Do you have a spare speaker lying around, or even better: a speaker box? Make it into a blue tooth device.

All you need is a wall adapter to power a blue tooth receiver and a simple audio amplifier, see images. More information on these parts on the next page. You may choose using similar parts with more suitable connectors so less clipping of cables is needed. These were the least expensive parts I could find.

What you need to do:

1. clip the small connector from a USB cable and connect the ground and 5V wires to the corresponding pins of the amplifier.

2. Use two wires to connect speaker output pins of the amplifier to your speaker (box).

3. clip one jack from the audio cable and connect ground and L+R channel wires to the input of the amplifier

4. insert the USB cable and the blue tooth receiver into the 5V wall adapter and you are set!

5. connect your phone to the receiver using blue tooth and stream your music.

Step 1: Parts

I bought the following three parts from eBay for US$ 4.00

TDA2030A Audio Amplifier Module Power Amplifier Board AMP 6~12V 1*18W (US$ 1)

1 .Onboard TDA2030A audio power amplifier chip
2. Single channel 18W power amplifier circuit design.
3. Onboard the loudspeaker wiring seat.
4 .Onboard 10K adjustable resistor, can adjust the enlarged volume.
5 .Onboard power indicator.
6. Chip main has drawn, you can directly enter the audio signal.
7. Working voltage: 6 ~ 12V. (will operate from 5V)
8. Board size: 31.6 (mm) x23.2 (mm).

Bluetooth 2.0 USB Audio Stereo Music 3.5mm Receiver for Car AUX Speaker Phone (US$ 2)

Easy To Operate:Simply connect your speaker with our device,immediately transform your speakers into a fashionable wireless bluetooth speaker. Wireless Play:Removing troubles of wired connection,through the wireless connection and transmission,the user can enjoy a high fidelity music at any place indoor by wireless control Perfectly Compatible:Our products can be compatible with most of mobile phone or computer on the market.Support iPhone,iPad,iTouch and all kinds of smart phones. Portable Design:With mini size,the feature of portable can let you carry them to anywhere you want.

3 USB Ports EU/US Plug 3.1A Universal Wall Charging Adapter For iPhone & Tablet (US$ 1)

Plug type: EU Plug/US Plug
Output: 5V 3.1A(For USB x 3)
Size: 6.8x 5x 2.8cm Output power: 15.5W
Input: 100V-240V AC 50/60Hz

Step 2: Options

If you are not be happy with clipping and soldering cable wires another amplifier may be your choice:

DC12-19V/AC 12-15V Assembled TDA2030A 18W Class AB Mono Audio Amplifier Board

This model also accepts AC voltage up to 15V and it has an audio jack input as well as an easier volume control.

Instead of a second power supply, the 5V from the wall adapter could also be increased using a DC-DC converter, as shown in the second image. This will increase the power output of the audio amplifier. The specifications of the DC-DC step up voltage module are as follows:

MT3608 Step Up Power Apply Booster Module DC-DC 2V-24V 2A