Add Bluetooth to Your Old Car-Hifi




About: Italian maker, law student, DIY enthusiast. I make lots of projects, I fix lot of stuff and I like to save and reuse materials taken from broken stuff.

Hi everyone!

In this quick ible I'll show you another way to upgrade your old car with just 5$ and less than 30 minutes of work. If you want to check out the last simple upgrade that I made on my car, you have to see my ible "Thermometer - Upgrade Your Old Car".

I'll basically suggest you how to EASILY add the Bluetooth on your old radio (or on a cheap one like mine).

Since I'm an university student I have to study a lot and, specially during the exams period, I have no time to work. But I also hate to ask money to my parents so the only way for me it's to save my money, and to use them wisely.

When I received my 2001 Fiat Panda Young from my brother, I bought this very cheap radio (I think it cost me 25$). It is a quite good radio...I mean I know that it's not the best on the market but for just 25$ it has Aux, USB, SD/MMC card reader, CD reader and various music settings.
Every saturday, when I go out with friends they always want to play their fresh-downloaded songs, so I give them the aux cable to connect their phone to my radio. It's a good solution, but...connect them through the bluetooth wouldn't be a better and a cooler solution?? :P

SO...I simply ordered the cheapest Bluetooth audio receiver on the web, and I tried to obtain the cleanest result possible hiding it in the radio hole. I gave it power connecting it to a 5V portable battery and I also added a ON/OFF button to prevent it from discharging when the bluetooth receiver it's not used.

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Step 1: Materials & Tools


- Bluetooth audio receiver (5$)

- Portable battery

- ON/OFF button

- Heat shrink tubing

- Old usb (male to female) cable


- Soldering iron and solder

- Scissors

- Dremel

- Drill bits of different sizes

- Marking pen

Step 2: Understand the Circuit

Since I bought the Bluetooth receiver with the plastic cover (I didn't buy just the circuit), I could have powered it just plugging it to my radio through its usb end, and through the small aux cable that comes with it, but I wanted to mask and hide it, making the result of this small project as clean and natural as possible.

So I decided to power it through a 5V portable battery (which can be bought easily on the web for few dollars), and to add a button to prevent the useless discharging of it.

P.S. I opted for the second possibility also because, due to the cheap radio itself, when I power the bluetooth audio receiver through the radio, it makes a loud and annoying sound that makes me go crazy!! :O If anyone knows the reason, I would be grateful to understand it.

Step 3: Solder Wires to the Button and Modify the USB Cable

In this step we just have to solder two wires to the button, and to modify the usb cable.

I cut the usb cable into two parts, than I resoldered the negative wires together, and I added two longer wires (blue and blue/white) to the existing positive-red ones. I insulated all with heat shrink tubing, letting the ends of blue blue/white wires uncovered.

(this will be helpful when we will have to connect them to the button, after installing it under the car lighter).

Now you should have something similar to photo#4.

Before going to the next step, I suggest you to check if everything works out as it should.

So I quickly twisted the wires of the button, I plugged the bluetooth audio receiver into the female usb port of the cable, and I plugged the male usb port of the cable into the portable battery.

As you can see in photo#6, pushing the blue button the small blue LED of the receiver lights up properly.

Step 4: Choose the Button's Place

I choose to put the button under the cigarette lighter so, in order to access there easily, I simply removed the radio from its hole.

I started by removing the radio panel, its frame, and then I simply pull out the radio from the hole. There are no screws here, except of those "metal springs" that keep the radio in place (photo#4).

Step 5: Make the Hole and Insert the Button

I quickly marked the place of the hole with a marking pen, and then I used the dremel to make it.

I started with a small drill bit, then I enlarged the hole with a bigger one.

In order to make the hole as neat as possible I tested the dimension of the hole, and then I filed it a little with a round file.

When the hole it's perfect you can insert the cable, and then you can screw from behind the panel his nut.

CAUTION: Make sure to wrap the exposed ends of the wires with a small piece of electrical tape, to avoid possible contacts with the back of the cigarette lighter.

Step 6: Connect and Hide Everything

Now it's time to join the 4 wires of the button, and to insulate them with two pieces of heat shrink tubing.

Than connect the bluetooth audio receiver to the battery through our modified usb cable, and put everything in the radio hole.

I decided to keep the result as clean as possible without making another hole for the mini-aux cable, so I simply plugged in one end of the mini-aux cable to the receiver, letting the other end pass in the gap under the dash panel (photo#5).

Step 7: Finish!! Show Your Upgraded Radio to Your Family and Friends!!

Well done! With just 5$ we have upgraded an old radio.

NO MORE WIRES!! If my friends want to play their songs, I simply ask them to turn on the bluetooth on their phones, and with just a click of the blue button, the magic it's done!! You can control the music in the range of 10 meters from it (also if you stay out of the car).

NOTE: My Bluetooth audio receiver connects automatically with all the phones I tested, but if your phone asks a code, enter 0000! ;)

MIND THE GAP! When your battery will run out you will not have to remove again the radio! You will just have to pull the battery out from the gap, disconnect from the usb cable, and after recharging it, you can put it again under the radio. (photo#2)

Thank you for reading my Instructable. ;)
Feel free to comment and ask if you need to know something!


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    26 Discussions


    4 years ago on Step 2

    Hi, I think it is a ground loop problem. you can try to cut off the ground line of the audio cable, so that groud only comes via USB Bus.

    1 reply

    4 years ago

    Ciao, complimenti per il tuo Instructable! Volevo chiederti, ma l'interruttore da quanti volts è? Va benissimo uno da 12v nonostante la corrente sia a 5v?

    1 reply

    Reply 4 years ago

    ciao francesco! realtà ne avevo uno che mi avanzava da un vecchio progetto ed ho usato quello...

    comunque l'ho comprato su ebay qui


    4 years ago on Introduction

    Why did not you just connect your Bluetooth receiver to car-hifi's power supply? With a little bit of modification you would achieve this


    5 years ago

    The loud buzzing/humming sound you hear is a ground loop. A ground loop isolater will solve the problem.

    2 replies

    I dont think a ground loop is formed, its probaby high frequency transients. Maybe a cap across the two power cables will work. Try 100nF electrolytic.

    El Torro

    5 years ago

    Very nice, but you might consider hacking an old cell phone charger and tying it into the power wires of the cigarette lighter to power the dongle instead of using a battery.

    4 replies
    maniacseEl Torro

    Reply 4 years ago on Introduction

    Another solution is the 5V USB charger (just reduction from cig. lighter to USB female). In my previous car I bought this kind of 12V-5V "reduction", disassemble it, bought short USB male to female cable for panel mount, connected it together and hide everything under panels. You can use it for charging Your devices, and when You need, charge the battery. Or You can make it only for charging battery, and then it can be hidden completly. Or if You use some filters, You can leave battery and use it directly to power up bluetooth modul. I will do some of here mentioned setups in few days from now, I am just waiting for my Bluetooth adapter to arrive. Also, manuelmasc, thanks for sharing, for me mostly this idea - powering with battery/power bank: it is also great, if You do not want to use filters - total simple and brilliant.


    Reply 4 years ago on Introduction

    Thanks very much @maniacse you are very kind. please send some "I MADE IT photos" when you'll finish!

    Even if it works very great and the battery last more than a month (I listen to music every day a couple of hours), I think that in the next future I'll update it adding a voltage regulator. I made this project in this way (just powering the bluetooth receiver through a power bank) because, first of all it was a fast solution, and then because it's much more safe, since I didn't have to work with dangerous high amperage of car circuits!


    Reply 4 years ago on Introduction

    Yep, no problem, I'll post some photos as soon as all material arrive. It will take aprox. two weeks. Cross fingers to everything go great! :)


    5 years ago

    u r car stereo already have usb port than no need for battery just plugged in

    1 reply

    5 years ago on Step 2

    Have you tried it with just the USB and no aux cable plugged in. The radio may be trying to access both signals and it's causing feedback.

    1 reply