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Long-range Stero FM Transmitter

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birla

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I am trying to make a Long-range Stero FM Transmitter. I'm looking at a minimum of 2km range with stable and clear transmission.
I have been looking for circuits for some time now...but I couldn't find anything which suits my requirements (and availability of parts!).
I'm a noob at electronics so it's been pretty tough...lol

PS: I know such a range is illegal in most countries but here it's not because we come under the category of an *educational institution*
and the college is willing to get a proper license, but not a proper transmitter :(
 
I'm a noob at electronics so it's been pretty tough...lol

...we come under the category of an *educational institution*
and the college is willing to get a proper license, but not a proper transmitter :(

This all screams..."go out and buy a commercial transmitter". You are not going meet the requirements of a "proper license" with a "noob" built transmitter.

Though i do commend you for your effort. :)

Ken
 
As noted, this is not something you want to try and build from scratch. The cheapest way is likely a kit such as this **broken link removed** which outputs 1W of RF power. It probably costs less than if you bought the parts and did it yourself.

It should get you near the range you need with a good antenna mounted on a high location, but if you need more power, you could add a linear RF amp at the output.

EDIT: This antenna **broken link removed** has 3.4dBi of gain so it would be the equivalent of over 2W of output from the above transmitter to a standard dipole.
 
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I am trying to make a Long-range Stero FM Transmitter. I'm looking at a minimum of 2km range with stable and clear transmission.
I have been looking for circuits for some time now...but I couldn't find anything which suits my requirements (and availability of parts!).
I'm a noob at electronics so it's been pretty tough...lol

PS: I know such a range is illegal in most countries but here it's not because we come under the category of an *educational institution*
and the college is willing to get a proper license, but not a proper transmitter :(
Your college appears correct
If an FM Tx is purchased, it may have to be used. then obviously the student community would like to pump in continuous music. at then end of 3 or 4 years, many of them end up mediocre and reduce their chances of getting employed, in the present world of DOG competition.
It is very simple to suggest you one power amplifier block as used by Motorola or Philips and if you adopt it to BH1417F based Micromiteer (Silicon Chip of Australia), your job is done.
BTW, if the institution is not interested, what is the point in spending much on this project from our (students)personal finances as the allocations made available are just sufficient.
 
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The transmission will only last for 5 days as it will be used in
our college fest, so spending $400 + $130 is not that good a deal!
I think that a hand-made transmitter would be a more appropriate
solution for this...! Please let me know what you think.

kchriste : I'll keep that link in mind..thanks!
 
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And one more thing...how do you make a coil? Say if these are the instructions:
L1 - 4 turns of 20 SWG wire close wound over 8mm diameter plastic former.
L2 - 2 turns of 24 SWG wire near top end of L1.
(Note: No core (i.e. air core) is used for the above coils)
L3 - 7 turns of 24 SWG wire close wound with 4mm diameter air core.
L4 - 7 turns of 24 SWG wire-wound on a ferrite bead (as choke)

How do i get the Impedance right?
 
And one more thing...how do you make a coil? Say if these are the instructions:
L1 - 4 turns of 20 SWG wire close wound over 8mm diameter plastic former.
L2 - 2 turns of 24 SWG wire near top end of L1.
(Note: No core (i.e. air core) is used for the above coils)
You simply find an object, such as a pencil, with an 8mm diameter and wind some 20 SWG (18-19 AWG) magnet wire over it in a neat coil. Close wound means that the turns are almost touching but not. When the coil is wound and the leads are formed, you can withdraw the pencil. L2 is also wound on the same pencil next to L1. They should remain in this orientation when mounted on the PCB.
How do i get the Impedance right?
Wind the coils as per the instructions, an it'll be correct. You can spread or pinch the turns of the coil to fine tune the inductance.
A wire gauge chart to help you:
Comparison of Wire Gauges

transistor495 said:
kchriste, you are really a genius. A linear thinker
Thank you! Sometimes the KISS method is the best solution. :)
 
I am trying to make a Long-range Stero FM Transmitter. I'm looking at a minimum of 2km range with stable and clear transmission.
I have been looking for circuits for some time now...but I couldn't find anything which suits my requirements (and availability of parts!).
I'm a noob at electronics so it's been pretty tough...lol

PS: I know such a range is illegal in most countries but here it's not because we come under the category of an *educational institution*
and the college is willing to get a proper license, but not a proper transmitter :(

If you have already made the Transmitter it is fine. In case if you have not then here is the link

ElectronicsInfoline.com | PIC Projects | DIY Projects | Electronics Schematics | Hobby Circuit | EDA Software Tools | Technical Articles

from where you can purchase the transmitter. I do not know whether it works on a normal telescopic antenna or on a yagi antenna (i do not know how to construct a yagi antenna). If you have made the transmitter and that is working fine please mail me personally on ronaldo81@rediffmail.com.

Regards.

PRASAD
 
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