Instructables

Boosting Fm transmitter range

I bought a FM transmitter for an ipod. I would like to boost the range of the device. (I know it is illegal but would like to get more range than 2 feet.) I think I need to build an external antenna but need to know where to hook it up to the thing. The transmitter I have is a ge FM transmitter for ipod.If anyone has done anything like this or have any useful links it would be great. I don't know anything about circuit making so help would be great on that as well.


double_g1 year ago
I found this: http://www.youtube.com/watch?v=FY3s8OpFbEI

Basically the method seems to be to eliminate power limiting devices for the antenna on your board and then replace the antenna with a better one. There are also power amplifiers (not used in the youtube link) which actually amplify signals. I doubt the FCC will come knocking on your door if you boost the range a bit, but if your neighbors down the street start complaining about interference you might have a problem :D.
rbucher2 years ago
Couldn't you just hook up an external antenna and raise that to the top of your roof and broadcast as far as you need it....i found this one Click Here which they say broadcasts 150 feet?
With my little fm transmitter I got from walmart in the automotive section for 12$, I had a range of like 5 feet for clear signal then it diminished from there. Really decent for it's purposes. Ran on 2 AAA.

then, in the last week ive been getting into trying to boost it's signal and google told me that if I attach a ~69mm wire onto one of the terminals where the battery touches, it should boost the signal. I obeyed the almighty google and boom. A huge increase in range. Went from about the 5 feet or so to a distance longer than my house (that's as far as I tested it, it's freezing where I live, don't judge).

Getting greedy, tonight I attempted to bump the power supply, said bollocks to increments and threw on a 12 volt drill battery. BAD IDEA. I know that now. But I'm gonna get a new one, except they no longer carry the EXACT same model.. Although, they carry an updated one (I assume it's updated) so I'll get it and mess around with it then post results!
tycoonist4 years ago
I saw a link below about FCC compliance.

I did a little research for a project im doing and the FCC non-licenced, "low power" transmitter range is 200 meters, or roughly 210 yards by my crude math.

In layman's terms: you can broadcast any fm signal in a less than 200 meter range that doesn't interfere with you local radio stations.

Here is a good transmitter worth looking at for a first radio project.
http://www.cie-wc.edu/fmtransmitter.asp
Bloody eYe4 years ago
::: pls I'm newbie ... leave the antenna i have the circuit of lpfm and NachoMahma says (Even the best antenna isn't going to give you much range with a low-power transmitter) my self-made lpfm range is 25metres, how can i upgrade my lpfm to a high-power transmitter? any1 lead me to a link or some information, i'll be thankful,! :-{)
myacirkhan4 years ago
Hi buddies me too require this,,, but i want to boost the range about 5~10 Kilometers at least ..even transmitter require more power
lemonie5 years ago
here, check this out, this guy seems to have the right idea. he even mentions boosting the power with a AAA battery. i haven't tried it yet, but the diagrams make it look pretty fool proof, even if you don't have the same transmitter he has (i don't).

hope this helps, good luck! I plan on modifying mine tonight. just follow the link below.

http://greensboring.com/viewtopic.php?f=23&t=6351

take luck,
nick
It's possible to increase the range somewhat by changing the antenna. Google it - there are guides out there on how to do it.
thejrb (author)  Weissensteinburg6 years ago
Thanks I found a couple links that will work. Maybe I'll do an 'ible on it. Can you help me find the antenna on the original one? I'm not sure if I know what to look for.
On some iTrips, you have to remove a sticker to get the antenna out.
Kiteman6 years ago
Here's a quick thought - if you're trying for range in just one direction, get hold of an old satellite dish. Put your transmitter in place of the old receiver (in the focal point of the parabolic dish), and see what happens.
thejrb (author) 6 years ago
Maybe just 30ish feet. Just so it can go through my house and to stop some loud stereos. I'm not talking miles here lol.
. I seriously doubt that even a perfect antenna would boost your range very much. Even if you triple the range, that's just six feet. Those gizmos just don't have much power.
yeah. however, adding an rf amplifier or 100 watt linear amplifier would help you a lot.
guyfrom7up6 years ago
I'm pretty sure you can't increase the range, there isn't really an antenna (I think), it's just an inductor, which if you change would break the transmitter.
NachoMahma6 years ago
. What kind of range are you looking for? Even the best antenna isn't going to give you much range with a low-power transmitter. . I couldn't find any technical details on the device.