The proposed long range transmitter circuit really is very steady, harmonic free design which you can use with standard fm frequencies between 88 and 108 MHz.
Technical Specifications of the Transmitter
This will likely encompass 5km spectrum (long range). It includes an extremely consistent oscillator for the reason that you employ LM7809 stabilizer that is a 9V stabilized power source for T1 transistor and for frequency realignment that may be reached by means of the 10K linear potentiometer.
The output strength of this long range rf transmitter is approximately 1W however may be more significant should you use transistors like KT920A, BLY8, 2SC1970, 2SC1971…
Transistor T1 is employed as an oscillator stage to present a small power steady frequency. To fine-tune the freq. apply the 10k linear potentiometer this way: should you moderate, in the direction of ground, the freq. would probably decrease but when you fine-tune it in direction of + it would climb.
Essentially the potentiometer is needed just as a flexible power source for the a pair of BB139 varicap diodes.
Both of these diodes function as a changeable capacitor whilst you regulate the pot. By tweaking the diode capacitance the L1 + diodes circuit renders a resonance circuit for T1.
Feel free to employ transistors similar to BF199, BF214 however be careful not to use BCs. At this point you don’t receive yet the long range fm wireless transmitter due to the fact that the electric power is fairly reduced, a maximum of 0.5 mW.
How it Works
The proposed transmitter circuit works in the following manner:
Always encase the oscillator stage in a metal guard to avoid parasite frequencies destabilizing the oscillating stage.
Transistors T2 and T3 functions as a buffer stage, T2 as a voltage amplifier and T3 as a current amp.
This buffer stage is vital for freq stabilization simply because is a tampon circuit between the oscillator and the preamp and final amplifier. It happens to be renowned that bad transmitter layouts normally change freq. whenever you alter the finalized stage.
Using this T2, T3 stage this won’t occur again!
T4 is a preamplifier stage and is employed as a voltage power rf amplifier which enables it to produce adequate power to the ending T5 transistor stage.
As is demonstrated T4 carries a capacitor trimmer in its collector, this is definitely accustomed to render a resonance circuit designed to drive T4 to promote more advantageous situations and do away with those undesirable harmonics.
L2 and L3 coils has to be at 90 degrees perspective one to another, this is to prevent frequency and parasite coupling.
The concluding stage of the long range rf transmitter is equipped with any rf power transistor containing no less than one watt production power.
Utilize transistors like 2N3866, 2N3553, KT920A, 2N3375, 2SC1970 or 2SC1971 should you wish to produce a professional fm transmitter with ample power to take care of an extended spectrum zone. Should you use 2N2219 you will definitely get a maximum of 400mW.
Make use of an effective heatsink for the T5 transistor because it becomes slightly warm. Make use of a reliable 12V/1Amp balanced supply of power.
How to Set-up the Transmitter
Begin by building the oscillator stage, solder a tiny wire to T1 10pF capacitor out and hearing a fm radio, tweak the 10k pot until it is possible to “hear” a blank disturbances or maybe if you connect an music base you could listen to the melodies.
With a 70cm cord it is possible to take care of a 2 – 3 meter region simply with the oscillator stage.
Next carry on and construct the remaining of the rf transmitter, utilize correct shielding as suggested in the above explanation.
As soon as you have completed the transmitter design, hook up the antenna or more effectively a 50 or 75 Ω resistive load and make use of this as a rf probe, feel free to use 1N4148 diode in place of the probe diode.
Fine-tune yet again the 10k pot to favored freq. thereafter go to T4 stage and scale down the initial collector trimmer for highest voltage signal on the multimeter.
After that carry on with the subsequent trimmer and so forth. After that get back on the very first trimmer and readjust yet again until you receive the maximum voltage on the multimeter.
For one watt rf power you could possibly ascertain a twelve to sixteen Voltage. The method is P (in watt) is equivalent to U2 / Z, wherein Z is 150 for 75Ω resistor or 100 for 50Ω resistor, nevertheless one should keep in mind that the proper rf power is lesser.
After those modification, in case things are heading nicely hook up the antenna, keep on employing the rf probe, readjust once more all of the the trimmers right from T3.
Guarantee you don’t have harmonics, verify the TV and radio set to determine if there exists fluctuations on the band. Verify this in an alternative area, a long way away from the fm transmitter or antenna.
The unit is all set up to be used for exchanging music, talks, chats across the suggested range and bands.
Circuit Diagram
All Inductors are air cored
L1 = 5 wounds / 23 SWG / 4mm silvered copper
L2 = 6 wounds / 21 SWG / 6mm enamelled copper
L3 = 3 wounds / 19 SWG / 7mm silvered copper
L4 = 6 wounds / 19 SWG / 6mm enamelled copper
L5 = 4 wounds / 19 SWG / 7mm silvered copper
T1 = T2 = T3 = T4 = BF199
T5 = 2N3866 for 1Watt / 2SC1971, BLY81,or 2N3553 for 1.5 to 2W power.
Feedback from Mr. Himzo (a dedicated follower of this website)
Hello Swagatam,
I have few questions about your long range fm transmitter.
Firstly about the shielding, what is the most simplest solution to avoid those "parasite frequencies"?
Secondly, what means those 1nF capacitors at the top? Can they be simple in parallel connection or they need to be separated to every transistor like in scheme?
Thirdly, I sent you a photo of transmitter, I didn't turn on amplifier part because my heatsink is coming. Where can I put antenna for testing without amplifier (T5 stage)?
And lastly, how can I modulate those trimmers if I dont have plastic screwdrivers?
Thank you very very much, this is great project.
Your fan, Himzo.
Solving the Circuit Problem
Hello Himzo,
the simplest and the only way to shield the various sensitive stages is by using metal walls between the stages...
the 1nF capacitors should be positioned exactly where these are indicated in the diagram.... the picture which you have shown will never work... transmitter circuits require extreme care as far as their construction and positioning of the components are concerned.
You can never build a long range transmitter successfully on a breadboard, you will have to do it on a well designed PCB which should have a grounded track base layout encompassing all the thinner tracks, only then you can expect the transmitter to work...that too after careful optimization of the trimmers and by employing a compatible antenna.
Regards
Melvin says
Hi sir 1) I would like to know whats the use of those variable capacitors here. I dont know how to use it
2) What is shielding. What is its use
3) Which component is 100/0.5w
4) 10uf capacitor is of how many volts
5) Why 2 dotted lines in circuit which is connected to ground
6) Why T5 is based on watts and what is the difference between 1w and 2w output
Kindly please reply to me at mevivrg01@gmail.com
Swag says
Hi Melvin, here are the answers:
1)Those are called trimmers, it is for optimizing the frequency and power output from the transmitter to maximum.
2) Shielding refers to adding metal partitions between the various stages of the transmitter so that processed signals across these stages do not interfere with each other and reduce efficiency, the metal can be preferably copper so that it can be fixed with the PCB by soldering.
3)100/0.5W = 100 ohm 1/2 watt resistor
4) 10uF/25V
5) The shield partitions explained above must be aligned across these shown dotted lines such that they stand like walls on these dotted lines…the height of these copper shield plates could be 2 cm and thickness could be 1mm.
6) T5 handles the power stage of the transmitter, and their watt rating indicate how much power each of these variants can handle and produce at the output
Melvin says
Hi swag its me again Melvin. Thanks for your reply but I’m a little bit confused of that first answer. So how to use those trimmers.
Swag says
Hi Melvin, please read the comments, I have answered it in one of the comment replies.
Melvin says
Thanks swag
varun says
I have recently build lots of low power fm transmitter all claiming about 1km range but at most I could get 500mts only. I am not able to tune the circuit meaning to say that the oscillator and the tank circuit are not at same frequency and because of that I am getting signal at many places on fm band ie harmonics . how to tune such transmitter pls help. like in this you have got 4 trimmer capacitor how to tune them? which one should I tune first.pls help
Swag says
disconnect the last T5 stage which has the antenna, and optimize the two trimmers to get maximum silence (null point) in the FM radio positioned at about 10 meters away, once this is achieved connect the T5 back and repeat the process without an antenna at a greater distance away from the transmitter.
jamil says
Hello again sir swagatam I have no idea what component that bb139
Swag says
Jamil, that’s a varicap diode
https://en.wikipedia.org/wiki/Varicap
jamil says
Sir its possible to put crystal oscillator in transmiteer and receiver.
Swag says
I am not sure how to do it, if you know you can try
PAKPA OINAM says
Hello sir, My name is pakpa. I want to know something that is there any possible way to convert rc remote control car's remote to fm transmitter. Kindly help me.
Swagatam says
Hello Pakpa, yes that may be possible by first converting the voice signals into digital mode through a class D amplifier circuit
yasif peerally says
Hello Mr swagatam.yasifpeerally@gmail.com many thanks again for the beautiful design of your fm long range one watts transmitter I have built and it work.
Swagatam says
thank you yasif, I am glad it worked for you, appreciate your efforts….
Unknown says
I want to do 5 kms FM transmitter but i have no idea because i don't no which things i should brought and where should brought and i don't no modul of board
Swagatam says
first you must build and try small designs, if you succeed with those, you can gradually go for more complex and long distance versions….
yasif peerally says
Well yasifpeerally@gmail.com please forward me your email address I will share my knowledge to you.i have not made a pcb to built the circuit I have built on stripe board I assure you that I got the range.
Anonymous says
Hi yasif peerally can you please share the PCB or the design you have used for making the transmitter
yasif peerally says
Hello thanks for long range tx circuit I have built it and it work beautifully Yasifpeerally
Swagatam says
that's great! I appreciate your efforts and thank you for sharing the info
Prasenjit Majhi says
hi sir i don't give some parts of my market. so you can help me?
my email- bubun43@gmail.com
wait your answare
Swagatam says
Prasenjit, In the article you will find many equivalents suggested for the transistors, so you can experiment with those alternate numbers…
Sharoj Al Hasan says
Sir will it work perfectly ? i want to make this .
I am new that will good if you can provide me more easy circuit for long long range transmitter .
Swagatam says
Sharoj, you can try the following circuit
https://homemade-circuits.com/2014/11/rf-signal-jammer-circuit.html
Arka Bhattacharya says
Sir,
I request you to kindly send me the complete list of parts, used in this incredible project.
Thank you in advance.
Swagatam says
Arka, please click on the diagram to enlarge and copy the part name which are mentioned beside the respective symbols, if you show this list to the shopkeeper he will understand and give you the required material.
but please remember this project is for the experts who may be well versed with RF concepts, it's not for the newcomers
Arka Bhattacharya says
Sir,
I am a law student and have not enough knowledge about radio frequency to make this project. But, I am very much interested to build a FM transmitter with not less than 5 km range. I will be very glad if you tell me the complete parts list and guide me further.
Thanks for keeping patience to help this newbie.
Swagatam says
Arka, If you are a newbie then you should proceed step wise and learn how to build basic transmitters first. Please try any of these models and see if you are able to succeed with them or not.
https://homemade-circuits.com/2014/08/spy-bug-circuits.html
Once you do then the next step would be to build a 500 meter range transmitter, and after that finally you could try the 5km range design
Arka Bhattacharya says
Sir,
First of all, thank you very much and "PRONAM". Now, I'm going to make that FM bug transmitter. I will be very glad if you also send me the link of 500 meter range transmitter. I hope, you will guide me. And again, thanks a lot for your prompt reply and guiding me.
Arka
Swagatam says
You are welcome Arka,
for the 500 meter transmitter you can try the following design
https://homemade-circuits.com/2014/11/rf-signal-jammer-circuit.html
Arka Bhattacharya says
Sir,
It will be very useful if you give a complete list of all parts used in this amazing circuit. You can mail me the list of the parts at arka6208@gmail.com or can post it here.
Thanks in advance.
Himzo Hasak says
Dear Swagatam,
Can I add MPX(stereo, RDS) at the audio input of this transmitter? In manual it says it can be transmitted by every transmitter that hasn't low pass filter at the beginning.
Best regards,
Himzo
Swagatam says
Dear Himzo, I am sorry I am not sure about it, you may have to try it out practically to know the results
Unknown says
what is to be used as input and output please help me
Sanjay Tupkar says
With 1971 transistor how much power can provide by this circuit??
Swagatam says
please mention the specifications of the transistor??
Soumen Bhowmik says
sir what is the meaning of 56…..68 and 68 ……100/0.5w what is that also???thanks….
Swagatam says
those are resistance values in Ohms
Anonymous says
can i use a phone through 3.5mm jack instead of phone please help me
Anonymous says
I have BF494 and 2SC1907. Can I use these instead of the BF199?
Swagatam says
No I don't think so because BF99 is rated to operate with much higher frequencies than the mentioned ones…
habtamu demeke says
i can't find the BB139 varactor diode, what other option can i use?
Swagatam says
any other equivalent will do….you will have to search for it.
habtamu demeke says
I almost got all the components except the component between
T4 and T5 labeled as 100/0.5w,connected with 10 micro farad, i don't know it's name and purpose.
can you tell me about the antenna and the pcb choice, please?
it will be nice if you put the video of how to construct.
Swagatam says
it's a resistor, a 100 ohm, 1/2 watt
please remember that RF circuits are never easy, and it must be only tried if you are well versed with RF transmitter concepts or under the supervision of an expert in the relevant field
initially you can try a 12 inch flexible wire as the antenna, if everything goes well then you can replace it with a yagi type antenna
video is not possible sorry
habtamu demeke says
hi swagatam i really like to build that fm transmitter but the circuit diagram is not clear. can you send me the circuit diagram at derui29@yahoo.com, please?
Swagatam says
Hi Habtamu, please click on the diagram to enlarge it, you will be able to see all the details clearly
habtamu demeke says
okay i got it. i can't find the BB139 varactor diode, what other option can i use?
Jamil Mindalano says
Hi swagatam can u tell me where is the negative line in the circuit.
Swagatam says
Hi Jamil, the black thick line surrounding the circuit is the negative line.
Jamil Mindalano says
Sir how about the 56k resistor are not connected the one terminal, but the arrow is center in the 10k linear.
Swagatam says
Jamil, the 56K upper end is connected with the center lead of the 10K preset…the arrow identifies the center lead of the 10k preset
Jamil Mindalano says
Sir what if i use a 2N3904 transistor in t1 to t4, because bf199 transistor is not avilable in our city.
Swagatam says
no it won't work
iyiola semiu says
sir gud job all the tm,sir i need circuit for 2km fm transmitter
Swagatam says
thanks iyiola, you can try the same circuit which is discussed in the above article.
vivian blinks says
how can i get the complete write up for this particular fm transmitter circuit,i was asked to construct it but am through with the construction remaining the write up need some help from you
ප්රේමෙ says
Thanks a lot for replying to all the queries Swagatam,
Can you mention the Inductance values of the coils used, so that I can get an idea whether the coil is woven correct.
Swagatam says
you are welcome!
RF Transmitter coils normally are not specified with inductance values because the values can be so less that your meter won't have the range to measure them…so the physical specs are the one that you'll have to rely on.
Anonymous says
Hi Swagatam, Is it possible to use this transmitter to transmit PWM signal to control DC Servo Motors? Would be grateful if you could answer the question. Thank Raj Sherikar
Swagatam says
Hi Raj,
yes it can be done…it is possible
Unknown says
heyy !! this is ritwik . i need to make a simple wireless transmitter and reciever of range upto 50 metres . the idea is to make a transmitter which could transmit the signals in the particular range of 50 metres and any reciever coming into the range must get he signals from the transmitter . please help me with this .
Swagatam says
Hi, you can try the following circuit:
https://homemade-circuits.com/2012/01/how-to-make-wireless-speaker-system.html
any FM receiver situated within a radial distance of 50 meters will be able to receive the signals..
For You says
OK
Moustafa Farouk says
what is 100/05w in the second stage? is it a resistor? and 10uf in the same stage ? is it something for a surface mount? because i'm working on a through hole board so what is its alternative?
Swagatam says
100/0.5W is obviously a resistor and 10uF is after this resistor
surface mount is not compulsory but will work better…make sure the PCB is maximum area merged with the negative line.
Unknown says
excuse me what is the audio and what is the output? is it microphone or aux for audio and antenna for output? and where is the vcc?
Swagatam says
audio is the input frequency which needs to be wirelessly transmitted to the other end and the output where the antenna is supposed to be terminated
shah hussain says
Sir, what is the legal range of fm transmisn in india without having lisence.
Swagatam says
beyond 100m it could be illegal…
leandro Piñol says
Sir does this transmitter will work the same with a two way wireless telephone system?
or if you would mind do you have a reliable two way wireless telephone Diagram
that I can borrow? 🙂
Swagatam says
leandro, if you include a radio receiver in conjunction with the above transmitter on both sides then it can work as a two way wireless system.
LUCKY C.S OZANO says
Hi Engineer can I use this diagram to transmit video signal?
Swagatam says
hello lucky, it may be possible, not sure though, just Google "video transmitter circuit" and you'll plenty of good circuits online.
By the way, you can also refer to the following design for the same:
https://homemade-circuits.com/2013/10/simple-tv-transmitter-circuit.html
suman das says
Dear Engineer,
If I want to get 10km Range then what no of transistor should be used in this circuit.
Also suggest what type of antenna is suitable for it ?
Swagatam says
Dear Suman,
the range cannot be increased just by changing the transistor, it can be much more complex than this….so it's not that easy.
LUCKY C.S OZANO says
Hello Engineer thank you for sharing this wonderful project. Please can I use this design to send video signal?
Swagatam says
hello lucky, it may be possible, not sure though, just Google "video transmitter circuit" and you'll plenty of good circuits online.
By the way, you can also refer to the following design for the same:
https://homemade-circuits.com/2013/10/simple-tv-transmitter-circuit.html
Adam Kabir Umar says
Engineer, I encountered a problem with the FM transmitter circuit. This was because of my system's resolution that I cannot understand the value of the upper resistor connected to collector of T1. It looks like 10k, 15k or 18K. Please, make it more clearer specifically.
Swagatam says
Adam, click on the diagram to enlarge it, and you'll be able to see everything distinctly….T1 collector resistor is a 330 ohm resistor…how do you see it as 15k, or 18K??
Adam Kabir Umar says
Engineer, I want to know the value of the upper resistor connected to the collector of T1. It is not clear to me. Thanks.
Swagatam says
It's 330 ohms
Adam Kabir Umar says
Engineer Swagatam, I wanted to know what type of microphone should be used alongside this FM transmitter. Thanks for attending my requests.
Swagatam says
Hi Adam, you can use any electret condenser mic for the shown circuit
Adam Kabir Umar says
Good day Engr swagatam.
I dad not seen the position of + line of my power supply.
Swagatam says
Good day Adam,
The L4 upper line is where a positive 12V needs to be applied.
Adam Kabir Umar says
L4 has two terminals, one is connected with T5 and the other terminal is connected to the 100 ohms resistor. So i should applied my 12v to the terminal that is connecetd with 100 ohms resistor?
Secondly, i am not understand the symbol of 10 uF capacitor that connected with 100 ohms resistor
Swagatam says
12V supply will go to the 100 ohm and L4 junction line.
the 10uF capacitor shows one terminal connected to earth, that's the negative terminal of the capacitor, the lower one, the upper one is connected with the positive line.
Adam Kabir Umar says
Sir, the normal variable capacitor has three terminals, so how can i connect the variable capacitors in this circuit sence the circuit diagram indicates only two terminals.
Secondly, i need more explanation about varicap diodes.
Thanks for this greatful work
Swagatam says
for the variable capacitor you can use the center terminal and any one of the other two terminals, the remaining one can be left unused.
varicap diodes change and adjust their capacitance value in response to the varying amplitude of the input frequency providing the most optimal input feed for the preamplifier stage
john ocharive says
thanks for your respond but I actually need a seperate receiver circuit instead of the fm radio reciever seperatly. what I actually want to do is incorporate the receiver into the transmitter system as a device for distance learning.
Swagatam says
For converting the above design into a long range walkie talkie you can make a small FM radio and use it with the above transmitter circuit but I am not sure how the units would interact while operating on different frequencies..
john ocharive says
I love this design I have made it but not tested yet because I need a receiver that can work for it. please post one to me please its urgent. because this is my final school project.
and how can I make another person talk back to the receiver from another transmitter.
you send to to my mail box at ochar2men@gmail.com
Swagatam says
thanks! in the article it's mentioned that the receiver is a FM radio, please read the setting up procedures.
Omkar Singh says
you can use mobliephone fm
Swagatam says
yes you can
ravi kiran says
sir is this circuit works by antenna???
Swagatam says
yes you will need to connect a 50 ohm terminated yagi antenna at the shown output points
saam says
hello swagtam , i need fm radio transmitter circuit which should be simple
Jansher Khan says
you have any simulation of this circuit?FM transmitter is my semester project and bb139 is not available in my city please suggest me any other varectror diod which i can use instead of it.
Swagatam says
sorry, no I do not have any simulation for this design. you can try any other equivalent for the shown varactor diode, it's not too critical.
please not that the above circuit may not be so easy for a newcomer, I would recommend you to search for a design which has a PCB layout.
naman says
is it possible to use this module as rc plane controller with multiple channel ? i want to make my own long range rc transmitter and receiver…
Swagatam says
sorry no, this cannot be used for such complex operations.
rechamsaad says
hi all !
it seems a good design and want really to realize it : but can anyone tell us where is the VCC + terminal ? it is not shown on the diagram?
Swagatam says
The line which is connected to L4 must be supplied with the positive.
baseer coorg says
Swagat wher got it BF199 transister in india
Swagatam says
Hi Baseer, you can get it from all metro cities in India, Mumbai, Delhi, Kolkata, Bangalore, Chennai, anywhere.
baseer coorg says
HI Swagatam How to Transmit 5km TV RF signal by air ?
Swagatam says
Hi baseer, to transmit video signals at long distances will require highly sophisticated circuits, i do not have it presently.
ABIN says
nobody try this, simply wastage of time and money, this circuit wont work.
I made this circuit exactly as diagram.
Swagatam says
the circuit is perfect and will work if done correctly as per the given instructions.
ABIN says
helo i bought BB122, i made up to T1 and 10pF capacitor, and as u explained above, i cant hear any blank disturbances in a near by radio, kindly help me
Swagatam says
you will need to build upto T4 minimum to make the transmitter work.
tomorrow i would be publishing another similar circuit, but with much easier design, i would suggest you to try that instead of this.
ABIN says
Hai, i am from cochin kerala india.i cant get BB139 here. so what. can i add as substitute.pls help me..
Swagatam says
Hi, you can use any VHF/UHF varicap diode in place of BB139, the value is not critical.
Try the one which are used in TV tuners.
ABIN says
Is varicap is nessessary or not.becoz am not geting any varicP here local.
ABIN says
can i use anthing substitute of this varicap diode, becoz am not geting any varicap here
ABIN says
I JUST WANT TO KNOW HOW MUCH DISTANCE IT WILL GO THIS TRANSMIT ION, obstacles like trees is a problem or not, become i am going to use in area little like a forest, so is this successful to transmit 1 km ?
Swagatam says
No, you cannot substitute the varicap.
trees and structures will not affect the transmission.
Amol Borkar says
hey swagatam, i'm trying to make a transmitter that can send a continuous signal to a receiver i dont have to transmit audio signals can that can be done with your circuit if yes how and what changes i have to make in your circuit to do that. Also can i change frequency of transmitter when its on.and how can i find which frecquncy is currently transmitted by the circuit. please answer my queries.
sorry for my bad english.
Regards
Swagatam says
Hi Amol, by continuous signal do you mean a blank signal which will produce a null spot in the receiver? It can be done by not connecting the input to any kind of signal source. keep the input connected to ground and tune the transmitter to get the required null spot in the receiver.
Amol Borkar says
Thanks for the reply Swagatam, acctully i'm trying to make a reciever that collects signal from your transmitter and sends signal or current to base of a transistor and another circuit is connected to emitter and collector of that transistor, so when base gets current the another circuit gets complete.Please he me to make the reciver circuit or is there a better way of doing it.
Swagatam says
Hi Amol,
I have discussed one similar application in the following article, you can refer to it:
https://homemade-circuits.com/2011/12/how-to-make-fm-remote-control-using-fm.html
Swagatam says
the better way is to use the profesional RF modules with encoder decoder chips, but those are within 100 mters range
Amol Borkar says
Thanks Swagatam, firstly my requirement of range is minimum 1 km as it is a aeroplane and also using the professional RF modules with encoder decoder chips need to be programmed and the will affect my budget the engine is ready but I need something to control the flaps.Can you suggest another way. I think that the same thing(Transistor part of my reply) can be achieved with AM technology I have receiver design but not sure that it will work.Please suggest me a AM transmitter design
Swagatam says
Hi Amol,
sorry, I don't have an AM transmitter design with me.
Moreover when it's an airplane that you want to control, only FM technology would suit better because AM could be inaccurate and include disturbances in the signal.
RF modules does not require programming, they can be procured readymade but I am not sure about their maximum range, I have never seen a 1km RF remote control device in the market.
Abdullah Al Shibani says
Dear Swagatam,
I would like to have a receiver for this transmitter for switching purpose, is it possible and logical??
or you advice me to better look for another kind of transmitter. Clarify to me please.
Regards.
kassimdandago says
With yooir permission i can commercialise the circuit.
Swagatam says
permission granted:) …anyway it's not my design.
BASHA says
ok thanq sir
BASHA says
ok thanq sir iam intrest long range fm transmitar circuit i made it ,so this circuit meterial components and cabinet your buying and send coriear my adress pleese sir ,this circuit price telme i paying your account pleese telme your nomber
Swagatam says
Hello Basha, I don't have a PCB for this design, and also I cannot find the transistors in my local shops, so I am also having difficulty in making this unit, in future if I am able to arrange all these I would surely do it for you.
BASHA says
hello sir iwant this fm transmitar sir so you made this circuit and send me my adress sir plees thanq this product money details send me my mail askmbasha30@gmail.com
Swagatam says
I am sorry Basha, it wouldn't be possible for me due to work load.
mahesh kunwar says
have you test this circuit and it is necessary to have the diameter?
Swagatam says
Not tested, yes diameter is critical
Anonymous says
Hi! I have a ready made car fm trasmitter which reads n play music on memory cards, but d distance @ which it transmitt is no more than few yards or so. Can u pls help with a circuit to boost it transmition rang to _+_ 10km. Could it b feasible? Pls reply
Swagatam says
what type of receiver is used for receiving the signals, is it an ordinary FM radio?
Anonymous says
Yes, it is an ordinary FM radio
Swagatam says
In that case you can feed the transmitter audio output to the input of any good 10km range transmitter circuit, the audio then would be transmitted across the specified distance.
ترفيه وضحكة says
HI how make receiver and transmitter for drone
Thanks
Swagatam says
https://homemade-circuits.com/2016/06/simplest-quadcopter-drone-circuit.html
shadrach says
can you give wifi signal transmitter and receiver circuit diagram for long range like 5 km to 10 km
Swagatam says
I don't have any idea regarding wi-fi transmission.
shadrach says
can i use this circuit for transmit my wifi signal within range 5 km ?
do you have any other circuit for transfer/receiver wifi signal in long range ?
Swagatam says
No, that won't be feasible because wi-fi signals are not RF based and will require different type of encoding/decoding process.
kassimdandago says
@umaryie@
gmail.com.
Try to be careful not to transmit without licence. Your country is v.careful about transmission without licence.
Umar Faruk Mohammed says
Hey swagatan , i'm new in dis ur wounderfull an very intresting blog, I'm a computer science student i need some help about that fm transmiter u are talkin about, all those thing u name the requiremet i dont no how to arrange them to form the transmiter circuit pls help me , an u can send me more explaination on my email: umaryie@gmail.com.
Thanks regard.
Swagatam says
Hi Umar,
The above design would be difficult to build for any beginner.
You will have to first order make a well designed PCB, and then assemble the shown parts corrects and then adjust the parameters with a lot of care.
kassimdandago says
Welldone Sayyad, i hope you can make one.
If i understand your question, the circuit is only a transmitter and you can use ordinary fm radio and receive your broadcast.
kassimdandago says
That means you have to build a tranmitter and a receiver for a 2way communication. Is there a way of making it a tranceiver? When applying an audio to the modulator stage can you create a wave form within the audio frequency spectrum and mix it, and at the receiver stage intergrate it to produce the real audio eg a 1khz tone ? Thanks.
Swagatam says
it would be a very complicated circuit….
Prof.K.V.George says
Dear swagatham,
Please explain the following coil (especially sivered copper and enamelled copper)
L1 = 5 wounds / 23 SWG / 4mm silvered copper
L2 = 6 wounds / 21 SWG / 6mm enamelled copper
L3 = 3 wounds / 19 SWG / 7mm silvered copper
L4 = 6 wounds / 19 SWG / 6mm enamelled copper
L5 = 4 wounds / 19 SWG / 7mm silvered copper
Swagatam says
Dear KV George,
wounds refers to the number of turns
SWG refers to wire thickness
mm refers to the diameter of the coils.
silvered means wires with silver coating, but it's not absolutely required, you may use super enameled copper wires as used in fan winding.
Sayad Hadia says
Dear swags,
Thank you for your good and distinct circuits.
How can I find the coils & and how can I use the transmitter without reciver
Regards
Swagatam says
Dear Sayad,
the coil are hand wound using the indicated copper wire sizes.
the transmitter signal can be heard over any standard FM radio with bands between 88MHz and 108Mhz
Anonymous says
Dear Swagatam
The communication will be heard by others having an FM band radio in the area. Is it any way that it can be mixed up with some harmonics/ noice and receiver can filter that specified harmonics/ noise (encrypt/ decrypt) so outsider may only hear noise while actual couple may chat easily.
Regards
Sam
Swagatam says
Dear Sam,
mixing up with harmonics would make it complicated, a simpler way would be to tune the FM transmitter on frequencies out of the normal FM band, that is either somewhere above 108MHz or below 88MHz….
Regards.
Anonymous says
Frequencies starting from 108MHz and up to 118MHz are used for aviation navigation (and above 118MHz for aviation communications). Never transmit to these frequencies, or by poor visibility an aircraft may crash over your head…
And below 88MHz you will be chating with the firefighters or the police…
princekumar gupta says
Can I use 2.4ghz for remote