If you've got a car stereo that doesn't have the facilities to dock with portables, USB flash drives or flash cards, then a great way to listen to your digital music is by using an FM transmitter. You can hook up MP3 players / PMPs, CD players, and other devices that have a standard headphone jack. FM transmitters are usually powered by your car's cigarette lighter adapter and work by converting your portable's audio output to an FM radio signal -- this can then be picked up by your car's radio. In fact, any device that can output audio via a headphone jack can normally be used -- cell phones, tape players, etc.
As well as being an FM transmitter for your iPod or iPhone (check compatibility), the Griffin iTrip Auto also comes with a built-in charger that plugs into your car's 12V accessory socket. To start listening to your digital music, you have to select a clear radio frequency to use. The Griffin iTrip Auto has a SmartScan button that automatically selects an optimum frequency to use -- you can also manually choose one if you prefer. The iTrip Auto also has a programmable presets feature that you can use to save the best FM frequencies to use. If you've got an iPod Touch or iPhone, then you can also download a free app from the iTunes Store via the Griffin Tech website; this then enables you to control the FM transmitter using your Multi-Touch display screen.
If you're looking for a budget FM transmitter, then you will be hard pushed to find a better solution for your money than the Coby CA-745 FM transmitter. The unit uses your car's DC cigarette lighter adapter, negating the need for batteries. This power adapter also has a handy pass-through so you can use additional devices that use your car's 12V power outlet. The Coby CA-745 has a bright LCD back-lit display which shows you the frequency that it is broadcasting on. It can utilize the full range of the FM radio band, therefore giving you plenty of scope in areas where there are many radio stations. Overall, the Coby CA-745 is a cheap and cheerful FM transmitter that does a stellar job.
The Griffin iTrip Auto Universal FM transmitter can connect any audio device to your car stereo that has a standard 1/8" (3.5 mm) headphone jack -- this includes: CD players, MP3 players, PMP's, iPod's, etc. This FM transmitter is powered from your 12V power outlet and also comes with a USB port. This great feature enables you to charge your portable device via its USB cable too. Pressing the SmartScan button automatically finds the optimum radio frequency to tune your car stereo into -- manual buttons are also available if you prefer.