How to make car audio/stereo (mp3/bluetooth/radio) for $10

[audio (mp3, bluetooth, radio) module]
 

In this article I will show you how to connect this mp3 bluetooth audio module to a car.
You can buy this module on ebay or aliexpress It costs about 4$. You can find links below this video on youtube. In my previous video I've already demonstrated a similar device. But this module has a slightly different design. It has a native bluetooth support with an zigzag antenna on a PCB and accepts micro SD card. This module was shipped with an infrared remote control. The device has a linear regulator to provide a regulated 5 Volts output for the digital circuits. So it can work with 12 or 14 Volts which almost any car can provide.


[blaupunkt car stereo]
 

 
In order to install the audio module We should make some preparations.
So I've removed my previous audio system. As you can see It's a Blaupunkt car stereo system. Actually It was sold to me with the car. It can only play CD and radio stations.



[ISO connector]

Let's examine connectors which we have from the previous audio system. So I googled and It turned out these are a standard ISO 10487 connector and a steering wheel control connector and also an antenna connector.

 



First of all. To start the audio module we need to connect it to the power source.
I'm going to use the standard ISO connector. If you look at pinout you can see there are 2 positive power pins. #4 - BAT and #7 - IGN. #4 BAT is always connected to the positive terminal on a car battery. And IGN pin (I believe it means ignition) is connected to the battery only if the car key is inserted into the ignition and rotated to the first notch. Usually the first notch on the ignition is labeled as 'ACC' It stands for 'accessories'. The first position enables usage of the radio and other electrical accessories. I think BAT is not for me because the module would be constantly connected to the battery and therefore It would suck power from the battery. So It could be possible after some time there is not enough juice into the battery to start the car engine.

[ speakers ]


I presume you already have speakers in your car. I have speakers in all of my car's doors.



[ amplifier ]
 
  Next thing. We need an audio amplifier because the audio module output has not enough power to drive the car speakers.

You can harvest an amplifier chip from your old car audio system. For example my previous audio sytem has a pair of TDA7375. If you look at a datasheet for this chip you can find a typical circuit to use it as an stereo system.

Of course you can buy a ready made module for a few dollars. I'm going to use this audio amplifier module. It consists of TDA7297 chip and can provide about 15 Watts for a channel. I have only a 2 channel amplifier but you can use a 4 channel amplifier. Output of the amplifier I will connect to the front door speakers. If we look at pinout they are pins #5 and #6 for the left front door speaker and #3, #4 for the right front door speaker.

[ ground loop isolator]

The next thing we need is a ground loop isolator. Actually It's a pair of audio transformers. I will place it between the audio module and the amplifier. It eliminates all noise caused by ground loops. You may want to watch my other video where I discussed these phenomena in depth. The ground loop isolator costs about 3 dollars. On other hand you can harvest audio transformers from an old modems.

[ devices connection ]

 
OK let's connect all the devices,
In picture you can see a wiring diagram


[fuses]


Do it at your own risk. Keep in mind If you can't avoid short-circuiting the electrical system during the installation then you probably would blow your audio fuses and you would have to replace the broken ones. In my car the audio fuses are located behind the left front door.

[Links]

Youtube: How to make car audio/stereo (mp3/bluetooth/radio) for $10