Most audio systems in vehicles today have Bluetooth connectivity. The technology lets you connect your mobile phone to the car’s speaker system to take hands-free phone calls and stream your favorite music or podcasts.
But that hasn’t always been the case. Bluetooth in a car only started becoming a mainstream addition around 2010 — and even then, only about 40% of vehicles had it.
So what do you do if your car doesn’t have such a connection? Well, that's where the Bluetooth transmitter comes in.
While they come in different styles and functionalities, all Bluetooth transmitters work on the same principle. Generally, the transmitter draws power from the car through the cigarette lighter socket or USB port.
Once powered up, it's a two-step process to get it working. The most important thing to remember is that the transmitter uses FM signals, just like a radio station. So first, scroll through the range of FM frequencies on your car’s radio. You are not looking for a specific station but rather an open frequency, like just static noise. So your chances are better of finding some unused airwaves at the beginning and the end of the frequency range.
When finding some airwave real estate, note the exact frequency. Then, back to the Bluetooth transmitter. Tune it to that frequency. Once locked in, pair your mobile device with the transmitter through Bluetooth, and you should hear your music through your car’s stereo.
Without getting too technical, the Bluetooth transmitter acts as a very short-range radio station. It takes the Bluetooth audio from your mobile phone and broadcasts it for your car’s stereo to pick up. If someone else happens to be on the exact frequency and within range, they would be able to hear the music, too.
This transmitter has a 1.4-inch LCD display, making setting it up and changing the frequencies easy. It can also show you track and volume information, who’s calling and the car’s battery voltage. In addition, the flexible gooseneck lets you position it in the best spot, which is important when you want to make hands-free calls. The transmitter is compatible with Android and Apple devices. Sold by Amazon
In addition to the Bluetooth streaming functions, this transmitter has two USB ports on the top so you can charge your mobile devices while driving. It has a simple indicator for the frequency and buttons to control the track selection and answer hands-free calls. Sold by Amazon
This transmitter uses anti-static technology to boost the signal to the car’s stereo for clearer audio quality. In addition to Bluetooth, you can also use the USB slot to stream music or plug in a microSD card. The two USB ports can also charge your mobile devices and is compatible with Android and iOS phones. Sold by Amazon
Working slightly differently than others, this transmitter still connects to your mobile phone, but through a 3.5-millimeter jack. It has a USB port for charging, and the simple display lets you change the frequency with two buttons. Since it doesn’t have built-in Bluetooth technology, it is compatible with most older mobile phones that don’t have it either. Sold by Amazon
A great aspect of this transmitter is not only that it lets your stream your music, but it is a wireless car charger and cradle, too. You simply put your mobile device inside like any other phone holder with a suction cup, and it will automatically charge your device while streaming your audio. The transmitter's frequency and buttons are behind the phone when cradled, so you won’t accidentally press any buttons. Sold by Amazon
This transmitter has two USB ports, but one of them is a USB-C with a 20-watt output for fast charging. For connecting your mobile device, it uses the latest Bluetooth 5.1 technology that provides better sound quality and a stable connection. There is a button on the side to answer phone calls, and the surrounding blue LED backlight pulses with the rhythm of the music. Sold by Amazon
If you are looking for a smaller device than bulky transmitters, this is an excellent choice. It doesn’t work through the cigarette lighter socket for power but uses a built-in battery that can last for up to seven hours. That means you can place it wherever you want to in your car and still use Bluetooth technology and FM transmission signals. However, if you connect it to a USB port in your car, it will automatically switch on and off with your car. It has a large LED display that is easy to navigate and make adjustments. Sold by Amazon
Other than the expected FM transmission capabilities, this has one regular USB port for charging devices and a USB-C port with fast charging for phones that support it. The transmitter has a one-button bass booster, a button to answer hands-free calls and a small display to see the frequency. And it supports the virtual assistants from Apple, Google and Samsung, which lets you ask for directions, get notifications or send text messages without taking your eyes off the road. Sold by Amazon
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Charlie Fripp writes for BestReviews. BestReviews has helped millions of consumers simplify their purchasing decisions, saving them time and money.