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Have you ever wanted to broadcast your own radio station within your neighborhood? Ever get curious on where people get those "Surveillance Bugs" from spy and action movies? This small and simple FM transmitter is the toy that geeks have always wanted.

FM transmitters can be complicated to build, that's why I'm teaching you how to make a foolproof FM transmitter. There's no need to buy kits, this tutorial includes the PCB layout and the schematics. It has a range of up to 1/4 mile or more. It's great for room monitoring, baby listening and nature research.

My Experience:

FM transmitters remind me of my early years in electronics. When I was 8, I came across Art Swan's FM transmitter circuit. At the time I had no idea of where I'm supposed to buy the parts, so I recycled mine out of junk. I guess the biggest struggle that you're going to face is finding a trimmer capacitor. I'll give some tips on the last step of this instructable. In a nutshell, I highly recommend this project for everyone and also those who are still new in electronics.

>>>>>>>WARNING: You may experience nostalgia! :D<<<<<<<

Technical Specifications:

- 1/4 Mile Radius Range

-Powered By A 9V Battery

- Lasts For Several Days

- Adjustable 87-108MHz

Please Watch: Celebrating the 1st episode of my new YouTube channel! It's my first time to document a project with videography. I hope you guys enjoy the vid! Please leave a comment below, I would appreciate some advise regarding the video.

Disclaimer: This project is for educational purposes only and is not intended to air/ interfere with present radio channels. Neither site nor I, am liable for careless actions. Please check for the legality before attempting the project within your area. As long as

Step 1: Gather the Parts

All of these are available on any branch of RadioShack! :)

______________________________

MISC:

- Copper Clad PCB/ Perfboard

- Solid Gauge # 18 Wire

- Electret Microphone

- ¼" Bolt

______________________________

Transistors:

- 2N3904 General NPN Transistor (2x)

______________________________

Capacitors:

- 15pF or 40pF Trimmer Capacitor

- 100nF Ceramic Capacitor (2x)

- 10nF Ceramic Capacitor

- 4pF Ceramic Capacitor

______________________________

Resistors:

- 1M Ohm ¼w Resistor

- 100K Ohm ¼w Resistor

- 10K Ohm ¼w Resistor (3x)

- 1K Ohm ¼w Resistor

- 100 Ohm ¼w Resistor

______________________________

Tools:

- A Pair Of Pliers

- Soldering Iron

- Hot Glue Gun

I connected the circuit as per circuit diagram but there is no any out put.what the input for the circuit and how much frequency range it is?
Thanks dude. Works great.
Pcb layout size of print what?
Sorry, I'm not sure what your question is exactly.
+255715255490 <br>Whatssap me
<p>im already done make the circuit but im still cannot get the frequency that i want..can u look my circuit if have mistake..tq</p>
<p>I found that getting a specified frequency given the author's proposed hardware setup is quite difficult. I end up getting whatever frequency is not broadcasting very strongly in my area. Just try scanning through all AM and FM frequencies and turning up the gain on your transmitter.</p>
<p>How does one turn up the gain on this transmitter ?</p>
<p>Increase the power supply voltage would be the quick and dirtiest way. A few others might be to change R2 and R3 to increase the bias voltage at the base of that transistor. Or maybe decrease R4. There are a few others, but again, it comes down to increasing the collector current of the transistors which would happen by change the collector resistance, increasing the base voltage/current, or by increasing the power supply voltage.</p>
<p>its working or not</p>
<p>It worked fine. I couldn't specify a transmit frequency, but I could pick up the signal on a few open channels.</p>
Would u sent me a breadboard circuit degin photo?
<p>I don't find 4pf ceramic capacitor </p>
<p>The schematic diagram included a 0.01pF Capacitor - which is not existent anywhere (unless probably its a DIY capacitor). This capacitor isn't included on the parts list so i guess its a mistake</p>
<p>Search for 10 nF</p>
<p>i couldnt find an 10nf capacitor in my area or the site buy components from</p>
<p>email me your address and I mail you a cpl</p>
<p>@gmail.com</p>
<p>0.01pF is not equal to 10nF... i'm guessing that 10nf (equals 0.01 microFarad) is in place for the 0.01pF.... - its probably a typo error</p>
<p>Ye but 10nf works for sure so just get that one :P</p>
<p>what you can do is twist two pieces of plastic coated insulated wire to make up your own cap to that value of 0.01pf</p><p>any advice anyone can contact me the expert</p>
<p>Probably so. I didn't see it anywhere either.</p>
Problem is I couldn't find a trimmer capacitor like you said but I found one with three terminals and a transperant shell. And i made it and ran it but there was no clear signal from transmitter but an interfierence signal from transmitter to radio with high pich noise. Any help guys?
<p>ill trade you a cpl for a circuit board</p>
<p>ebay, you can get like 10 for $4</p>
<p>cant I make this without the circuit board? Solder the components in order or on a few little bare copper wires? What is a good mic? A mic that's more sensitive?</p>
<p>Is it possible to make a similar thing with longer range? At least a mile</p>
Maybe you could attach a fritzing. It would help me a lot. Definitely building this!!! AWESOME!!!
Hello... somebody help in getting my transmitter correct... actually im able to transmit but the problem is I have to hold it in certain position or even if I keep the transmitter in one place I have to move my body or wave my hand to a place where im able to hear whistle sound... sounds funny but this is the problem im facing...
<p>Can I use 3,9 pF capacitor and 2W resistors ?</p>
<p>you can adda the caps in series if you havnt got correct values or put them in parallel to get the caps in 20% of the value you need or you can alter the windings on the coil either way its not set in stone you are basically altering the magnetic fild of the coil so if you mess about with values and changing parts you will learn how it is working properly instead of just copying someone elses circuit</p>
<p>Thanks a lot dude :)</p>
<p>I AM GOING TO BUILD THE CIRCUIT TOMORROW SO IF YOU WANT TO FOLLOW ME BUILDING IT I WILL LOAD MY VIDEO OVER THE NEXT 48 HOURS TO HELP ALL YOU YOUNG SCIENTISTS ANY QUESTIONS PLEASE ASK ME (harveyh7) ONE OF MY VIDEOS IS a hoover with no motor I have now perfected pitty I have not got the funding to sell this hoover I would make millions A HOOVER THAT HAS NO MOTOR OR IT CAN BE USED AS A LEAF BLOWER...... LOOK OUT MR DYSON TECH MOVES ON</p>
I'm quite confused. In your video it says 20pf or 40pf trimmer cap, but in your written instructions 8t says 15pf or 40pf trimmer cap. Please kindly explain.. :)
<p>it doesn't matter that much as long as its in 20% ime and have been a television engineer if all the parts were 20% either way it would not matter</p>
<p>40pf for sure</p>
<p>I know it's a silly question and I think I already know the answer but still, please tell me. Does change in Inductance of a coil affect its range? If so, how are both related?</p>
I'm facing the problem while transmission . The signal is jumping eventually
<p>Works fine but I got 1 Problem: The Microphone is really silent...i got to turn my mobile on full volume to get decent volume in the radio...is there a way to amplify the mic more?</p>
<p>how if i use the value trimmer capacitor 120pF..can or not?</p>
<p>Hi, i tried to make it with exact component but still not getting any output. Any help?</p>
<p>can i operate it at 5 volts? I want to revise it design and make it run with USB power.</p>
<p>If you remove the resistors in the correct places and place a wire there instead, you might be able to run it on a lower voltage.</p>
<p>where does the middle pin of the capacitor go?</p>
I think that it should go in the transistor<br>
I am not able to get 4pf ceramic capacitor. Can i replace it with any other component?
<p>I was just wondering how would you increase the range of this?</p>
<p>its probably the antenna. if you want a very long range but in one direction make a yagi. if you want just more better range in all directions (not as good for range as a yagi but better then a piece of wire) make a dipole. you could also make a rf amp but the battery life would suffer and it would be bigger (also you would need to modify the PCB design)</p>
<p>This transmitter is literally impossible to tune without a non-conductive screwdriver. It really should be a part of the list of required tools!</p>
hello friend i have a confusion in assembling the 3.5mm audio jack in place of mic can u please explain or send a pic to me

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Bio: Hi I'm Angelo! I am a 18 y/o college sophomore taking my majors in BS-ECE at the DLSU. I use my course as ... More »
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