TV transmitter circuit

Description.
The TV transmitter circuit given here uses UK standard 1 FM modulation for sound and PAL for video modulation. The audio signal to be modulated is pre-amplified using the transistor Q1 and associated components. The transistor Q2 has two jobs: production of carrier frequency and modulation. The pre-amplified audio signal is fed to the base of transistor Q2 for modulation. Capacitor C5 and inductor L1 forms the tank circuit which is responsible for producing the carrier frequency. The video signal is fed to the emitter of transistor Q2 via POT R7 for modulation. The modulated composite signal (audio+video) is transmitted by the antenna A1. This TV transmitter circuit can be operated from 12V DC. Either a 12V DC power supply or a battery can be used for the purpose, using a battery will surely reduce noise and improve the performance. If you are going with a DC power supply, then it must be well regulated and free of  noise.

Circuit diagram with Parts list.

tv-transmitter-circuit

Notes.

  • Assemble the circuit on a good quality PCB.
  • Inductor L1 can be made by making 4 turns of 24SWG enameled copper wire on a 6mm dia: plastic former.
  • T1 can be a radio frequency transformer with built in capacitor. (Can be found on old transistor radio boards).
  • Antenna A1 can be a 1M long copper wire. (Experiment with the length to get optimum performance).
  • This transmitter is working in VHF band somewhat between 50 – 210MHz.
  • This transmitter is compatible only with PAL B and PAL G systems.
  • Slight adjustments are required on the value of C8 for getting optimum performance.
Show Comments

138 thoughts on “TV transmitter circuit

  1. mnasim31

    Setharaman Jee, I am trying to make an UHF tv transmitter for which I have already found the circuit for video & it is working. Now for audio can I use the audio portion of your circuit i.e. upto c4 for the UHF transmitter? Also do I need any re-arrangement of circuit etc. Please reply me at your convenient. Thanks. This is the second time I am approaching you. Please reply.

    Reply
  2. mnasim31

    Setharaman Jee, I am trying to make an UHF tv transmitter for which I have already found the circuit for video. Now for audio can I use the audio portion of your circuit i.e. upto c4 for the UHF transmitter? Also do I need any trimming etc. Please reply me at your convenient. Thanks.

    Reply
  3. Abuyi M. J

    This is realy a cool site to me, Many thanks to the initiators of Circuit to day. This site can greatly improve and enable any student or researcher in the field of communication to be able to explore electronics communications to the depth. GOD bless you sir/ madam.

    Reply
  4. umakant

    ABOUT WORKING: Normally we connect one end of tank circuit(in this case collpits oscillator) directly to base of the BJT for providing positive feedback but here it has been connected to emitter . The reason is that at VHF frequency the base emitter capacitance,Cje, will act as short circuit. So it is equivalent to connecting directly to base.

    Reply
  5. muhammad

    Hi sir. I have RF modulator with 90db made for CATV. Where should I connect the output into the circuit? My purpose is to transmit video around 1km. Any transistor need to be changed? Thanks before.

    Reply
    • Pat

      Just connect it up to a Grid wide band Antenna it has an open dipole it does the job i have one working over 2Km at my cow shed, use same type Antenna to receive other end

      Reply
        • Seetharaman

          Hi Saad Please see reply dated 5th Jan 2014 of Mr. Prince.
          Hi Muhammad CATV amplifier are for boosting the signal in cable TV to 1volt pk signal. you can not use it as an RF amplifier to drive an antenna for which you require a RF power amplifier.

          Reply
    • Seetharaman

      Ensure the web cam is capable 1 volt pk video information if less add a suitable amplifier between camera and video input. you can use a carbon micro phone with suitable pre amplifier to produce an audio input of at least 1volt at the audio input socket.

      Reply
      • prince

        please which amplifier can I use if I can build it please help me with the diagram for the web camera n carbon microphone

        Reply
  6. virender

    Dear Seetharaman, I want your help in making Automatic Room Light using AT89C51 Microcontroller. I assembled the circuit based on two ir sensor, two ic 555 and two visitor counters. Every parts is ok but the circuit is not working. I do not know how to use source code. I never worked with microcontroller. But I want to make Automatic Room Light controller. Can you help in this regard please! With thanks!

    Reply
  7. sata2012

    Hi all,
    Who built this circuit?
    Which parts of the circuit should be changed to optimize the output?
    To increase the frequency to 500 MHz, what parts should be replaced and what elements should be?
    Please answer.
    Thank you very much

    Reply
    • umakant

      I realized the circuit but got very poor results. I would suggest you to try some different circuit or maybe purchase a RF converter kit and do reverse engineering.This circuit will not give optimum results without a RF amplifier{not tested).Anyway why go in UHF range? it will only complicate matters of impedance matching and antenna interfacing.And if you are short on time(I was), purchase a wireless camera online at robokits.co.in.

      Reply
      • virender

        Dear Umakant, I have not enough knowledge in electronics. But I will definitely tell you what I did in this project. I simply made this circuit without audio as given above because I did not find T1 (IFT) so I connect the simple FM Transmitter with it. But still I did not test it with audio but the transmitted video is very clear. I removed the trimmer C5 and using the fm gang condenser to tune it easily. And, I took the copper wire from the cable TV coming out from the house and wind it four turn on telescopic antenna of the codeless phone. I also changed R5, R6 with 1K and using Nokia cell phone charger. I hope this will help you. I am sorry for the poor English.

        Reply
    • Seetharaman

      Hi Sata increasing the space between winding will increase the transmitting frequency (and also by reducing the value of C5)

      Reply
  8. umakant

    hi, is c8 27 pf or 2.7pF?
    I did with 27pF and i m getting extremely poor,unstable picture.Please reply soon.will air former for l1 cause huge losses?

    Reply
    • Seetharaman

      Hi Umakant L1 is self supporting air core coil. you can wind it on a pencil slide out and use it. the windings are close wound. latter for tuning you can expand the winding little(small gap between each winding). C5 you can use oscillator section of PVC2X.(around 45PF) C8 can be anything between 2.2 to 27PF. Alternately you can connect Antenna directly to L1 tap at 1/2 turn from supply end.

      Reply
  9. virender

    Dear Seetharaman, I build this TV transmitter circuit. But the video is not stable and the screen goes up and down. I tried to control it using the V-hold control of my TV but the result is same. Please help to solve this problem. And also please tell me how I can increase its video quality. With thanks in advance!

    Reply
    • Seetharaman

      Dear Virender First check your power supply is of good quality with least ripple. if your power pack is ok, you may be over modulating, you may correct it by adjusting the video modulation control R7. This should solve your problem.

      Reply
  10. dananjaya

    hello sir,
    i like to make this but i know more…
    so, plz tell what transformer (t1) needed for this sellers ask for what transformer what is that tranformer if cannot buy it in marcket plz tell me what can i use for it?

    thanks.

    Reply
  11. virender

    Dear Seetharaman, Can you please help me in receiving cable tv signal video wirlessly on Laptop with usb fm stick (tv tuner). And also please send me the related circuit. Any reply shall be highly appreciated. With thanks!

    Reply
    • seetharaman

      Hi Virender That cannot not be done. you cannot modulate the entire band of signals with a single modulator.

      Reply
  12. deni purwanto

    excuse me sir,,,
    where can I get the pc board and components of this circuit?
    I’m from west Kalimantan,
    thanks…

    Reply
    • Ben Smith

      If you were to link the output of the board to two (2) FM booster circuits in series with each other, then you can output up to around 3 miles.

      Reply
  13. Sylvain

    I just released this circuit but audio part is not running, advice me what to do because i lost required frequency transformer, can i released other audio circuit and combine them after? if ok, tell me how to find that circuit. Thx!!!! still waiting ur best answer

    Reply
  14. John

    i already released his circuit but is running but pictures are not stable and sound is not being received or transmitted what are the solutions to resolve this problem please advice me what to do.

    Reply
  15. Bosco

    hi! i already released this circuit but is not running i thing the problem is final oscillator capacitor and coil if possible sent to me images of coil to be used is it air follow or it has other material inside? plse help me

    Reply
  16. seetharaman

    Hi Sylvain the final oscillator imedance will get affected you may have to change capactors, hence follow the given circuit

    Reply
  17. Sylvain

    please help me by sending power amplifier of 20watts that i can use to transmit up to 10km until now i am still searching but not find or send to me a precise link thx!!!

    Reply
  18. Sylvain

    1.i visited all given links but i need that you precise which circuit can i use to transmit up to 10km,or send it through my e-mail if u have (bivain2020@yahoo.fr)

    2.Now the circuit is running at short i need to improve how can i send my name in so that it can be received with transmitted video on top of tv receiver,try to send to me a circuit

    Reply
  19. seetharaman

    Hi Gerald check you power supply for regulation. check for your modulation level it may be too high. finally if transmitter drifts when your hand is close to antenna reduce C8 to 2.7 to 4.7 PF.

    Reply
  20. gerald

    i built this cicuit and it worked out but the frequency was going on and off. what could be the problem please help me. dont mind my english.

    Reply
  21. Sylvain

    Hi Hi!!!!! In my country is not illegal, so advice me amplifier to use by sending precise link where i can find it because sent link i find many and i miss how to choose which one is compatible, is helpful i you send a full circuit i can use, thanks

    Reply
  22. Sylvain

    help me by sending circuit that can used as tunable amplifier of 20to30watts through my e-mail,thanks!!

    Reply
  23. seetharaman

    Hi Sylvain you have to use high power RF Transistor in class C mode with tank and aerial tuning unit after Q2 and tune it with SWR meter etc. it is not under the purview of this article. you require licence etc.

    Reply
  24. Sylvain

    Tell me more about amplifier, can i use audio amplifier of 30watts made with TDA2040 with frequency limit of 100khz you presented in audio amplifier? pleas help me i need to implement this 10km tv transmitter, thanks!

    Reply
  25. Sylvain

    what are the requirements to release the circuit said to operate up to 10km? any modification to the circuit presented or only addition tunable amplifier is added? transistor used are BC547 or 2N2219? whit type of antenna used to this circuit?

    Reply
  26. Seetharaman

    Hi Sylvain All capacitors can be rated for a minimum of 16 volt. Standard video signal maximum of 4MHZ.

    Reply
  27. Seetharaman

    Hi Sylvain C1 10 & 12 are electrolytic. C5 is variable capacitor (trimmer capacitor) all other capacitors are ceramic disc type. (you can use Philips Pin up or ceramic tubular capacitors also)

    Reply
  28. Sylvain

    here c1,c2,c3,c7,c9 are which type of capacitors,is it ceramic or electrolytic?? please help me!! is very needed.
    thx

    Reply
  29. Sylvain

    i need to know more details about capacitors used in this tv transmitter each with its relative voltage rate examples c1=10uf/16volts thx

    Reply
  30. AVDI

    HI
    who can explain me about this tv transmitter,what parts is T1,,is transformer or what part,what i can replace with T1, how far is range for this TV transmitter..THANKS

    Reply
  31. gnanendra

    hello sir
    i want to make a video transmitter circuit and a receiver for my project would u help me in giving the basic idea and how to proceed..?
    sir
    basically i want to know everything of each component so please send me data sheets or ref sites
    thank u sir

    Reply
  32. Sadik

    I made this Circute but it is not working good, I have a doubt in Power using, how many Ampier we can use. I used a Regulated IC 7812, I don’t know how many ampere use please help me in problem,

    Reply
  33. hb

    hello seetharaman…. first of all i am a fan of u and of circuitstoday…no better website than this for hobby projects….main thing is u people are responsive to requests and i also u dont steal circuits and post them blindly but you work them out,and study them before posting,u are doing a real great work.

    i would like to know that if it is possible to transmit comp usb data via any digital modulator circuit over the air and get it received by demodulator…i dont ask for any high speed lan type of performance but even simple hyperterminal would do…or maybe atleast ability to transfer data between two pcs but by our own made diy circuit…and how much challenging it would be..
    thankyou
    hb

    Reply
  34. Avdi

    HI Seetharaman THANKS
    Can eplanin me more about,ceramic capacitor disc,UF ,PF,N i dont know which is big size,or big voltage,,,i see ceranic disc have 3 kind color ,,red .green.blu..same example here,B103K, B472K.B181,,151J,,681J.,i cant understand about this,how i can chack part is good or bed,what kind multimeter,can chack,ceramic disc.
    I dont know for size of rasistor,which is big [K] or [OHM] or [M] i need to learn more,i just start to learn.
    THANKS

    Reply
  35. Seetharaman

    Hi Avdi for ceramic disc capacitors there is no polarity. there metal discs and ceramic insulatotors are stacked alternatly. they are not wound hence no inductive component involved,due to which they are most suitable for high frequency circuits. but they are available in low values upto 2uF votage from 12 to few kV. normally text will be on one side and the other side will be blank. same resistance code type but written in numerals. say 104 means 10 X 10 to the power four PF. 101 means 10 X 10 to the power 1. that is 100PF etc.

    Reply
  36. Avdi

    Hi can sameone from you,can explain to me,,about ceramic disc,,i dont know ceramic disc ,which side is + -or thet is go which side have text on it.
    THANKS

    Reply
  37. Seetharaman

    Hi German Connect C4 to ground instead of audio modulation transformer T1
    The circuit from audio in to R4(incl) not required.

    Reply
  38. seetharaman

    Hi Sarvesh In 180deg you will have 2 lugs these are conected internally and to be connected to supply and the single lug between them is the variable plate should be connected to Q2 collector

    Reply
  39. sarvesh

    i m having difficulty in connecting capacitor “C5″ .
    This variable capacitor is actually having 3 legs. & in circuit diagram it is shown with 2 legs only . So plz explain me , how to connect these 3 leg capacitor “C5″ in the circuit.

    Reply
  40. NASEEF.KK

    pls help,i want to connect the AV cable of DVD to my PC. i got a AV to USB cable from market.but cannot watch it.
    it want any driver softwear? help me

    Reply
  41. NASEEF.KK

    i cannot get 2N2219 transister any where.pls advise other same value transister.how create power amplifier with tuned circuits? pls send the circuit diagram.
    pls look to circuit as Capsitor 3,11,12.it’s other leg where to be connect? it is free ? or it is earth?

    Reply
  42. dedi

    sir,

    is the BC547 very high frequency transistor ?

    because i often use this transistor as a switching transistor. This transistor is a cheap transistor. Can i use this transistor to build oscillator in radio circuits.

    sorry, my english isn’t good

    thanks

    Reply
  43. seetharaman

    Hi Naseef it is an RF power amplifier with tuned circuits. You can use any good RF amplifier with say 20Watts RF output for your project. i dont have one check in the net

    Reply
  44. Naseef.kk

    sir,
    what is tuned power amplifiers ? how create it?
    can i buy from electronic shop? how add tuned power amplifiers from the collector of Q2?
    i expect your valuable reply

    Reply
  45. seetharaman

    Hi Naseef We are not supposed to radiate signal beyond our compound, beyond this is illegal in most of the countries.
    By increasing power you can achieve better range, less noise and better clarity.
    By increasing frequency nothing can happen to range.
    A vertical whip antenna is to be of one forth the wavelength. This is antenna theory a small fine tuning is required to improve the radiated power.
    You can also use two folded dipoles one above other at right angle with the transmitter, To have a coverage of figure of eight.

    Reply
  46. Naseef.kk

    sir,

    “(wavelenth of the frequency divided by 4). to optimise the output radiated power.”

    pls describe above line,as it is your statement.

    Reply
  47. Naseef.kk

    sir,
    thanks,
    1.when i rise circuit frequency to wide area,will get full clarity in vedio and audio?
    2.how much KM distance we can rise maximum?
    3.any illegal problems for the TV transmitter by POlice or Govt

    Reply
  48. seetharaman

    Hi Naseef Try by replacing Q2 with 2N2219 change R5 and R6 to 10K and emitter resistance of Q2 1K pot to 100 ohms carbon pot. use a 1.5 meter telescopic whip antenna try by varying it length (wavelenth of the frequency divided by 4). to optimise the output radiated power.

    Reply
  49. seetharaman

    Hi Daniel you can use any PAL set you can tune the oscillator to cover old turret tuner’s Ch 2 to Ch 12. Band I ch 2 to 4
    and Band III ch 5 to 12. T1 can be SW 5 pin oscillator coil or old sound card input transformer 5.5MHz or FM IFT with additional capacitor to tune to 5.5MHz.

    Reply
  50. nara

    John! In old transistor radio board I found there are couple of T1 type radio frequency transformer. Could you specify which one of them, red, yellow, white, as these IFT transformer have different capacitor value

    thanks

    Reply
  51. daniel

    I want to know if this can be receive by an ordinary tv set, and on what channel? so it won/t work on NTSC system?

    Thanks

    Reply
  52. seetharaman

    Hi Rajesh use a pocket FM radio with TV sound to check the frequency, or directly connecting it to your tv and search tuning it and get the frequency.
    Hi Govind Chinese make simple pin hole camera without flash for 35mm film is available for less than IR100.00 in the market. Tell me your specs. i will advice.
    Hi Raj you can use Solar photo voltaic cells, wind power generator, hand crank generator(have you seen the latest philips LED torch light with hand crank charger-environment friendly). You may fit dynamos to all these fintness centres, the human energy wasted there can be utilised in a better way – hey not joking i am serious about it – do you remember GD Naidu has done it for watering his garden)
    Hi Farrukh the video input can be from you vcd player or from video camera or from any video source. any tv set can be used.

    Reply
  53. Farrukh

    can u plz tell me the input from video side?
    and also the circuit for receiver or any other easily available circuit which could be used?

    Reply
  54. Seetharaman

    Dear Murugan you can use any camera with an analog video out put signal of around 1 volt peak. lighting level for the object and modulation level pot R7 you have to adjust to suit your requirement. Best wishes

    Reply
  55. niloy

    Hi i need a serious help from u, how can i use usb cam (which I use in PC) as an option with this circuit? Is that possible? kindly reply,

    Reply
  56. murugan

    what camera is suitable..
    i need a cheap and affordable micro camera. can i use micro cam…
    pls help.. tnx
    mail me

    Reply
    • admin

      the range of this TV transmitter circuit is around 50-60 Meters.
      this is only a hobby circuit and is not meant for any serious application

      Reply
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  60. twits4twats

    1 desmond says:

    July 9th, 2009 at 8:07 am
    all these components are not common in Ghana, so how can i get some?

    Hi Desmond

    Email these two companies and ask if they will ship to Ghana from the UK.
    rapidonline.com
    uk.farnell.com

    I think you will be plesently surprised.
    As a suggestion, have you tried looking in old TV’s and radio’s?

    Reply
    • admin

      BF494 is a medium power ,radio frequency transistor.In most cases it can be substituted with transistors like BC547, BC107, 2N2222 with a little compromise on performance

      Reply
    • admin

      All components used here are extremely common and they are available everywhere.
      BC547 can be substituted with BC107, BC548,2N2222 etc.

      Still problems?? Then comment here.I will help you.

      Reply

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