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Thread: trying to mod this fm transmitter board

  1. #1

    Default trying to mod this fm transmitter board

    hi,
    well i was looking online and found that with the belkin tunecast 2 you can mod it to extend the range http://www.sonic.net/~n7moe/BelkinMod.htm . i went to amazon and bought a similar generic brand one and cant understand the circuitry in it at all. i took some pictures of it and hopefully someone can assist me in how to go about extending the range or if this item was a complete waste of money. thank you


  2. #2
    Moderator TLHarrell's Avatar
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    Default Re: trying to mod this fm transmitter board

    The squiggly thing on the corner is an antenna. You might be able to extend it. You might not. Changing the size of an antenna can change the frequency it receives, not just it's gain. I'd try attaching a jumper with an alligator clip to the antenna and trying it out before doing anything more permanent.

    These are extremely low power transmitters, designed for very short line of sight applications. While you can expect better reception within a vehicle, which is what they are designed for, you're certainly not going to get it to go much beyond that by doing a passive mod. You really would need some sort of FM repeater. And then you'd be falling under different FCC rules.
    I have a hammer! I can put things together! I can knock things apart! I can alter my environment at will and make an incredible din all the while! -Calvin

  3. #3

    Default Re: trying to mod this fm transmitter board

    What I ended up doing was rigged up a power source and took a small piece of wire and touched it to various parts and found that connecting it to l1 gave the best reception. One thing I noticed before and after is that I need to touch either the audio jack or the end of the write I soldered on for it to transmit better.I'm not sure if this is a grounding issue or if its something else and how I would go about fixing this problem

  4. #4
    Moderator TLHarrell's Avatar
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    Default Re: trying to mod this fm transmitter board

    Probably would get a better result on a forum for electronics and/or RF design. You are using your body as part of the antenna. Good thing it's low power stuff you're playing with.
    I have a hammer! I can put things together! I can knock things apart! I can alter my environment at will and make an incredible din all the while! -Calvin

  5. #5
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    Default Re: trying to mod this fm transmitter board

    yup. what you're dealing with is 1/4 wavelengths and some serious electronic black magic. i agree with harrel, you'd get much better advice from an rf forum.

  6. #6

    Default Re: trying to mod this fm transmitter board

    Ok thanks I will move it over there. Doing this project because the guy next to me at work told me he would drown out my ipod with his radio so I'm blocking his radio. Looks like my next project will be a tunable phono oscillator because he also will play am stations

  7. #7
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    Default Re: trying to mod this fm transmitter board

    i think it would be cool to see what progress you make though. don't think we're trying to chase you away.

  8. #8
    Undead Pirate d_stilgar's Avatar
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    Default Re: trying to mod this fm transmitter board

    I would look for a few things on the board for starters. Mind you, I'm no expert in electronics, and most my circuit bending skill comes from fiddling with things until they do what I want.

    The modification of the transmitter to be more powerful will almost certainly break some laws, so make sure that your final signal doesn't broadcast all over the neighborhood or else you might get some men in suits looking for you.

    I would start by looking for resisters, potentiometers, or voltage regulators. If there are potentiometers, then get out a little screw and turn them one way or the other. You might be changing the frequency at which you transmit, which is nice for finding an empty channel to broadcast on, or you might just let more power through to broadcast at a longer distance.

    Same goes for resistors. Try replacing them with smaller ones or even adding a potentiometer of your own so you can mess with it and see what that does.

    Finally, voltage regulators. If you can find them, these are the most likely culprit for regulating the power of the broadcast signal.

    Also, it sounds like your problem might be fixed in a much simpler way, like by using something like this: http://www.afrotechmods.com/cheap/jammer/jammer.htm

  9. #9

    Default Re: trying to mod this fm transmitter board

    I know you guys weren't trying to ” chase me away” you were just directing me to better because you didn't know the answer as well. At tops I would be transmitting 15 ft so I don't think I would be seeing any men in suits and it would be for ten minute bursts at a time

  10. #10
    Undead Pirate d_stilgar's Avatar
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    Default Re: trying to mod this fm transmitter board

    Just make sure all you do is 15ft. You may just want to get this other guy at 15ft, but may inadvertently get people blocks away as well.

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