## Saturday, 5 May 2012

### LONG RANGE FM TRANSMITTER

Hello friends,
We know that building of Fm transmitter for first time is quite hard and we get confused about the components, parts, design, pcb, transmission frequency, inductor value and making of inductor , polarity of the capacitor and many things.

Here i am going to explain you a building of simple fm transmitter using a two transistor . I will try to explain as possible as i can. lets starts with the components required.

Transistor
Q1= BC547
Q2=2N2219

Capacitors
C1 & C2 =4.7uF(electrolytic)
C3,C4 &C7 = 100nF( ceramic 104)
C6 = 4.7 pF (ceramic )
C5= 10-30 pF (Variable capacitor or also known as  TRIMMER )

Resistors
R1= 47K
R2= 220K
R3=4.7K
R4 & R5 =10k
R6= 100 ohm

INDUCTOR
L1=  8 turns of 22 Gauge copper wire around a simple ball pen.( I will upload a photo of it for more idea)

POWER SUPPLY

Battery (Power Supply) = 12-9 V DC (Always use battery and avoid adepter so i will
reduce  noise in transmission )

HOW FM CIRCUIT WORK ?  :

The circuit is basically a radio frequency (RF) oscillator that operates around 100 MHz. Audio from audio jack is fed into the audio amplifier stage built around the first transistor. Output from the collector is fed into the base of the second transistor where it modulates the resonant frequency of the tank circuit (the 8 turn coil and the trimcap) by varying the junction capacitance of the transistor. Junction capacitance is a function of the potential difference applied to the base of the transistor. The tank circuit is connected in a Colpitts oscillator circuit. It works on the principal of COLPITTS Oscillator.

ANTENNA IS MUST IN THE CIRCUIT:

A impudence matching ANTENNA is must required in the circuit,without Antenna circuit will never works .Generally we uses a telescopic antenna . which through the waves in the atmosphere .

A SHORT NOTE ON INDUCTOR :

It is easy to make take an 22 Gauge enameled copper wire and wound it on the ball-pen and make 8 turns  on it tightly. i shown in photo below.

FM CIRCUIT CALIBRATION  ( IMPORTANT PART  :-     PLZ KEEP PATIENCE MAY BE                                                                   OF CIRCUIT  )                    YOU NOT GET SUCCESS IN
FIRST TRY OF

Place the transmitter about 2-10 feet from a FM radio. Set the radio to somewhere about 89 - 90 MHz. Walk back to the Fm Transmitter  and turn it on. Spread the winding of the coil apart by approximately 1mm from each other. No coil winding  should be touching another winding. Use a small screw driver to tune the trim cap. Remove the screwdriver from the trim screw after every adjustment so the LC circuit is not affected by stray capacitance. Or use a plastic screwdriver. If you have difficulty finding the transmitting frequency then have a second person tune up and down the FM dial after every adjustment. One full turn of the trim cap will cover its full range of capacitance from 10pF to 30pF. The normal FM band tunes in over about one tenth of the full range of the tuning cap. So it is best to adjust it in steps of 5 to 10 degrees at each turn. So tuning takes a little patience but is not difficult. The reason that there must be at least 2-10 ft. separation between the radio and the TRANSMITTER is that the  Transmitter emits harmonics; it does not only emit on one frequency but on several different frequencies close to each other.

Don't leave a circuit by just trying sometime try and try until you get some distortion in the fm receiver. once you get some distortion in it. that means your fm circuit is working. and if not then try to check all components and the soldering of your circuits and power supply .if you getting confusing about the power supply put one 2 Volt LED in series with 1K resistor in parallel with battery so you can easily get the on-off you fm transmitter.

ABOUT THE RANGE AND QUALITY (STRENGTH)  :
I personally maid this project with great success i got a 1 km perfect range with proper quality of the signal after that up to 1.5 km small distortion starts and after that quality factor go down and then lost it. you should have to maintain the circuit in the metal case to protect it form the electrical isolation .

The range and quality are inversely personal to each other. Both can be increased by increasing the input voltage upto certain limit.

I JUST UPLOADING THE PICS FOR YOUR REFERENCE THAT I HAD MAID IT LIKE THAT. YOU CAN TRY IT BY YOUR OWEN WAY BY MAKING PCB OR ON SIMPLE HOLED PCB.

 I used the simple copper plate and glue the other copper parts to place it on it

 A telescopic antennae of proper height.

 A inductor of the copper

A SIDE PHOTO OF THE CIRCUIT
If you have any problem and any question about it then you are always welcome.

From :
KALPESH CHHABHAIYA
(kpkpkalpesh@gmail.com )
mb: 8866792042

1. How is the quality of the sound? Would it be possible to use this as an amateur FM radio station? Is it possible that the range can still be increased?

1. Hello Unknown, i am about to build this transmitter, i got help from Kalpesh,i am sure it will work, i read on various sites that if you put in place of 2nd transistor one stronger like KT920A, BLX65, BLY81, 2N3553, 2SC1970, you will get longer distances.

2. thanks dear i m gaurav garg electronics engineer ,i will try this circuit,bt tl me one thing about the range of MIC.7568164083

3. 4.7 pf not avalabel others pf?102,103,104,68,22,47 pf

1. Its simple...Take two number of 10pf capacitor and connect it seriously it will give the value 4.7pf..

2. 4.7pf is good as 5pf .put two 10pf in series you'll have 5pf

4. Hello UNKNOWN
The quality of the Fm transmitter is very good as compare to the other local ones. And about the range of it can be increased by using a proper impedance matching Antenna at proper height above grounds.

no you cant use ceramic capacitor. you have to use electrolytic capacitor, you can use 10-4pf any capacitor but you have to use electrolytic capacitor.because it is used to filter the input signal of the audio signal.

1. Kapesh the guy was talking about a 4.7pf not a electrolytic

5. hello mr. kalpesh, i'm from indonesia.. i've been looking for this circuit to make my script,..

may i have ur email so i can ask you some advice..thanx before...

6. YA SURE ALWAYS WELCOME, MY EMAIL ID IS kpkpkalpesh@gmail.com . And it is already given in above description.

7. Can I get d receiver circuit for tis transmitted ckt??? Plz mail to me at arun.arunsurya.surya0@gmail.com

1. ya sure can, right now i am also working on 4-5 circuits, after getting perfect result of the ckt i will sure upload it and inform you.

8. Plz tell me about C6=4.7 pF is it ceramic or electrolytic and also what value i can us if 4.7pF is not available. also 22gauge inductance wire is it SWG or AWG.

1. Hello alisufian C6=4.7pf is electrolytic it is already mention above. And if you cant get if cant get it then you can use its nearest value capacitor but it should be electrolytic in nature. and the 22gauge inductor wire is in SWG, if not available the u can try for next type also, it dont create any problem for u.

2. sorry boss i was telling about the C1 & C2 is electrolytic but C6 is ceramic capacitor.

9. is 4.7pf available as 0.0000047uF cap?
Can I see how it look like, actually i couldn't find any electrolytic cap range in pf value.

1. sorry for my confused answer reality C6 is ceramic and i will E-mailed u a photo of it just give me a mail address ................ :)

10. hello sir, i have done build this circuit, but i'm still wondering why can't reach a km or even 100m. i placed the circuit on my house 2nd floor next to window, and my house is in top on hill too. mine still in breadboard, with telescopic antenna attached, and 18-18.5V supply (series of 9V batt or laptop adaptor plugged to voltage stabilizer). could you give me more specific about the inductor, it's length and diameter. thanks.

11. Hello Dimas
first of all you have to use pure DC without AC component like DC BATTERY, because AC will produce a harmonic distortion in the circuit so else same at output in FM. and for long TRANSMISSION you have to use 12-18 DC(pure) and the antenna you have to use a dipole antenna as we are using for TV which is maid up of aluminum at certain height from the ground with two connection one at collector or 2219 and other at ground. and then also u not getting the long transmission then reduce the value of the R6 resistor below the 100 and 50 ohms but take care that 2219 will not going to heat to much and bust.

12. thanks for your response sir, i'll try again.

13. hello sir plzzzz add me on my facebook bcz i want some help my email jawad_ahmed56@yahoo.com

1. you can mail me any time i will sure help u to solve the problem .

14. Hello sir,
How did you design this circuit?
or you copied from somewhere?

i mean, i never had such a beautiful idea in my mind to design FM-Tx.

1. I got this idea from my one subject book. Then i started to find more data about it and finally i maid it after a long journey of google search and book reading ............

15. hello sir,
in my city we are not finding the variable capacitor,
instead of it,is there any alternate component...?
help us... thank u

1. Hello jayachandra

variable capacitor is used to change the value of the output frequency. if you are not able to find it then you can use the capacitor of fixed value but the value should be between the 10-30 pF,then you get the frequency constant which you cant change it ,ok may be are getting what i want to explain :)

16. And ya friends in next week i am going to add working and frequency stabilization video of this circuit. So be connected to blog .

17. Sir,

The video??

1. ya Sure i will but right now i am busy with my exams so not getting so much time to do that but i will it on next 2-3 day sure :)

18. can you help me for frequency stabilizetion for this circuit, can we ad any tipe crystal for more stability? sanjaytupkar5@gmail.com mob.9096934596

1. you can use a 7812 voltage regulator in the power supply to stabilize your in put dc voltage. mainly the frequency changed due to the change in the input voltage level. ya we can use crystal but we have to add PLL circuit extra to lock the frequency at one desire level.

2. can i operate this at 9v.dc? because i have 7809 v. Regulator ic, for 7812 ic input volt need more than 12 volt & i think we cant available this type battary.

3. please publish stable frequency transmitter by 2n2219

4. yes, you can use 7909 but it will give you a very less range may be in hundreds of miters. and ya i am right now working with PLL fm transmitter which give stable frequency, and i will share after proper circuit of it.

19. I made this circuit , it is working too. but a lot of distortion at receiving side with low quality of signal strength , can you please tell me how to solve this?

1. If you put your hand over it and disappears means transmitter is not stable

20. First of all tell me which power supply you are using ? and how much dc voltage ?

1. 9 volt DC(Battery) , and other things are as you have explained above.
when i bring hand somewhere near antenna , then audio signal at receiver varies ,
and at some instant i get good quality of audio too.

21. the circuit that you made is working properly or not? Is it having good audio quality at receiver?

1. Ya sure it is working fine with good audio signal as it is mono u may not get good to here it . but it depends on the how you making the circuit and power supply of pure dc and constant voltage .

22. obviously yaar ,
9Volt DC Battery supplies pure DC , and i am using Desktop's audio output as a Nice Song , but i short both the Channels(Right and Left) . and antenna hight is more than 2 feet .and other all connection are perfect . though i am not satisfied with the audio quality . The noise of shhhhhh.....fshshhhhhhhhhshshshshshshshsh...shu shushuuuuuuushuuuuuusssss comes with original audio at receiver end .
WHAT DO YOU THINK? WHERE SHOULD BE THE PROBLEM?

23. problem is that you are using a audio signal of a DESKTOP which run on ac. but u have to use the audio signal of a device which is not connected to directly to ac or which work on dc example your mobile device. Try it then tell what happen.

24. Am Femi, Sir This is a very nice Job which am interested in, and thanks so much, am about to biuld mine, i just want to ask if its a must than my antenna must be on the cct like your? Cant i place the antenna outside the house and use a long wire to run it to the circuit? I will be glad if i can get an answer as soon as possible. tanx

1. ya sure u can, but you have to take a coaxial cable to do the connectivity between them and dont use the wire with high impedance.

2. 10metres of rg58 gives you best results and Use a good dipole cut to length for each pole will give you a 1.1 swr and also should make 50ohm dummy load for your circuit to test the swr before antenna and for kapesh telescopic you should take that out and try it if swr is bad with that transmitter then bin it

25. Finally After getting some time i uploaded a video of the Fm transmitter specially for its setting up and working , my be it is helpful to u people. i tried best as i can for it. as many friend had requested me to do this. and plz ignore my English.

2. As i already added to the blog. see at the bottom of it then also if you want then http://www.youtube.com/watch?feature=player_embedded&v=LI7fbz0B-rY

26. Sir, am sorry that am asking another question here again, when am about to go for the components, i discover that C1 and C2 looks like 4.7 pF on the diagram and its 4.7uF on the component list, so pls what is the true value of the capacitors? and since electrolytic capacitors use to have Voltage rating, which voltage will i go for? I will be glad if i can get the answer as soon as possible because i want to go and get the components now. Thanks very much

1. Hello Olufemi Ayodele

C1 and C2 are in uF just see the picture form near. u is looking like p in the picture.sorry for delay in reply.

27. sir, what of the voltage value of the electrolytic capacitor??

1. You can use any capacitor which is greater then the 15V , because the here the use of the capacitor is to just block dc and pass ac.

28. Is it compulsory i use a ceramic capacitor?? cant i use an MKT Polyester in place of that???

1. ya u have to use the same capacitor between the E and C of 2219. Other u can change it or use any capacitor.

29. how to calculate the frequency generated by tx.

1. U can do by mathematics equation , and also by device will known as GY-560 Frequency Counter Detector for radio 50 MHz ~ 2.4 GHz TH-UVF1. AND last method by manual tuning of the transmitter and putting the receiver at one frequency .

30. mr nigeria frnd mr femi. U can use polyester dats if t is in pf. Bt i doubt if there is 4.7 pf cap in polyedter forn

1. but its value should be same. because our ckt work on the colpitts oscillator so value should not be changed .

31. Can I add extra voltage through the mic to stepup the audio signal?

1. ya sure u can add mic and also extra voltage. but it should be stable and pure dc.

32. i am going to make this one plz advise me.

1. ya sure but i have already put all data which i have with the video in it. if you have any question then i surely help you as i can .

33. can i use 4.5pf instead of 4.7pf ceramic capacitor

1. U can try but i think 4.7pf is must for colpitt oscillator in the ckt

34. Dear sir,
i m ajay m mane frm satara, maharashtra.
Sir, i m a student of electronics engineering in 2nd year.
Hi sir , i have seen your 1km range FM transmitter and i have designed it as per the ckt diagram u have given, but sir i m facing some problems plz sir can u help me regarding with this.
Details of my designed ckt are as.
In market i have found all the resistors R1,R2,R3,R4,R5,R6.
In transistor for Q1 instead of BC547 i have using BC548 as Q1, and Q2 as 2N2219 as it is.
Capacitors C3,C4 and C7 are 100nf i.e. 104 code ceramic capacitors. The C1&C2 are 4.7 micro farad (electrolytic) but they are not available in market so i have purchased 10microfarad,10microfarad,22microfarad this three capacitors and they are connected in series for each C1 & C2, so i hve get C1 &C2 each of 4.08microfarad due to the series combination of three capacitors sir is this acceptable? This is my first query!
Then C5 is a trimmer capacitor and its middle and left hand side terminal i m using to get variable capacitance, is this correct na?
Then sir as u given C6 capacitor is 4.7 picofarad ceramic type capacitor but it is not available in the market, so sir, here which capacitor i have to use? this is major problem in my ckt!
Can u show me that capacitor,
then, for L1 i hve used a 0.75mm non enamelled copper wire having 8 turns on a plastic former and connected in the circuit . Is this correct?
For antenna i m using a telescopic antenna of height 2feet i.e. 60 cm.
So when i put the ckt on by using 9 volt battery then, i have detected that, sound output will present at the emitter of the 2N2219 but i think due to wrong value of C6 there is no transmission takes place , now i have connected two 104 capacitors in series at the place of C6 i knw it is wrong so sir plz tell me what to do with C6
i m sure sir with ur help i will definately get success in this transmitter design.
Sir i will send u a image of my transmitter ckt design.
And sir on fb i have sent u an friend request.
Plz sir help me
thank u so much.
My email id is ajaymane270@gmail.com
and contact no. Is - +919766712479

1. Hello ajay mane

Electronic is simple if you start playing with it , It is to hard if you just think that it work or , i said just try every thing rather then thinking that it will work or not, as ask some query you can also try for each . and in the electronic every thing is possible but you should have to hard work ............................. And then also any problem email me .

35. Hello, Sir.
I wanted to make this little project. I live in Mexico and at least in my zone it's a bit difficult to get some components. I was wondering if I could change both transistors for; 2N2222A and BC547-B ? Also, I cannot find the trimmer capacitor on the market... Do you know what I can use or do instead?
Thank you,
Great project.

Tobias

1. You can use use many transistor but just you have to get the DC load line configuration , and ac sine wave amplification.

36. Hello Kalpesh!

Have you got any idea, how many weight is this product?
How many could be the lightest version ca.?

Thx!

Laszlo Benke

1. Laszlo Benke
Try it you can easily make it.Rather then courier. already i provided every thing on blog like video, data , pics

37. hello kalpesh...
i am unable to find C6=4.7pf in the market can i use 5pf instead of 4.7pf capacitor.......

1. ya sure you can. In electronic for the filter work you can use near by value capacitor ........

38. dear sir,
i am from nepal, student of 3rd semester of EEE,
i wanted to design FM sa you posted above. it is my first try, if i got any problem i will contact you so plzz help me as possible.....

1. Ya sure i will but you just have to start work with full enthusiastic way. because in this you should have to work hard. :)

39. Hello Sir,

I am try to built your circuit.But T2 2N2219 not available in my area.Which Transistor appropriate for replace 2N2219.

1. 2N2222 CAN ALSO GIVE YOU DESIRE OUTPUT BUT ITS RANGE WILL GET AFFECTED BY THAT. IT WILL DECREASED.

40. Can I send Data (without audio) by this circuit? ( i was thinking about TX and RX)

1. ya sure you can but you have to use one audio signal for 1 and other for 0, and compare your output signal at the output using any type of the compare-tor like 741 or any op-amp.like wise making logic you can send the digital data using fm transmitter.

2. I have a LM339 circuit with 4 output and one ground which I used in Parallel(LPT) port. How can I transmit the signal by this transmitter. Then how to decode that in the receiver end?

41. This comment has been removed by the author.

42. hello sir
can I use a ceramic capacitor or not.

plz help...

1. Bro it is ceramic and it is clearly written their.

43. hello.. sir
there is a little confusion about trimmer capacitor for connected in circuit.. there is three pin.. how to connect..?

1. It has three lag so you found that two pins are in-font of each other are short circuited so use one of them and third one

44. Sir, your ckt is great!
:)

I made it, & its working fine!
:)

:)

Sir, can you guide me that how to design a FM transmitter for a particular frequency?

& Sir, I'm finding much problem in tuning the frequency, I receive audio signal maximum for 15sec. what should I do to sort out this problem.

Thank you Sir, & I appreciate your work from bottom of my heart.
:)

1. Always welcome. ok use PLL in your circuit it stable your frequency and allow u to tune in particuler frequency .

45. Sir, Tell me about C5 connection in the ckt because it has 3 pins.

1. It has three pins ,so you found that two pins are in-font of each other,they are short circuited internally, so use one of them and third one which is alone.

46. Sir, I m Mhoan Your work in only Fm Redio but not work in Mobile fm Plz suggest

1. Please tune mobile properly. because if it work in radio then it 100% work in mobile because it is frequency which can get by any one.

47. sir tel me alternative of 2n2219 i didnot find 2n series

48. sir. i am a electronics engineering student 3rd year... i made this circuit with all of correct component.....and used 9 volt pure dc,audio input was my mobile, or tablet or my laptop.....bt its range only 50 meter and audio was not noiseless..... a telescope antena with 2 meter long ware i used.... now what can i do? there is any another circuit ,that can give the perfect quality?

1. First of all you had used 9 v dc change it to 12-18 and move ckt far from ac wire . and also add dipole antenna. then also not work then tell me

49. Sir, do you have the GY560 Gooit frequency counter? I also want to buy it but not getting anywhere in India. If you have it please tell from where have you bought it or if not please suggest some store where it is available.

Thanks

1. no bro don't have, i tried but yet not delivered . just use ebay.com for buy

50. I want to ask that can I make use of a 12VAC transformer and rectify it to DC instead of using battery that one will have to change periodically? Pls I need a quick response sir.

1. you can but ac has harmonic so it will created distortion in output

51. Sir I was unable to get transistor 2N2219. Is there any substitute for it? It's urgent.

1. use 2n2222 but it has low output

52. Sir can I connect three jack input in parallel?

1. yes you can but it will mix all audio

53. Thank you i did This Project Very Well.

1. how to give input audio to circuit ? from 3.5 mm sterio jack female ? and how to connect the 47k pot ?

2. welcome. and sorry for late reply. you just simply connect r and l on upper side and ground to lower

54. hallo sir
i am work at fm transmitor project . Circuit ready but not recive frequncy in fm reciver
plz help me....

1. Please don't loss your confidence, just follower the troubleshooting rules which i had given in the blog

55. Thanks for your reply. Sir, how can I regulate the audio mix? The lower part of the circuit that is supposed to be negative with reference to the negative supply is positive. How can I rectify it? Does plastic casing has any effect? Can omni-directional antenna work as outdoor?

1. Welcome . For audio mixing you have to use the pre-amplifire befor the mixing of signal this preamplifire will provide the preamplified signal with same output resistance so in will never cliping of the other signal will heppan. you dont have to take any tension of negetive part it will preamplified by the preamplifire. And for shilding use metal casing because plastic will never create any effect to the noice signal. Ya 100% work but for that you have to add Rf amplifire with matching Resistance of that antena.

56. inductor is looking diffrent in your image than you explain in blog, in image ther is more than 8 turns.....

1. Inductor looking defferent because i used the copper wire with high SWG around 24 SWG. And you have to use 22 OR 20 SWG . by this it will changed the turn .

57. Pls what is the value of inductor as I'm unable to get it.

1. Dont go through the value of inductor just go through the Trial and Error Mehtod this will give you a proper output .By the value you get confused with output frequency . and i also dont know the exact value of the induactor.

58. Sir I'm still not getting any output

1. Try and try ..............

59. Sir the emitter part of the circuit where negative supply is to be conneced is reading a voltage source which is not supposed to be. What can I do?

1. just read the proper data and circuit arrangement............

60. If u don't know the value of the inductor then how did u come about 89.4MHZ?

1. This is called trial and errer method . try and check it .

61. you'll have to tune the circuit by tring more values of the components... den after you'll get the output.

1. Ya by this way you can also get output..........

62. Since regulated power supplies gives harmonics how can I correct it? Because I'm building this project for a Finland year student who doesn't want battery as power source. Now my output is not clear as the one u displayed on the video.

1. By using filter circuit at the output of the Power source like Capecitor and inductore filter.which will give u a perfact dc output without Ac harmonic at output.

63. After doing it (filter), how will I how that I have a perfect DC output void of AC harmonics?

1. Filter will give you a perfect dc output.you don't have to do any thing else.......

64. Why do I have to use RF amplifier? This circuit, can't it work for an external antenna (I.e. Omnidirectional)?

1. Because Output of the transistor is not much that can drive a antena....

65. I'm experiencing lots of interference. How can I eliminate them?

1. use a metal box to put the ckt. so it will reduce the interface of the external environment

2. Now I ve used the filter u recommended stil no signal I'm about giving up bcos I will call the student

66. hello sir could this ckt will work in the range of 90MHZ to 105MHZ

1. Ya sure . you just have to adjust tank ckt as per that .

67. dear Kalpesh sir ,
i'm a student of 12th and live at Agra
want to do something like this . and surely want to know about all these component .
i'm sorry i'm saying out of post . . . but i want to know what component works for what .
'cause i'm very curious about these parts . . . and want make my own .
can you suggest me . . from where i can get started

1. and if there is any book for beginner . . than please suggest me

2. just google each component you can easly get information about it, dont west money for buy book.

68. sir how to connect the min in this because it have two terminals and one I've connected to 47k and 2nd one to the GND .. but its not working ???
and can i use 9-22pf instead of 10-3-pf trimmer

1. Just short Left and Right and connect to 47k and third to gnd, and yes you can use 9-22pf

69. Sir suppose signal is 3 kHz then carrier wave will be 300Mhz
correct me if I´m wrong please
also the carrier wave is constantly changing so the antenna length would change too by this equation http://vsagar.com/wp-content/uploads/2011/12/screen50.png

1. Ya it must but you can as per your requirement. and i am not able to open the link plz correct it

70. Sir Please Tell me the how many watt for resistor value from R1 - R6. Please Sir

1. as i know you may use 1/4 watt resistance for this

2. ya 1/4 or 1/2 can also work same for us.

71. Please anyone can suggest me. how many watt the value of R1 - R6.
1/2 watt, 1 watt or 2 watt. kind your regards

1. just use any it never make any big change for us in this ckt.

72. can i use 2n3553 instead of 2n2219a

1. yes u can but just check its dc load line working area in its data sheet, and adjusts other component as per that.

73. can we use mic instead of audio jack?

1. yes u can but change the resistor R2 and R3 as per mic .

1. As i know gil .... yo can't .
'cause there is no comparative of this as vhf... it is just one... but you may use n2222A ..

2. no u cant because 2sc1971 is a HRf amplifire and u can do as Anurag Singh Raman said.

75. can i ask e circuit for the pcb of this project sir?

1. It is easy just do it by simple hand path drawing.

76. thank you sir i've completely made this .....but getting a distortion with it ..... i'v tried as much i can .... please tell me what is the main reason of the distortion . . . except dc supply .....

1. Just use metal cover and Make Strong Dc supply.

77. hey guys if you are not getting 2n2219a in your local region go through below link

78. anurag sir,please can i ask in your test how many kilometers the transmiter can recieve?is it stable frequency?

1. no as i know it does not transmit a stable frequency .
But if you want a stable frequency then supply a constant voltage power supply like 12 volt to 9 volt using voltage regulator (7809).... and for that the range of the transmitter will also be reduced . . . below 1 km ....but the frequency and the range will be exactly same . . . :)

2. Yes u can do the as Anurag Singh Raman Said.

79. woh what a circuit that is!!!! really its working very very fine.it is my first fm transmitter project and i get success.

1. what is the range of transmission?

2. Happy to hear that your Ckt is working fine .

3. Hello Dear,
I saw the circuit diagram of an Fm transmitter i had to tell to that i am really thankfull
for such a help.
i have to understand the working of different components and blocks used in the circuit i would be great full if u help me with that. please tell me the purpose of working of the components used in the circuit :)

I am looking forward for your help
Thank you

80. can i get an approximate cost of the antenna?

81. i made one but not get success ,can you help me sir ?i've used here 4.7uF 63v two capacitor,1/2 watt resistor 104-16v capacitor,2-22pF trimmer capacitor one teleiscopic antena BC547 AND 2N2219 transistor 8 turn coil L1 but not know that is it 22 gauge? and not get success when i start this with 9v battery then i don't get any signal in my mobile FM so please help me sir.and i've tried to rotate trimmer also but not get success.please help me sir.THANKYOU

1. ha ha ha . . . . me tto having the same but bro if you will use a small fm tuner specially . . . specially than you will get the tone .... good luck

2. till now i didn't get any tone in my fm tuner

3. ohk ... than definitely you did a mistake in positioning the component
check the connection to the electrolytic capacitor . . negative to negative for both electrolytic capacitor ... and than specially check the connection to transistor ..... or you may send me the pic of that . . some i can help you
anusinra@gmail.com

82. hello bro i can't find 4.7pf ceramic anywhere please send me its code and picture or other suggestion and their codes and pics. i will try to find in old ckt's
e-mail:: khzeshan5@gmail.com

1. ha ha ha . . that is rare product for this ckt . . . check the below link..... :)
.
http://www.electroncomponents.com/4.7pf-ceramic-capcitor?filter_name=4.7%20pf

2. i already have seen this site i want to know code of this...

3. sorry bro . . . but for what about you are saying that "code "
what type of code you want ??

83. Hi sir i m vasant i mail u 2ice but cant get reply . Plllzzz reply me sir i want help from U

84. Could I use the Transistor 2N2222A instead of 2N2219?? Because it is not available here!!

85. This comment has been removed by the author.

86. if i add one more 2n2219 transistor at parallel then does out put power increases??????? or not?????

87. hello , can u tell me that how to make vk220j type rfc inductor ?

88. hello sir,
i have bought all the components but i have 5pf capacitor instead of 4.7pf ,does it works?
one more question that the gauge of the wire also effect the frequency output?

1. sir you can buy the 5pf variable capacitor( trimmer) and adjust it value to 4.7pf
regard iftikhar

2. Sir Iftokhar izhar,
i have made this circuit and it is works sometimes perfectly but when i switch off the circuit and turn it on it donot work.then i have to set the trimmer .

3. 1) i have also this problem, but with constant dc power supply your circuit works properly...(2).and put the circuit with a proper place.

89. this is a good circuit and i made this . interested

90. I want 20 Km fm Transmiter

91. i hate ur last sentence :/ ......... i.e (SORRY FRND FOR MY POOR ENGLISH) ............. v want ur idea and also v respect for ur great struggle :)

92. ei kalpesh,is coil a very importnt factor to do this project?im working on this project right now

93. This transmitter will have 400-500mW@12V at the output. It will NOT have 2W with 2N2219A for sure...

Cheers! ;-)

1. Oh, and if you want some better output and distance, you could try to put 2N4427 instead of 2N2219A, :-))

94. cai use 2N2218A instead of 2N2219A ?

95. Hi Sir, I am doing this for my degree assignment. I had built this according to your component list, but when I check with spectrum analyser, only carrier frequency is transmitted and no audio signal is modulated inside. My radio unable to receive the audio. may I know why? Thanks.

96. Hi, Thanks for taking the time to write up a great project!I'm hoping to use the circuit with a michrophone similar to the data sheet below, is this possible? http://www.farnell.com/datasheets/1505851.pdf
Regards
David

97. Hi iWork's also like to know why on your picture your coil is facing in opposite direction of what the schematic shows .is this a different transmitter your showing from the diagram ? It's not laid out the way it shows in diagram and your resistor values are different thanks

98. Also your coil turns are not same and you have different swg in there .and it's not a guessing game if use 28swg then means I would have to use less turns .and for your 22gauge you must of at least had 8 turns .if for that matter 20 gauge you must of had at least 10 turns are my right ?

99. I also have to say see I don't use 100k resistor connected to emitter I get a heat off the transistor which is supposed to do .so why is there a 100k resistor connected to the emitter ?

100. If your the true author then at least correct what you did your resistors and your coil and your layout is different to what we see in oscillator .so if your working us to get it to work would you not at least say how it's done ?.i mean if I put a website up and showed it properly would you not get a thanks for showing it properly and working like you say it showed ?.when I go through the comments it's like your trying to get them guessing .you would get praised for showing it how we see it means next time you build something your trusted .idea is show it how it is and not falsely information

101. And for use that are stuck at getting 4.7pf .you can grab two 10pf put them in series gives you 5pf .put the capacitors beside each other put one of the legs on top of other capacitor teist the legs then don't use them on the board the two single pins should be used connect single pin to the emitter other single pin to the collecter now you have 5pf in series .

102. Teist that was meant to say twist stupid predictive test

103. please sir l want to know how many feet your transmitter covers without the aerial

104. The FM transmitter how to work on explain the Long range Metal Detectors | Detech metal Detectors

105. Hi mr can you help me i made that but i have problem i cant find frequency to my transmitter, i use 9v baterry and phone for music