Convert MP3 Player FM Transmitters from wireless transmission to wired

Hello

As mentioned above, my question is about how to convert the wireless transmission of the MP3 Player FM Transmitters to wired to car radio, I want to remove the broadcast via fm waves and send sound through wires to the radio using an aux input, knowing that the mp3 Player FM Transmitter does not have an aux output

What is required, then, is the following:

- Add aux output for MP3 Player FM Transmitters

- Disable the device's wireless transmission feature and send data from aux output of the device to the aux input of the radio.

These are the pictures of the device

finally, thank you for your help