Thread: Need help wiring FM transmitter

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I finally got around to cracking open this guy:


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I am planning on adding an antenna wire to this like in this tutorial:
http://www.christmasdisplays.net/pro...ransmitter.php

I want to use a wallwart for this. I know I need 12v and amps should not matter cause it will use what it needs. What's the best way to wire it up using the fuse?

Also, I see where the antenna wire is soldered to the circuit boards. Should I solder my extended wire directly to the board or snip the original antenna wire and solder to that?

I believe the fuse goes internal to the unit so you should be protected. If you want to add an external fuse you can just put an inline fuse holder in the positive wire going to the unit. Make sure though that you use the same exact fuse. That style of fuse comes in a fast blow (AGC) fuse and a slow blow (MD something) and they are not interchangeable even though they share the same current rating. As for the antenna, I would personally solder directly to the board. Hope this helps.

Is there a 4 post crystal on there? If so there should be a a notch on one side then you want to solder a wire to the post on that side.

So just to be sure, I don't need to use the fuse that was in the plug originally?

Originally Posted by billman

I don't need to use the fuse that was in the plug originally?

Nah I think it would be fine without it.

Well, It 1/2 way worked...I added a female socket for the 12v power of the MP3 player. Now a wallwart or a cigarette lighter will work. However, the range is still the same about a couple of feet.

Sucks, cause I have a huge antenna on top of my house connected by cat5. I was hoping to at least get a mile like in the tutorial. ( sad face )...

I would seem to think that you might need to boost the signal some how.

@Billman

I can't speak for that particular unit, but most portable mp3 transmitters have the antenna built into the 3.5 audio jack. If the audio in jack was hard-wired to the unit then all you need to do is get a audio jack extender and plug the female end into the 3.5 audio jack. This will increase the signal strenth and range.

If the 3.5 jack isn't hardwired then the antenna is inside the unit. Just soldier a stereo wire to the pre-existing wire or to the board's ANT circuit.

Most of these units draw power from either a car or mp3 player battery, so you might want to just go ahead and convert it for wallwart. You can always up the volts a little to give it more power. It should improve signal strength.

You'd better watch out, ... "The FCC won't let me be, or let me be me ..."

You got a licence for that-thar transmitter, son? Not something you want to hear on the BIG NIGHT.