DIY Portable Bluetooth Speaker With Powerbank.

Compact yet powerful single channel speaker with 3W output and built in power bank. Bluetooth Speaker build from Scratch!!

Specifications & Features:

• Bluetooth 4.0.
• 3W Full-Range Speaker.
• 18650 single battery 2600mah.
• Micro USB Charging.
• USB out for charging with constant 1A.

• Bluetooth Module
• 2" 3watt 4 ohmSpeaker Driver Unit
• PAM8403 Class D Audio Amplifier
• 18650 Battery (2600mAh)
• 5V 1A Power Bank Charger Board Charging Circuit Board Power Supply Step Up Boost Module For 18650 Battery DIY
• On/Off Slide Switch
• 1K Resistor X 2
• 2 leds
• Cables
• Heat shrink tubes
• A Desired box

For the Power Bank Charger Board Charging Circuit Board I have recycled an old power bank.

Battery is also recycled from old laptop battery pack.

Here I've used a hard cardboard cylindrical box.

Dimension of the box:

• Diameter: 7.4mm
• Height: 6.5mm

Here I have used 2" driver so using a compass I have made 2" marking on the top side by a marker.

After marking, cut the hole using cutting tools and sand the edges to finish.

Now on the bottom side of the box, mark the position of the USB port, micro USB port, charging LEDs and sliding switch using marker, cut and drill them out.

Make a hole using 3mm drill bit at the front side of the box for the status led.

As I said I have recycled this circuit from an old power bank.

This circuit automatically ONs when detects any load on the output. And automatically OFFs when the load is removed within 10 seconds.

The marked (B+) and (B-) are the points where the battery connects.

(Out+) and (Out-) are the output +5v and GND which are also directly connected to the USB pin onboard.

I had scraped the bluetooth module from an old bluetooth headset.

For power it requires +5v supply. It has 2 channel output which I have made a mono channel using a mono audio filter.

The mono audio filter uses two 1k ohm resistor, as show in the schematic diagram. All grounds are common.

Alternate bluetooth module.

Bluetooth Stereo Audio Receiver Dongle it an good and cheap alternate bluetooth for this project.

PAM8403 class D audio amplifier .

Features
Dual channel stereo output 3 w + 3 w power.

Works with 2.5V-5v power supply.

High amplification efficiency 85%.

can directly drive 4 Ω/8 Ω small speakers.

Good sound quality & noise suppression Unique without LC filter class D digital power board.

Can use computer USB power supply directly.

Here I have used only one channel of the amplifier board.

Connect the the +5v point of the amplifier to the output +5v of the charging circuit and RIN point to the mono audio output of the bluetooth module.

Mount the Speaker driver using hot glue on its place.

I have mount the charging circuit, sliding switch and leds using lots of hot glue.

here the red led is low battery indicator and the green one if for charing status.

Also I have marked the labels using marker pen.

I have made the status led as flush as possible for a cleaner look.Using the given Schematic Diagram solder all the things together. Use isolation on battery terminals.

Using Hot Glue stick the Battery, Bluetooth Module and Amplifier Board on the inner walls of the box.

This project can be further customizable, using vinyl wrap or paints.

To me the original vivid and tangy color of the box looks cool. So I have kept this original.

Audio Quality

The Audio quality is good and very loud though. Nice vocals and crisp sound. Bass is not the punchy, because the box has low volume and not having a harder shell.

The Box is made up of hard cardboard, so it vibrates a little bit when played on full volume.

Battery Backup

Here I've used an 18650 battery with capacity of 2600 mAh. To be honest there was no more room inside the box so i was forced to use a single cell. 2 to 3 cells should be great for this project. This single cell can roughly charge full battery of a cell phone.

Playback Time is around up to 9 hours.