modifying fm transmitter circuit 3


Posted on Feb 5, 2014

To this small FM transmitter to change the mic for an audio jack so I can plug it into my mp3 player to listen to songs on my car audio. I looked at some of the transmitters on this site, but I think I`m going to go with this one, as I find it simple, and only need like 10 feet range (not even probly. ) rip out the mic, connect the base of the transistor to a capacitor. Now connect the


modifying fm transmitter circuit 3
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other end of the capacitor and the -ve to your MP3 player speaker output. A 0. 22uF coupling capacitor from the MP3 player is fine. You should connect both stereo outputs from the MP3 player each to a 47k series resistor. Connect both 47k resistors to the coupling capacitor and a 0. 1uF capacitor can be used. Connect the grounds of the MP3 player and transmitter together with the shield of audio cable and the audio signal inside it. It is not necessary to connect the MP3 player`s output "backwards". Just connect its output to the coupling capacitor added to the transmitter and connect the grounds together. That FM transmitter is so simple that its radio frequency will change all over the place if you get near it, if the battery voltage changes or if the temperature changes. Since it doesn`t have pre-emphasis (treble boost) like radio stations have and radios have the opposite, reception from it will sound muffled without treble frequencies. :lol: Also, "connect the grounds of the mp3 player and transmitter together with the shield of the audio cable and the audio signal inside it" I`m not sure what your saying there. and what ground from the mp3 player Anyway, I`m really short on cash, and I`m doing this more for the learning experience than actually using it (although I probly will use it. ). Also, I`ve read that you have to use ceramic capacitors for transmitters like this. just checking if thats true. 2) The battery...




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