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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

<p>If your transmitter does not work - and you verified that all connections are OK - then it may be that the oscillator does not oscillate (I've found it the hard way). Desolder your antenna and try again at close distance. I've used the (advised elsewhere) quarter-wave flexible wire antenna and my oscillator worked only at super high frequencies. At lower ones it was damped down - see attached images.</p>
Can copper 22 # gauge wire be used instead?
I want to know insteaded of 100nf and 10nf capacitor we can use 100uf and 10uf capacitor and how to calculate frequency in therotical
<p>any body tell me </p><p>how can i set the frequency on our fm radio</p>
<p>set your fm radio to the lowest band... try 88.9</p>
<p>Is there a reason your questions get posted so many times ?</p>
<p>can i use smartphone's radio to read frequency from fm transmitter.</p>
<p>yes I tried it.</p>
<p>Hi I made your instructable... I used a mono socket for my microphone. I'm planing to use it as a wireless mic. I also replaced the 4 pf with 5 pf because it's unavailable and used 22 swg 9 turns instead what you did in your instructable. Nice work ;)</p><p>...Anyway how can I improved the signal without touching the microphone? The reception improves clearly when I curl the wire of the microphone with my hand. </p>
<p>I couldn't buy trimmer capacitors because I couldn't find in store(here is only one store where you can buy Electronic components)and I have other trimmer capacitors with different capacity and will this work if I will use it?</p>
<p>any body tell me </p><p>how can i set the frequency on our fm radio</p>
<p>go through the video first <br>at the last you can see that he(the tech guy) adjusts the screw on the top to get get the desired frequency<br>first you need to set the frequency through you wanna hear in the receiver<br>then adjust the screw until you can hear clearly<br></p><p>let me know if it works </p>
<p>any body tell me </p><p>how can i set the frequency on our fm radio</p>
<p>any body tell me </p><p>how can i set the frequency on our fm radio</p>
<p>any body tell me </p><p>how can i set the frequency on our fm radio</p>
<p>but not work</p>
<p>but not work</p>
<p>Hi, so I made this on a breadboard and it works. My radio can pick up my voice (and a lot of noise). <br><br>But the main problem I'm not sure how to solve is that I have to be talking directly into the tiny electret microphone in order for it to work. <br>Even if I'm 2 inch away, it won't work.<br><br>How do I solve this problem? <br><br>Is this a problem because I am using a breadboard? I don't think that would affect how sensitive it is to my voice? But I expect that it contributes to the background noise.</p>
<p>wow.. trying to build it in breadboard.. but cant find the output frequency.. can u tell about your inductor.. what wire and how many turns.. if you can reply with your circuit image it will be so helpful for me.. Thank You .. </p>
<p>same problem here</p><p>it is not working</p><p>7 turns of copper wire for inductor</p>
<p>same problem here</p><p>it is not working</p><p>7 turns of copper wire for inductor</p>
<p>same problem here</p><p>it is not working</p><p>7 turns of copper wire for inductor</p>
<p>same problem here</p><p>it is not working</p><p>7 turns of copper wire for inductor</p>
<p>do you maybe have a schismatic of how you did it on breadboard. mine does not seem to work </p>
<p>My transmitter is broadcasting on 17 MHz range i think its the inductor, could i just buy a .1 uH inductor component instead of making a coil?</p>
<p>i do it but not working in any way</p><p>can you help me</p>
<p>my project dose not working any way</p><p>please any body help me as soon as posible</p>
<p>Hello,</p><p>Could I use a 2n2222 instead of the 2N3904?</p><p>Thanks</p>
<p>can you please attach corel draw x4 cdr file of pcb layout</p><p>please reply as soon as possible .</p>
<p>Hey everyone</p><p>I'd love to rebuild this project , but I did not find the right parts. Would it be possible that someone publish a link collection.</p>
Thanks for this nice posting.
pcb layout size in printer machine plz
<p>dimention of pcb </p>
<p>aprox 350 x 150 mm</p>
<p>Hi. Thanks for this instructable, I haven't tried this for a long time! Though it seems like I have some problem with the soldering, I need to review it ;)</p>
Thanks dude. Works great.
Pcb layout size of print what?
Sorry, I'm not sure what your question is exactly.
<p>is it possible to connect a LASER as the input to the transmitter and then decode the signal at the receiver so as to make a wireless counter?</p>
<p>I made it and it works. But when the voice is loud signal is losing and starts to buzzing. When i whisper to the mic i can hear my voice from radio clearly. Every quiet sounds become louder even tick tocks of wall clock.</p>
<p>Can you maybe show the other side. my arrangement is the same, but i don't get a transmission.</p><p>Thanks</p>

About This Instructable

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Bio: Hi I'm Angelo! I am a 17 y/o Physics Major at the DLSU and I use my course as an inspiration for making ... More »
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