Introduction: USB Powered Speaker



My laptop's speaker isn't loud and I have hard time listening to it when there's noise. Alternatively i have a speaker that runs on battery, whose battery drains fast. so i built this speaker which is powered by USB .

Step 1: Circuit and Components Required

The components required for this project are :
  • LM386 IC
  • 8 pin IC base
  • Type A USB Connector
  • 3.5mm Audio Cable
  • 8 Ohm Speaker
  • Two 220uf Capacitors
  • 10K Pot
  • 10 Ohm Resistor
  • soldering iron, solder
  • hot glue (optional)

Step 2: Wiring in USB Cable

Cut the USB cable from any old USB device which is broken or not used. You will see four wires inside the cable when you strip it. The color of four wires are usually blue, white, red and black. The blue and white wires are data wires and are not of interest in this project. The red wire is the positive voltage that comes from the USB port which is +5 V and the the black wire is the ground.

  • Red wire +5 Volts
  • Black wire Ground

Step 3: Wiring in Audio Connector (3.5 Mm Audio Jack)

I've stripped cable of an old headphone. As you can see there are 4 wires. blue colored wire has right audio signal and the green colored one has the left side audio signal, the two copper colored ones are the ground wires.
The wires coloring may be different in different cables, to make sure of the coloring use the continuity test in multimeter.
connect the green and blue wires together and the ground wires together as we are not building a stereo speaker here.
  • The green and blue wires together form the audio input
  • The copper wires are connected to ground

Step 4: Connecting the Components

Connect the components on the general purpose PCB according to the circuit diagram. the 10 K pot will be used to control and vary the volume of the speaker.

Step 5: Casing for the Speaker

I used the food container for the casing. cut out the bottom of the food container in the shape of circle with a diameter less than that of the 8 ohm speaker.

Step 6: Fitting the Components Inside the Casing

make holes for the pot which will be used as a volume control and the USB and audio cables. Use hot glue to stick them in position and close the container.

Step 7: Finishing

Add a knob for the potentiometer, and any other modifications to make the speaker look good.