Im a News Editor. I needed the circuit my profession.

      • bappa dutta says: on February 22, 2011 at 2:29 pm

        dear sir
        i live from krishnagar (w.b) i want one fm transmiter up to6 to 8 km range plz contact me i manufactring 2 to 4 km range transmiter but ineed 8 km range transmiter plz help meee….

      • bappa dutta says: on February 22, 2011 at 2:34 pm

        dear sir
        i live from krishnagar (w.b) i want one fm transmiter up to6 to 8 km range plz contact me i manufactring 2 to 4 km range transmiter but ineed 8 km range transmiter plz help meee….mob-+919153666500,+919614392322

      • ashok doctor says: on August 7, 2011 at 5:19 am

        I need a long range(1w or more)FM transmitter to send switching pulse to the FM receiver.
        Many circuits of FM TX are available but the source is audio,I want it to switch on the equipments in our Amusement park.Please tell me what should I do to make audio type FM tx work to send switching pulse.
        Thanx,
        Ashok

      • Dear,
        u can use the same transmitter with dtmf .u can control up to 16 separate devices with different code of dtmf.
        Thanks
        satheeshvs@yahoo.com

      • u can use rf amp

    11. please, i want to know is the above circuit diagram is working circuit or some component variations needs to be made to make it work?

      • Marius says: on May 22, 2010 at 9:27 pm

        Yes, the long range fm transmitter circuit presented here will work if is build as indicated in the article.

    12. if it is working, send me mail, if not, tell me the variations to be made though this e-mail: all4chuks2@yahoo.co.uk. thanks

    13. Richard Wassw says: on May 25, 2010 at 4:48 pm

      Please i need suport to have a long range fm transmitter of more than 50 killo metters.

      iam a ugandan and need to set up a community radio sation

      please contact me on grandrichards@yahoo.com or call +256-776304051.
      thanks

    14. Richard Wassw says: on May 25, 2010 at 4:53 pm

      dear thomas, do you effectvely use the transmitter? and for what range and what purporse?

      thia is richard from uaganda

      grandrichards@yahoo.com

    15. simple radio transmitter says: on July 3, 2010 at 10:19 am

      I seem to have found this site where the information I need, I appreciate your sharing of information

    16. According to the diagram T5 is an NPN transistor. But, I boutht a 2SC1971 which is a PNP transistor. So I could not make the circuit.

      Please, solve my problem.

    17. Sir,

      L1 = 5 turns / 0.6mm / 4mm silvered copper
      Does this mean

      5 turns on a 0.6mm thick rod of 4mm silvered copper??

      and about the output you have given us two wires are we supposed to use both??

      if am using a radio amplifier does it increase the range[distance covered]??

      what is 1w fm transmitter or 5w fm transmitter? whats the difference between them? does it help in the quality of service provided or the range again?

      Am sorry if these questions are lame but am new to this

      RaGHuL

      • P. Marian ElectroSchematics.com says: on October 20, 2010 at 9:36 am

        That means a 4 mm diameter coil with 5 turns of 0.6 mm thick silvered copper wire.

      • Sir,

        Silvered copper wire isn’t or rare to be found in my place. Can you please suggest the good substitute for this?

        thankQ

    18. I HAVE REQUIRED LONG RANGE AUDIO/VIDEO TRANSMITTER /RECEIVER.IF ANY ONE HAVE….. PLEASE SEND ME

    19. i nead circuit to make 3 4 km fm bug transmitter and articles names also if some body can help me thanks

    20. i want to buy fm transmitter with range 4 or 5 or more km if some one send me in PAKISTAN send me sms on 0092 [0343]6224488 or mail me chandmazhar@yahoo.com Thanks

    21. hello,
      I ant to build a FM transmitter of range 5-8 km for my final year college project ,
      please help me as soon as possible ,my email id is – sintu_004@rediffmail.com

      Thanks in advance.

    22. Sudip UPreti says: on March 11, 2011 at 5:37 pm

      what device is 3-pinn 7809.

    23. dear marian sir. Which is the most powerful rf transistor available in the market which can deliver up to 2 or 3 watts? And does the range of a transmitter depend on turns of coil or rf transistor? Please help me… and sir. is it possible to use the copper wire which is used to wind a transformer? (copper wire inside a transformer)

    24. mansing rai says: on March 12, 2011 at 5:31 pm

      please send me long range fm transmitter operated at voltage 12v about 10k. m transmit.

    25. santu ghosh says: on March 23, 2011 at 10:31 am

      please send me long range fm transmitter operated at voltage 12v about 10k. m transmit.

    26. ANDERSON says: on May 19, 2011 at 11:44 am

      can you help us with the block diagram of your circuit? TY

    27. Dear Friend,
      I appreciate your Long range FM Tx circuit.What type of antenna do you recommend?Also,if I want to send a switching pulse instead of an audio what modifications are required?
      Thanx.

      • You can use a simple dipole or folded one. I do not know if you can send switching pulse with this frequency modulation transmitter. Why do you need this adaptation?

      • I want to remote control certain equipments in the very large farm.I’ve a remote control but it has just 500 m range.your design can solve this problem.But your circuit sends audio.Yes you can use to send switching pulse in FM too.I’ll remove speaker from the radio & use a R-S flip flop circuit with relay to control equipment.Suppose I short the input terminal to ground,momentarily,won’t the click be transmitted?
        I’m going to try any way!I’ll let you know if it works.

      • u can modify wireless doorbell and try to put an rf amp. then at the receiver put a relay… i try that one and i have a schematic….but i don’t know were to post it

      • u can make a large range circuit ashok its simple use mt 8800 chip u can control many things by fm transmitter. rf amp to increase the range on transmitter 1km use low power transister c 2570 150mw with 9v low mah u can gain max power as rf amp .

    28. Dear Marion,
      Thanx for the tip.Actually,my friend has a huge Amusement park & wants to switch on & off certain flashing & warning lights with a remote.I assembled a remote RF switch for him but it has just 100 M range!
      Do you have a PCB pattern for this Tx?

    29. Sir,
      may i know is the microphone requirement for this circuit?

      Besides, may i use the same material to build all the inductors in the design?

      Instead of using BB139 variable-cap, what else of package can i use ?

    30. Aspiring Elecronics Major says: on August 1, 2011 at 3:35 pm

      I don’t get it, if the Transmitter has a frequency of 88 to 108 MHz, how does it have a 5km range? If Wavelength = Speed of light/ frequency, then you should have 300/88 (for max.), which is about 3.4 m, right?
      How do you reach anything more than that?

    31. Jacinaldo Jr. says: on August 7, 2011 at 4:40 am

      Assemble the circuit as described, but that T5 can not work as it should. I’m using the 2SC1971, but the strain on your pickup is only 200mV peak. Can you help me?

    32. m.raghib malik
      July 3, 2009 at 7:48 am

      I HAVE REQUIRED LONG RANGE AUDIO/VIDEO TRANSMITTER /RECEIVER.IF ANY ONE HAVE….. PLEASE SEND ME

    33. please can u send me fresh circuit diagram for long range fm remote control circuit diagram.

    34. Ajin Kumar says: on August 23, 2011 at 2:02 pm

      hi
      I’m just trying to make an Radio transmitter and receiver, I don’t know how to make it as in my frequency range can you help me with some simple and useful diagrams
      my e-mail id is “ajinadimali@hotmail.com

    35. I NEED A FM TRANSMITTER RANGE OF 2 KMS

      PLZ CONTACT ME @ 9486359508

    36. DEAR FRIENDS,
      I NEED A FM TRANSMITTER RANGE OF 1 TO 2 KMS AND I NEED THE CIRCUICT DIAGRAM AND COMPONENTS NAME .

      BASICALLY I AM INTRESTED IN ELECTRONICS BUT I AM COMPUTER RELATED STUDENT SO PLEASE TEACH TO CREATE A FM TRANSMITER OF THE ABOVE RANGE

    37. I just built it today and i have to say this is a brilliant design and walkthrough! Thank you very much =D

    38. MOHIT KUMAR says: on September 16, 2011 at 8:38 pm

      HI FRIEND .I WANT FM TRANSMETER RANGE 10 KM APPROX .IF AVILAVLE PLZ CONTACT ME.+919634552388

    39. can u send a video high range transmiter and reciver

    40. I want to buy a fm transmitter if any one have this please call me on +917809256711

    41. Pls i need micro spy transmitter/reciever schematic of 2km & above that can be power frm 9V or 12V source.

    42. Please i need micro spy transmitter/reciever schematic of 2km & above that can be power frm 9V or 12V source.

    43. please i need a good stable fm transmitter circuit that transmits rf signal at a long range with no/less noise. i need your help please email me. much is appreciated. thank you

    44. suggestion…. to make it stereo try to use stereo encoder and connect the output to the audio input of a transmitter….

    45. Hi, there,
      When I went shopping for the parts for this circuit, BF 199 transistor couldn’t be bought.Is there any transistor to replace it? And two BB 139 variable cap are packed in one parts? Does it look like
      a “transistor” ? I did not found that part, but I found BD 139. Are these two code same and can be used? How does it look like?

      And if you have the “printed circuit picture”(actual size) for this transmitter circuit, please send me,too, along with the answers to my questions above. I hope you’ll help me. I am about to construct this circuit! I’ll be waiting your reply to my email Inbox or right here. Please help me. Yours.
      My Email address is myokoko19(at)gmail.com. Please note, (at)gmail.com is @gmail.com. So much thanks indeed.

    46. sir,
      I want a long range radio transmitter circuit diagram………range should be more than 10 km. I have designed a block diagram for controlling three phase electric motor with rf control….I need that radio that can deliver me an update information about the motor i.e, it’s rpm, temp., amps., and voltage!!!!!! If u please help me then i’ll be highly greatfull to you…..

    47. Please visit to my blog site that contains an FM transmitter and the transmitter SW1 commonly in use for two-way communication with jangakauan far with little use of the component.

    48. please i need 100% working fm transmitter circuit that transmits signal at 1 km range or more. I have been trying to build FM transmitter but wont work. now i need for school project. If build it i will win 800 dollars. I have only 1 week i need your help Am from Ethinga
      email me at city35@yahoo.com
      thank you

    49. Sonny Eugenio says: on November 24, 2011 at 8:17 am

      I had a hard time digging through the long list of mostly unrelated post on this site. Those of you who are asking for circuits go and look somewhere else. All postings should only be related to the circuit and nothing else.

    50. i require 10 km fm transmitter. india

    51. Bamdad Amini says: on November 27, 2011 at 12:31 pm

      i need too rf amps 10waat

    52. I have completed this circuit but the last T5 stage is not working , due to this its only gives the range of about 60 ft not more than that !

      • What kind of transistor have you used for T5? Make sure everything is connected properly!

      • I have used the 2SC1971 transistor which is quiet expensive than other, every thing is fine because i assembled 2 circuits just for walkie talkie purpose but the range is not more than 50 meters maximum because at 45 meters onwards the signal gets distorted and finally at 50m the signal disappear !!

    53. Bamdad Amini says: on December 3, 2011 at 8:59 pm

      Tnx for this help;-)

    54. sent me fresh circuit diagram

    55. i need mp3 with mic fm transmitter circuit diagram

    56. I love construction of circuits but the area i live in, most of this component are difficult to find or not at all. Please, is there away that i can get some from your store? I will be most greatful if you help me out.

    57. abdur rahman says: on January 2, 2012 at 9:43 pm

      sir,
      I want a long range FM radio transmitter circuit diagram………range should be more than 10 km.

    58. abdur rahman says: on January 2, 2012 at 9:49 pm

      hello,
      I want to diagram of build a FM transmitter of range 5-10 km for my project ,
      please help me as soon as possible ,my email id is – rahman8606@gmail.com
      Thanks in advance.

    59. 5KW FM TRANSMITTER FOR SALE IN PAKISTAN
      LIMITED STOCK.
      Contecct no. 03137381394

    60. Noorazam says: on January 8, 2012 at 5:57 am

      I want 5kw transmetr plz 03067951039
      03044477606

    61. I want the circuit diagram of the long range fm transmitter can you send it to me please

    62. dear dr mouhan
      how are you
      I need simple walki talki on 27 mhz circuit pls help me
      thank you
      yasinamini

    63. shahema khan says: on January 20, 2012 at 2:06 pm

      i want complet fm tranmitter 500meter RANGE 9v (Lm7809)POWER SUPPLY WITH MICROPHON

    64. shahema khan says: on January 20, 2012 at 2:08 pm

      i want complet fm tranmitter 500meter RANGE 9v (Lm7809)POWER SUPPLY WITH MICROPHON
      CON=07417371158

    65. Respected sir,
      can i know what is the copper sheild means
      how can we sheild the circuite
      you mean to say with copper plate or any thing else
      please give me a reply
      or send mail to
      “anila35@rocketmail.com”

    66. dear there
      thank you for best circuits
      from iran- yasin amini

    67. Hello ! If somebody can help me i need a 500w fm stereo transmitter circuit diagram.
      I cant bye it becose i dont have a many but i can make it myself. please give me some help . Thanks…

    68. there is no reality in the range of this transmitter. it is waste of time to stick on this circuit. so do not waste your time.

      • Why are you so sure? This long range transmitter was built by me and is working just fine as I mentioned in the article. The range depends on the height of the antenna, the type of coaxial cable and the correct construction of the circuit.

        LE: there was a mistake in the schematic with the 2 capacitors (6 – 40pf) between T4 and T5). The capacitor C2 was placed between T4′s collector and ground, and that was wrong, it should have been after C1.
        Sorry for that.

      • e gual seria a correção desse erro,eu o constri e não foncionou o amplificador final.gostaria que você min orientasse o que eu devo fazer.

      • Hello Marian,

        What are those mistakes? can you please mention it.

        Thank@

      • What are the mistakes and corrections, pls i need ur reply urgently. Or better still send to my mail pls. Thanks

      • The capacitor C2 was placed between T4′s collector and ground, and that was wrong, it should have been after C1.

      • Samrajih says: on May 7, 2012 at 9:27 am

        “…it should have been placed after C1.” what do you mean? Do you mean between the collector and ground or after the emitter? Please elaborate.
        And please, where is the 12v power supply connected? Or does the cct rely on the 9v alone?
        Thanks in advance.

    69. i am radio makanic i have made so many tx shortwave cw am fm defrent range defrent mhz if any has problum he can call me for his help this is my mobile n 03312500542 dilraham@yahoo.com

    70. Can I also have some pics and info like Myo Ko:
      “And if you have the “printed circuit picture”(actual size) for this transmitter circuit, please send me,too, along with the answers to my questions above. I hope you’ll help me. I am about to construct this circuit!”
      Regards,
      Sotos
      email: alexangeorge67@yahoo.gr

    71. hello, I’m hoping someone can help. I’m building a circuit that runs 20-100KHz 200W 20V but i specifically do not want to transmit with it. unfortunately i cant just shield it as it involves an exposed blade shaped loop of wire (84cm long, 48cm out 48cm back). i need to know which variable is responsible for range.
      all other things being equal, does range only relate to voltage and frequency or does current have a meaningful role to play?
      if my circuit is likely to transmit can anyone think of a way of preventing it from doing so?
      thanks,
      lenny.

    72. Pls be specific on where to connect the 12 power supply. And pls i cant get the bb139, can i use a signal diode and capacitor (IN4148 + 20pf) instead? Pls reply, its urgent. Anybody feel like helping, i’l appreciate it.

    73. Nepaliman says: on May 10, 2012 at 2:17 pm

      Hello P. Marian,
      may i use 2n3904 or BF494 instead of BF199?? I am going to make this one. Please reply me. Otherwise i will get frustate cause of failure.

    74. boka chodara tora jibane 10km fm transmitter ar ckt diagrm create korte parbi na amar sange contact korbi

      ph no -9378267797

    75. Kuroro Ruciful says: on May 22, 2012 at 10:03 am

      Hello P.Marian,

      What’s the maximum range of this FM transmitter? Will this be good enough to start your own FM radio station in the neighborhood?

      Would it be possible if you could send me a picture of the finished device and perhaps the PCB layout, if possible?

      Thank you very much.

      Kuroro

      • The maximum range depends on the antenna type, quality and length of the coaxial cable that you use, correct adaptation of the final stage and more. Usually the antenna must be mounted as high as possible for maximum range. If you use it in a town with tall buildings and your antenna is lower than those buildings then the range can be 1 km at 2W, but if your antenna is on the tallest building then the range can be more than 5km at 2W.

      • Kuroro Ruciful says: on May 22, 2012 at 11:10 am

        Thank you for the speedy reply.

        By the way, do you have a picture of the finished device and a PCB layout? Do you also have the corrected version of the schematic diagram? I’ve read on one of the comments that you’ve made a mistake about the placement of the capacitors.

        Thank you very much

      • I do not have any pictures or pcb with it :|
        The schematic was replaced with the good one.

      • THANX SIR

      • Kuroro Ruciful says: on May 30, 2012 at 10:31 pm

        Thank you P. Marian. Will try to work on this.

    76. mohandis says: on June 1, 2012 at 7:22 pm

      this is for audio what about digital transiever?
      I need to make long range digital remote control so what about the receiver?

    77. i want a fresh 7km radio fm transmitter circuit pls.

    78. may I use 18—24 volt power supply only in final stage for 2n3553 in order to increase out put power?

    79. Available: Small DIY FM Transmitters with aerials. Maximum Range : 500 mtrs. Very Cheap. Can be sent by post anywhere in India. send mail to jawedatjaweddotin. thanks

    80. create quality transmitters are very dificult and not allowed. but im very fun.

    81. Hi
      how can use 2n2219 or 2n3866 for driver stage before final stage for more power???can use that to more than 2 watt power?

    82. B.Marian says: on August 2, 2012 at 5:42 pm

      hey I have bf494,bf254,bf214 and bf215 (and 3866 one) transistors.will it go?:D
      app esti roman?

    83. it is good but very critical.

    84. It is really good circuit. But complex.
      Please give easy circuit 4 us.

    85. please send me simple but powerful stable fm transmitter circuit my mail

    86. Sibaram Datta says: on November 1, 2012 at 6:51 pm

      I built near about 7 fm tr circuits that is available in the net as written its range is 2km its range is 5km & so on. But after construction its shows that with proper matching antenna all the circuits range is only maximum 500mtr. So friends beware of this circuits & westage of money. Any one can help me? Pls write to my email sibaram2datta@gmail.com. I want to ask Mr Craig to help me regdng this circuits.

    87. Senthilkumar says: on November 27, 2012 at 1:24 pm

      Pls provide me the price for prepared FM transmitter if possible

    88. please i am a final year student i want to build an fm transmitter that can be used for control purposes, i will graciously appreciate a detailed schematics sent to me.

    89. sabith2009 says: on March 18, 2013 at 12:32 am

      Sir am going to construct the tx, am already purchase all components except bb139 it s not available in our city, can i use any substitute for it.

      thank you sir

    90. sabith2009 says: on March 21, 2013 at 7:15 pm

      sir i constructed this circuit but i can’t able tune in my fm receiver ,am use the exact value of resister and capacitor but i use of bb122 instead of bb139 and my transister(2n3553) heated highly what i do ? am waiting for your answer

      • Follow the steps specified in the adjustments. You should have only the oscillator connected when you make the first try. If you cannot find your station there are some things you can do:
        1 – set the radio receiver at 88 Mhz
        2 – insert a ferrite core through L1 and adjust the 10k linear pot from one end to another.
        3 – if you cannot find it follow the next step
        4 – set the radio receiver at 108 MHz and do the 2-nd step again
        5 – if you still cannot find you fm station follow the 1-st and 4-th steps but this time insert metal screw (it can be aluminium too) through L1 and adjust the 10k linear pot

        You must follow these steps because it is possible that the original frequency of the oscillator is not in the 88 -108 MHz range and by inserting a ferrite core or metal screw you are changing the L1 coil value.

      • sabith2009 says: on March 27, 2013 at 9:22 pm

        i check all steps that u mentioned above but still i can’t able to tune freequncy
        i use following components
        1,varycap bb122
        2,copper wire (23swg,5 turns ,dia=4mm)

        i feel the bb122 is not suitable for this purpose i check the datasheet of bb122 its used in tv frerquncy
        can u able to help me if bb139 compulsory then i can buy from ebay. is available

        problem no2:
        my transister get heated highly what i do

        am waiting for your ans

    91. can someone please tell me more about the enameled copper and silvered copper?

    92. hi I have 2watt fm transmitter for sale if anyone interested please call me 9096934596.

    93. will u pls give me more details about this project?how it can be used in colleges?

    94. Hello my name is Axel, and i am from Greece. I am interested to build a very small radio transmitter to cover a humble area of 5 km maximum, because i the village i live there is ABSOLUTELY NO radio receiving from ANY STATION, so i decided to stop the drama in my village, this design here looks great, but it would be very kind if anyone could send me a detailed plan of the name of the components i will use to do my job. I than you in advance.:)
      my email: axel.sandi@gmail.com

    95. i have bought all the components but I’m still confused as to where to connect my terminals for the power supply to the system

    96. Can anyone tell me what 100 / 0.5W is. Am I right thinking its a 100k

    97. what kind of antenna do we have to use with this circuit?? and how can we shield this thing….

    98. the resistor after the L3 is mentioned like 58…68 and the capacitor T3 and T4 is 33…100pf. What does this means? What value of components do we have to use..???

      • 58 means 58Ω resistor, this is the way values of resistors is often mentioned. T3 and T4 are transistors not capacitors. All the values are presented in the schematic and article.

    99. is there any single chip particular ic for audio/voice transmission in should include mic also and for receiver if there means tell i want it so and i want range minimum 500m.

    100. plzz tell me i want to use inductor instead of coil L1,l2,etc… tell me the value of inductor or formula how to calculate??? plz tell as soon as possible…

      Thank you :)

    101. Can anyone get me a completed project. Most of the parts used are not in our local shops. If you can have an already working then you can sell one to me.
      +254720000185

    102. WHATS THE COVERAGE AREA IN KM FOR THIS CCT

      • it’s huge (with this power can be more than 5 km) if you have a very good antenna and low loss cable, and less than a few meters if you have a poor antenna and high loss coaxial cable.

    103. I needfm transmitter circuit diagram with no mistake

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