FM transmitter - please point me to the right direction

[eebhoi01]

Hello Everyone,

I will be making a FM transmitter as our project. I know there are lots of FM transmitter on google but i dont know which one is really working and has the greatest accuracy. I wanted my transmitter to be able to transmit within 80Mhz to 110Mhz range.

Anyone who have made some outstanding circuit and is willing to share the schematic and parts list please let me know. Thanks


P.S Dont worry about the implementation of the project, I am willing to work even if the schematic is quite complicated.

 

[tpetar]

Use MAX2606

 

[captainshahid]

it is simple and i have tested it...

 

[captainshahid]

you can change frequency with in the range u want by presetting the variable capacitor

 

[eebhoi01]

Use MAX2606

View attachment 70013View attachment 70014

Thank you sir, by the way what is the Unf in the schematic stands for?

View attachment 70015
it is simple and i have tested it...

Thank you also, I will see if the Chip is not available in our local store I Will go with this schematic thanks anyway ^_^

 

[tpetar]

Thank you sir, by the way what is the Unf in the schematic stands for?

Unf is point for input of signal.

 

[eebhoi01]

Unf is point for input of signal.

Sir, I am planning to make L = 390 for 100-106 MHz. But how can I can further tune the circuit to adjust it from 100 to 106Mhz. Can I use the MAX2606 package that has 6 terminals? Thanks

 

[tpetar]

You can put trimmer smd inductor and fine tune freq. Of course you can use ultra small SOT23-6 package.

**broken link removed**

 

[rahulpsharma]

How far can this signal go?? What are the ways to increase the distance of transmission??

 

[xylon89del]

The distance of signal transmission depends on your operating frequency, environment and transmit power.

In your case, you can increase the transmit power by adding power amplifier before the antenna.

Cheers,
Engineering helps make the world a more convenient place to live in. That's what makes it great!

---------- Post added at 05:19 ---------- Previous post was at 05:00 ----------

You can put trimmer smd inductor and fine tune freq. Of course you can use ultra small SOT23-6 package.

**broken link removed**

tpeter,

you mention about trimmer smd inductor. I tried to search through the internet, but can only find some variable inductors manufactured by China. Is there any more reliable manufacturer you know of?

 

[tony_lth]

Coilcraft has trimmer smd conductor, some are pin package.

 

[thebadtall]

hello, here's a valve 800watt FM Transmitter.
If only you can find the parts , wich I think is too hard to find today.
drive : 6c4 oscillator, 5763 buffer, 6146 driver low voltage
main valves 4x150A. - supplied at 2kV !! (found on ebay $25)
Ive seen this transmitter broadcasting when I was 6-7years old, however, its waves are still travelling to the outer space.
As about range.. I dont remember but it will definately cover you !

 

[E-design]

Page points out common design errors for transmitter circuits.

http://www.talkingelectronics.com/projects/Spy Circuits/SpyCircuits-3.html

 

[E-design]

The electret-mike bias resistor values recommended by the website seem to go against most manufacturer's application notes.
They use very high values (47k-68k) while most application notes recommend values between 2.2k and 10k. Some application notes also warn against using very high resistance values because it will be prone to unwanted noise pickup.