How to Work an FM Transmitter for a Car

Updated March 23, 2017

FM radio transmitters broadcast the audio from an iPod or other portable media player to the radio in your car stereo. These devices are low-power, so their broadcast signals are designed to only reach your own radio, without disturbing the radios of other nearby cars. FM radio transmitters work best when they are tuned to a radio frequency which is not used in your area.

Connect your portable media player to the FM transmitter. Some transmitters work through the headphone jack on the player, while others connect through other ports, such as the iPod proprietary connector.

Select a radio frequency for your FM transmitter. This is usually done with a button or dial on the transmitter. Typically, an LCD display will show you the frequency you have chosen. Use a frequency which is not shared with a radio station in your area.

Tune your car radio to the same frequency as the transmitter. You should be able to hear the media player’s audio through the car speakers. If you hear excessive static, try adjusting the position of the transmitter.

Adjust the transmitter’s frequency as necessary when you drive. Many trips will take you into the range of other radio stations, which may interfere with your transmitter. If you hear two audio signals on your radio, change the frequency until you find another one that is not being used.


Adjust the settings on your transmitter and radio only when you are not driving. It is dangerous to be distracted by these devices when the car is in motion.

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About the Author

Ellis Davidson has been a self-employed Internet and technology consultant, entrepreneur and author since 1993. He has written a book about self-employment for recent college graduates and is a regular contributor to "Macworld" and the TidBITS technology newsletter. He is completing a book on self-employment options during a recession. Davidson holds a Bachelor of Arts in American civilization from the University of Pennsylvania.