Portable Stereo Speaker

Details

The amplifier is based on 2x2 LM380N-8 that gave a pretty sound on the first tests. Stereo circuit is also doing well, look at the scheme attached to see how I built the whole thing.

It needs a 12V voltage supply and give back a 2.5W output power. I linked the amplifier to two Visaton speakers (FRWS 5 SC). I soldered everything on a prototyping plate which makes everything look cleaner. The sound got better too.

I have received the Bluetooth module I order on ebay. After some hesitations about how it's working, I've added it to the circuit and it works! I still got some noises, I'll try to fix it with some capacitors at the input.

Details also available here. The bluetooth module needs a 3 - 5V battery. For the moment, I am only an external battery, I'll have to look for a solution to integrate it in the circuit.

Components

4 × LM386N-8 with IC socket http://www.ti.com/lit/ds/symlink/lm380.pdf

1 × KRC - 86B V4.0 Bluetooth module

2 × speaker 2-5W Visaton FRWS 5 SC

1 × 1000uF electrolytic capacitor

4 × 4.7uF electrolytic capacitor

Project Logs

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Working on the battery
Aymeri • 09/14/2016 at 07:42 • 0 comments

We are looking for a cheap and efficient way to charge the amplifier and the Bluetooth module. We are trying to use a remastered version of the Minty Boost from Adafruit to deliver a 3V-voltage to the Bluetooth module and a 12V-voltage to the amplifier. Not working well though, the current is far too high from what we should observe according to our calculation. The sound from the speakers is very noisy.
Bluetooth module test and power supply
Aymeri • 05/13/2016 at 13:02 • 0 comments

Now that I have received the module, I have added it to the circuit accordingly to the scheme. The LED is blinking when the module is on and stays on when a device is connected.
At first I forgot to solder a simple wire to the "EN" pin (for enabled I presume), it simply did not work... After correction, it worked pretty well! Next steps are to deal with volume pins.
To supply 12V power to the stereo amplifier, we worked on a little device that deliver it with to AA batteries. We are going to write another hackaday project for this one.
Testing stereo and soldering
Aymeri • 04/22/2016 at 14:32 • 0 comments

A few days ago we received the chips we hadn't to start the stereo. So we ran the tests on a breadboard and it worked pretty well! A few noise we reduced using 47pF capacitors at the audio input.
So I updated the scheme and added the second speaker. As we have not receive yet the bluetooth module, we are simply using a jack to test the whole thing. We got a 60mA current for a 12V voltage.
Next steps!
Aymeri • 04/08/2016 at 09:56 • 0 comments

Now waiting for the bluetooth module to arrive! I also need to work on the design of the box to get good results in low frequencies and how to integrate volume control buttons in the box.
I also ordered another audio power amplifier, the LM386, to make other quality tests.