Custom Car Bluetooth Receiver

Currently my phone is simply connected to my radio’s AUX input with a cable, and if I want to change songs I must do so from the phone. Modern raidos have integrated Bluetooth capabilities, allowing you to pair your radio to your phone wirelessly. In some cases, pausing and skipping tracks can be done directly from the radio’s buttons – safer than waking up and unlocking your phone to change songs within the music player app.

jvcradio

I could have purchased such a radio, but I already had a perfectly fine JVC unit I installed not even two years ago. It has two AUX inputs, the one in the front I’ve been using, and a special Bluetooth AUX input in the rear. Although designed for use with a JVC accessory, I decided to build my own Bluetooth receiver for my car.

The Hardware

If you’ve already seen my custom Bluetooth headphones, then you’ll recognize the base hardware I used for this project. I am again using the Nexxtech Soaring Bluetooth Headphones. I love these, because they often go on sale for $20 (sometimes less!), the battery life is excellent, they include all the controls you would actively use, and the sound quality is on par with headphones up into the $50 range. They also have a microphone, allowing hands-free calling.

I had a hard time deciding how flexible I wanted this project to be. On one hand, I could integrate it very nicely with my car, and mount it flush with the void underneath my radio. The wiring would all be contained inside my dash, so I could wire the receiver directly to my radio. However, I would not be able to use it for anything other than my car.

In the end, I decided I would create a flexible device, and opted to install a headphone jack, so that I could connect it to anything (car radio, headphones, speakers). This means I can make any set of speakers wireless!

Headphone Jack

The headphone jack was salvaged from the motherboard of an old, failed computer.

The Assembly

Much of this process is the same as the last time around. I disassembled the headphones down to the guts of each side, one containing the battery and USB connector, the other containing the circuit board.

Halves

At this point, I found the perfect place for the headphone jack:

Jack Fit

I decided I would sandwich the two halves together, such that they would form a case. This would make it a standalone device.

Test Fit

Test Fit 2

I cut lengths of thin wire, sized to allow me to easily open the package in the future. I soldered them to their respective locations, (+5V, battery +, ground).

Wires Run

Solder Closeup

Finally, using hot glue, I secured the headphone jack in place, and soldered the Left, Right, and Ground audio connections. I used a multimeter to determine which pins were for which channel on the headphone jack.

Jack Solder

It is definitely a good idea to test it now with a pair of headphones to make sure sound is coming out, before glueing everything together.

In traditional rapid-prototyping fashion, I forgot to take pictures of the actual sandwiching step, but suffice it to say that a bit of common sense, and hot glue, will yield you a result similar to this:

Charging

Sealed Jack

Charging still works, sound comes out, the buttons are functional – all I need to do is install it in my car!

The Installation

Being the 21st of December, the first day of winter, it was proper dark and cold outside at 5PM when I installed the receiver in my car. Despite this, it was actually much easier to do than I feared.

Car Test

I have an aftermarket radio installation kit, replacing the factory tape deck that came with the car. It more or less just snaps in and sits in place, so I didn’t need to remove any trim or dash pieces to pull out the radio.

To test, I simply connected the Bluetooth receiver to the rear Bluetooth AUX input using an audio cable, and switched the input source to BT Audio. Success! All works as planned.

Tucked Away

Tucking the AUX cable behind the ashtray, and inside the dash, makes the installation look much cleaner. I just left enough wire to reach the receiver, which I plan* to mount using Velcro.

Final Location

*I say plan because, as mentioned above, it is winter, and the adhesive could not stick to the surface in such cold.

Remarks

When I turn on the receiver, as long as Bluetooth is enabled on my phone, it automatically pairs within about 5 seconds. All I need to do is hit play on the receiver to begin music playback.

I tested the hands-free calling aspect (at a standstill) and was understood fairly well, and could understand the person on the line fine. Road noise and engine noise might make it impossible to be heard; further trials will need to be conducted.

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Friday, December 21st, 2012 car, electronics, projects


2 Comments to Custom Car Bluetooth Receiver

  • MrBreadWater says:

    I am not doing this project, but fixing some old bluetooth headphones. Any idea what b+ and b- is?

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