How to build a 2 transistor FM transmitter.Long and short range.
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- Опубликовано: 14 окт 2024
- See our 1 mile UHF transmitter at:
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Lets make a very simple 2 transistor FM transmitter
In this video i will show you how to make a
FM Transmitter that is very easy to build and get working.
Frequency: 90Mhz - 108Mhz
Current consumption: 15mA at 9v
Working Voltage: 3v - 12v ,more Voltage more transmission range !
Stability: Not bad
Transmission range: Antenna 20.6cm= 100ft - Antenna 165cm= 800ft+ , Penetrates through walls and ceilings.
RF Power: about 8mW RF output
PLEASE NOTE
The videos I make take a lot of time to film and edit ,I know I don't make many videos and that I will improve on in the future ,any donations are welcome to my PayPal account at: dazaro@blueyonder.co.uk
Thanks
Parts List:
R1 Resistor: 47k
R2 Resistor: 1M
R3 Resistor: 10k
R4 Resistor: 47k
R5 Resistor: 470R
C1 Capacitor: 100n
C2 Capacitor: 100n
C3 Capacitor: 1n
C4 Capacitor: 33pf
C5 Capacitor: 10pf
C6 Capacitor: 10pf
C7 Capacitor: 100n
Homemade PCB
Ceramic trimmer capacitor ,5.2 -30pf
10mm Microphone
2n3904 transistor x 2
Antenna wire: 12.6cm wire ,or 165cm for more transmission range.
L1 Coil 5 turn
PP3 battery clip
Thank you so much for making these videos. You have a way of making the most complicated things look so simple and accessible to anyone.
I've never made a PCB so I used Veroboard, and apart from some distortion with louder sounds it works great. Thanks for the video.
Good to see the step by step guide start to finish. And it's something my young bloke will watch. As he always says. If i want to know something I'll watch RUclips. Except when he wants me to do it
Your video is the first and only that I have seen to explain and show from start to finish how to build a transmitter. Have you done a transmitter and receiver? Well done!
Now I have a couple of questions for you:
1) On which side do you tap the first coil of if you plan to increase stability? The side of the positive rail or the one at the collector side of the transistor?
2) In that case of tapping of, would you still recommend to add a 10p capacitator buffer stage to prevent the antenna from feeding voltage back into the tank circuit?
4) Compared to your earlier videos, I noticed you had changed all the 22n to 100n. Why? What is the improvement of C1 and C7?
5) Why is C2 sometimes an electrolytic capacitator, even with higher capacitance, but here its just a 100n ceramic?
6) How does R5 influence output power, battery life time, etc.?
7) The internal load resistor R1, what is a good value for it in regard of different operation voltages? I noticed if you have only a 3V source you need lets say 22k, but for 9V 68k is better or otherwise the mic will be overamplified to much. In that case, wouldnt a variable resistor be advisable?
Collector side.
Those brings back a lot of my childhood memories. :)
Many thanks Pal. Just made one using Copper Clad Board, stable and crystal clear. House it inside a Tuna Tin Can. Noticed that most of the Single Transistor based Bug frequency drift pretty easily, esp using MPSA06 or 2SD965 NPN. no luck at all.
To make the FM transmitter much more stable but a bit less
transmission range you can tap the antenna from the
transistor emitter and not the transistors highly sensitive collector,
or add a buffer\amplifier transistor after the oscillator transistor.
Darren is right + you can tap a coil 1 turn above collector and solder antenna to that. Or check out TE website, really great explanations www.talkingelectronics.com/projects/Spy%20Circuits/SpyCircuits-1.html
Scroll down as you progress
Hi Dazaro3, Nice circuit board and build of FM TX. The 2N3904, NPN transistor does work extremely well. I love building FM transmitters. I usually just use a fixed capacitor of around 27 + or - in the tank circuit. I have variable caps but don't use that often. I sometimes tap my antenna to the 2nd turn of the coil and have even connected to the emitter side, and, seems to work good. Take care, C.
And dude. Thank you for explaining each component. Great vid, buddy. Thank you
Dazaro3 I always enjoy your videos! I remember the first time I built a Tx from scratch,powered it up I just couldn't believe it worked (I taught myself electronics ) but from then on I was hooked, if only I had your videos back then sure would have made things less frustrating -I almost gave up! so like everyone has said keep up the good work
Hey Darren, the sound on my bug always has sizzling effect, yet your transmission is crystal clear, why is that. Thanks.
very cool indeed.. oh ye ,,, in the 70s my friends also built all kind of circuit..
I remember they were so excited when the amateur magazing brought the dolby a and later the b ... they immediately built one.. but me... I never got the spirit really :-) good to see this spirit alive yet..
keep up with your good work
As always nicely done sir. I was wondering, how about audio and video transmitters or TV transmitters??
Hello sir, thank you i follow you always and watching your videos changed my life, recently a question created for me that, what is the GND or grounding in portable devices such radio, walkie talkie, rdio transmitter and mobile phone??
especially in this radio transmitter circuit which you have made!!!
Come on Darren I am getting ichy fingers waiting for the next transmitter.Have a nice christmas.
Hi Darren! Thank you very much, the circuit is awesome. I just built it, but it is extremely sensitive. If I whisper the sound is perfect, but if I talk loud, it distorts a lot. I checked my connections and parts and it seems to be right. Any thoughts on this? Thank you very much again!
fredi, tenta aumentar o valor do resistor do microphone que deve melhora isso
Reduce gaib
Thumbs up for new editing and music. No offense, but old one was a lil' bit pessimistic, so, good job on this one.
You are the man .your excellence of work is second to none
Is it possible to substitute a 3.5mm jack for the mic?
Yes...and it works fine
Amazing video!! Congratulation mr. Dazaro!! I will try to make this transmitter..
cheers Daz
,,for taking the time m8
Where can I purchase one of the table saws that you use. Thanks !
Fine video, Could you tell me more precisely the maximum range?
another good clear video D.P. one question regarding antenna. does the 165cm have to be extended or can it be coiled to save space? cheers
Yes it can be coiled ,but then you will have less transmission range.
dazaro3 thank you for viduos may name is hassan rasool from baghdad.iraq.
Nice work mate. I love these videos!
Keep em' coming
Another good one for the books, I’m gonna build this one as well with a nice electric blue acrylic case, after watching a lot of your videos , using the spoken word as a test transmission instead of music (I understand why) could you not use some copyright free tunes like in the end titles of your videos. Or get a friend to compose a Dazaro3 Theme tune for radio testing.😁👍🏼. Job well done. Barnie.
Hello, great work thnzk you !!
how I could calculated the transmission distance ?
Right...after christmas....we will able to see your next project then....It will be perfect to make one receiver for this transmitters..
can i also build that onto a normal circuit board in a different order?
I am wondering does the antena wire has to be exactly 20.6 cm ( or close to that) for transmiter to work. Will it work if its not 20.6 but something like 13 or whatever cm ?
I just built this ground plane style on copper clad board and with an antenna of 18 gauge wire i can transmit a thousand feet with 26.6cm antenna length. Stable and crystal clear. Trimmer cap o 2.8 to 20 pf and that covers every frequency in that band. There are lots of harmonics, but once i got the frequencies exactly the same it was clear as a bell. I broke out the LC take with the coil and cap onto two rails of 18 gauge wire because my circuit got really crowded but it effects nothing at all. You can drop the board to the ground from a few inches and the frequency wont wobble at all. Great little thing. I am putting an audio jack on it too with a switch to toggle between microphone and and audio jack. This is plenty clear and stable enough to provide good entertainment on the road. And strong enough that you will get no interference. IF ANYONE NEEDS A WORKING GROUND PLANE SCHEMATIC OF THIS CONTACT ME.
Hey I would like your ground plane schematic please :-)
Colton Booth
You can download from under where is says "more info"
Could i get a copy of the circuit diagram? it would be much appreciated, Thank you.
Could you please send me the schematics for the circuit. The one that you said you are going to create.
Can you send me a copy. That would be great.
PCB print not found... Please upload the image again. Thanks
And so you were saying thise transistors are the best foe this project? Or would you recommend any others?
And would a change in coil turns make anu dofference? If so. What differences?
@dazaro3 - What software do you use to design circuits? Love your videos and I subscribed. Thanks. :)
Its eagle cad I think. 🤔
Are the resistors positioned standing for interference, or just saving board space? I can see this getting reduced with SM parts...
PCB print file on Filedropper doesn't exist anymore. Can you please re-upload the PCB print? Thanks.
the schematic and pcb is on the video copy it off there
Greetings, I tried to download the link but it wants me to sign up for a buck a month, not intrested enough to pay that much for it. Wouldn't mind having the diagram for the PCB if you happen to get a chance to link to it somewhere free?
I want to replace the Microphone with a stereo (for guitar input) input audio jack. Do I have to make changes in the circuit or I can simply replace the mic by the jack?
hey sir. we don't have any available 30pf ceramic trimmer capacitor here, what should i do ? or is their any option?
Very good work
Very clear work
How much distance (meter)
can i use this transmitter as a walkie talkie ,i mean that can we move it will the signal be stable or should we keep it unattended in a place
how i can add audio output for recording voice to mp3 player ?? i am waiting for your reply .
Always enjoy your videos. Great job.
I was making these 20 years ago!
can you also change the frequence by adjusting the adjustable capacitator? Thanks and nice video!
+Y Channel
That is how you change the frequency by the adjustable capacitor or stretching or compressing the 5 turn coil
+dazaro3 thanks for your answer so just try and see right?
HI DAZARO , I AM TRYING TO PRINT THIS CIRCUIT USING LASER PRINTER BUT IT KEEPS ON PRINTING FULL A4 SIZE PAPER .CAN YOU PLEASE GIVE ME A LINK TO DOWNLOAD THE IMAGE IN ITS ACTUAL SIZE (35MM X 22MM) OF THE PCB .
hi dazaro3, thanks by sharing your knowledge! can you say me please the gauge of the antenna wire? it's awg23? awg24? or awg25? thanks!
+mendokusenaaa
Any will work just fine.
hiya there. do you have videos on how to make a wireless camera transmitor? Can you do a video on how to make a camera and audio transmit or? also, I want to be able to plug it in to the wall, is that possible?
what kind of chloride did he used, the green liquid in inside the glass and how many percent of acids itself? where can i buy it? thank you
Its called ferric chloride acid and most of the time its brown ish but since he used it for so long its green. I got a large bottle of it from a company called MG chemicals
Which software you used for creating the circuit diagram?? can you please share it??
I use diptrace
Thanks for your reply.
Is it possible to do simulation on this software??
will you plz post a fm transmitter booster. i need some thing to amplify the output to gain a higher range up to 2km (3mile). thanks. bye the way i made the world smallest fm transmitter (on this channle i found) and it works fantastic it transmits over 20m without antena!!
can you please give me the link to download file from pcb layout for printing?
Thanks :]
Hi Dazaro.
I really need some help right now!
I did this whole thing yesterday and it really worked ! and the audio is very clear.
But when I changed the antenna to a longer one and glued the battery connector under the pcb, the whole circuit didn't even worked anymore.
I have tried many troubleshooting already but still it doesn't work.
Things I have done already.
- change the antenna (3 x already)
- change the mic (I only have a very small extra mic that came from a headphone. )
- fix every soldering
------------------
- the battery connector didn't touched the pcb soldering when I glued it.
- I can hear the sound is changing when I adjust the trimmer capacitor. (but there's still no audio)
I don't know what to do anymore. I NEED TO PASS THIS ON MONDAY MORNING :(
What can be the problem ?
Will the circuit be ruined / broken when the polarity is changed ???
I only tried it with a 9v battery and a 12 v lipo battery.
PLEASE HELP SIR!
And also.
I'm using 4 mylar capacitors rather than all ceramic (because there's no ceramic capacitor that has that value).
Please help Master!
please. :'(
Instead of 33pF can I use a 30pF ??? Also, I salvage my components and cannot find any trim caps, will a 10pF or 15pF ceramic cap work instead???
TheNewtonsapple Yes 30pf will be fine,and you can use a 10 or 15pf in place of the trim cap.
I used a 10pf instead of a trim cap. I must say this is an excellent design. I even built another using rca audio plugs instead of the headphone plug, works well.
what material u use to make the coil and where can i find the material.
Cara eu gostei daquele programa de computador que ele usa para impressão dos circuitos alguém sabe o nome?
@dazaro3 - I ordered a FM transmitter DIY kit on 25 Mar '18 and it has been 21 days and counting. UPDATE - fast forward I received it today 20 Apr '18. Apology is accepted and thanks for the free gift. :)
John Piper
So sorry John , your FM transmitter kit is on its way to you with a free gift ,we have 1000s of happy buyer's of our kits/transmitters,please accept our apologies.
***Hi @dazaro3 - Derryl*** I will update my initial entry above after receiving my order. Apology is accepted. Thanks. :)
very good video dazaro how range this circuit
Super! working ! Thank you!
Hi dazaro3, I've tried to make this four times now but its never worked. Do you have to use carbon resistors as opposed to metal film ones?
When building FM transmitters you need to have all the soldering work 100% because
they are high frequency circuits ,if a transmitter is working at 100Mhz they are working
at 100 million cycles per second ! so all parts need to be in the right place and all
soldering work 100%.If its build right it will work.
Hope the above helps
Can I try the circuit on bread board at the initial stage will it work?
With Diptrace do you run the auto router or do you route manually ?
I did it manually.
what pcb software would you recommend for a beginner.
eastenderaz1
DipTrace - PCB Design software, its very easy to use,its the only one i have used.
Its called ferric chloride, you can get it on ebay, the technique works very well.
Could you use a Fractal Antennae?
.....RVM45
agaiiin.....
can you send me the link that has the pcb lay out pleeeeeeeeeease dazaro3
How to increase transmission range in the circuit? Which componen add or changing value?
I want to learn this fm bugger circuit...please let me know about its fabrication...
Is possible a stereo fm transmiter with transistors? i just have seen with a IC BA1404, but the power is definitaly less than the monoaural transistor version and the xtal that use the circuit (38khz) is almost impossible to buy.
Just for experiment would be fun
+fersunk
You can not build a stereo transmitter using this method.To build a stereo transmitter is so much more complicated,
you will need a IC like a BH1471 or a SN761634 and many more. A BA1404 is very low on RF power ,but you can add a RF amplifier stage for more RF power.
dazaro3 yeah I got it, so basically I need something with more power or an amplifier stage but this would add noise :/
fersunk
There are at least 3 of us looking for the pcb layout. I want to build this but have had mixed results with materials other than pcb. The file for the pcb is not working, maybe use dropbox instead.
Can you do a tutorial for building a fm radio??
+dazaro3 I have the same Gooit frequency counter you have and I notice my signal fluctuates an awful lot from 92.1 - 93.1. I tried different frequencies but cant keep it stable, it moves up to 2 MHz for no apparent reason at all. I made the circuit using your pcb schematic after having the same problem with bread boards. the only difference between yours and mine from what I can tell is that i am using a 10-40 trimmer capacitor (yellow), 24 gauge for the coil and my resistors are 5 band 1 percent tolerance. Any recommendation on how to make it more stable?
+Juan Villicana
It may be the transistor you are using , if you can try different transistors. To make the FM Transmitter much more stable connect the antenna to the emitter on the transistor not the collector side , and keep away from
transmitter when using it. Try a 165cm wire antenna
+dazaro3 I'll try your Antena recomendación. I already tried a diferent brand of 3904 but I have not tried my 2222 transistor so I'll try that as well. thank you for the videos and reply.
+dazaro3 so I tested and it was a combination of the frequency counter showing different frequencies depending on where i put the antenna. lower signal was giving me a higher frequency and full signal was giving me the correct frequency with minimal fluctuations. The length of antenna was the biggest issue, as I live in an area with a lot of Antennas and in turn a lot of radio stations making my transmitter fight for the frequency.
I didn't notice this before because my radio is a cheap digital pocket one and you cant find tune the station to an unused one.
once I added the 165 cm antenna it was able to maintain a signal. I Also I added the longer antenna to my 3v transmitter that i made from your other video and it worked great.
Thanks for the help.
On the website it says don't order if we live in UK or EU?????? How do we order them?
Nice one ... good clear videos. Thanks, realy enjoy your vids
Amazing 😯👌👆🙏
Can I use polyester capacitors instead of ceramic? Please reply
Please replyy :(
T Ξ S L Π Ceramic capacitors are the best for HF so I wouldnt recommend polyester
Great stuff Daz.
would a circuit like this still transmit if i replaced the mic with a 3.5 mm female audio jack
+railfan225
Please see my other videos where i make FM transmitters using a audio input
Great design. I can't ge the circuit diagam to load. Help Please.
What program do you use to design your PCB layouts?
riddick1125
I used Diptrace
Cara muito bom seus vídeos.
Mais al quem poderia traduzir pra min
Qual é o nome desta química que você usa nas confeção da placa?
Percloreto de ferro
Fredi Machado .NET
Valeu cara muito obrigado.
Sera que é fácil de de encontrar?
jesse alves pereira Em loja de eletrônica normalmente se encontra.
+jesse alves pereira olha esses links do mercado livre, e de percloreto de ferro, facil de adquirir produto.mercadolivre.com.br/MLB-736242389-frete-gratis-percloreto-de-ferro-500ml-liquido-_JM e produto.mercadolivre.com.br/MLB-736238545-percloreto-de-ferro-500-ml-liquido-_JM
hi dazaro...can u plz explain the circuit??becoz i have to give viva on it!!
Can i use a 3.5 mm audio jack instead of mic??
Thank you very much, it work yeeeeeeeaaa :)
Is there a formula that will give the frequency?
Mr dazaro instead of a 2N3904 transistor can i use a bc547?
+Cristina Erotokritou
Yes ,You can use\ 2N2222, BC547 ,BC546 ,2N3904,2N4401 ,BC550 ,BF199 and many more low power NPN transistors.
Make sure there are NPN transistors and NOT PNP transistors.
tested on a breadboard ;
i made it, it works realy good, but the frequency is not stabe if the antenna length changes.
at which frequency did it transmit ??? pls reply asap wanna try this on breadboard
p.s did u use 2N3904 or other?
Love this! Thanks! You are a genius!
Muy interesantes proyectos de transmisores de f.m mostrar diagramas picturicos y esquemático y listas de componentes con sus valores y como hacer las bobinas ayuda mucho. Un saludo para todos desde pavas costa rica.
Hello! Can I connect audio jacket to this?
Cho tôi xin link bản vẽ mạch đó được không
The language: vietnamese
I forgot to add the reason why I posted below lol (most of you probably already knew this) but if you use a 3mm machine screw (or what ever size screw you need for your coil) and lay the wire in the threads you end up with a perfectly round & evenly spaced coil, just unscrew the coil like a nut. I make all my coils like this & works really well just thought I would throw that out there
How many bits do you break???
Hello daz,when are you doing the next project .
New project within the next 2 weeks ,been very busy at work.
Ok great,Have a nice christmas.
what is the difference between a single and two transistor circuit?
+karan pandya
The FM transmitter with 2 transistors ,the first transistor on the left
is a microphone amplifier ,the extra transistor will give the electret microphone
more sensitivity.
Most 1 transistor FM circuits over-drive the microphone and this will create a lot more noise.
Hmm...ok..thanks
+dazaro3 my transmitter works well on 3v but i want to increase it range i tried it on 9v but it doesn't work on 9...why?
+Electronic Experiments sure..!!
@karan pandya - Is your transmitter the same circuit as video tutorial? Could be over biasing the transistor. The frequency could have changed too by changing voltage. Other possible reasons electronic components failure and or below tolerances etc. :)
Can i replace the mic with audio jack?
this 1 is working nice job
Sir u r great
very good tutorial sir thanks.
please upload a video helps us to make FM reciever.
All resistors are 1/4w or 1/8w?Thanks¡¡
PabloMMIX
1/4w or 1/8w will work fine
dazaro3 Thanks.
***** Thanks.