DIY Mobile Boom Box

Updated: Nov 17, 2018




Hello everyone ! In this tutorial I'm going to show you, how I built this Mobile Boombox.For simplifying the built process I have prepared the stencils for it.Everything in this project can be built by using common hand tools. So anyone who have some basic cutting tools, can build it during the week end. You can gift this Boombox to your beloved during the Christmas.

Wish you " Merry Christmas "


Specifications :

- Dual 5W (4ohms) 40mm Drivers

- Sensitivity: 80 dB

- Frequency O/P : 140 Hz

- 3400mAh Rechargeable Li-ion Battery

- 2 x 5W Bluetooth Amplifier

- Mini USB Charge Plug

- Battery Protection

The project was inspired by Barry_L's Instructable : Simple 10w Bluetooth Portable Speaker. I would like to give special thanks to Barry L,he helped me a lot during the building process.

Full Project is also available on Instructables

Step 1: Materials and Tools Required:

Materials / Parts :

1. Bluetooth Amplifier Module ( eBay )

2. Speaker Driver 2 x 5W ( Banggood )

3. Passive Radiator ( eBay )

4. 18650 Li Ion Battery ( GearBest )

5. Li Ion Charging Board ( eBay )

6.Boost Converter ( Amazon )

7. 4mm MDF sheet

8. 20mm Plywood

9. Self-adhesive Rubber feet ( Amazon )

10. Sliding Switch ( Amazon )

11. 22 AWG Wires ( Amazon )

12. Wood Glue ( Amazon )

13. Super Glue ( Amazon )

14. Masking Tape ( Amazon )


Tools:

1. Jigsaw ( Amazon )

2. Drill ( Amazon )

3. Oribtal Sander ( Amazon )

4. Soldering Iron ( Amazon )

5. Hot Glue Gun ( Amazon )

Step 2: Design and Planning


First I planned the speaker and then designed it on Autodesk fusion 360.The dimensions of all the components are measured by a vernier caliper then the same were considered during the design.

The complete enclosure have 4 parts :

1. Front Panel ( 4mm MDF )

2. Back panel ( 4mm MDF )

3. 2 x Middle Panels ( 20mm thick plywood )

For front and back panel you can use Baltic birch plywood for better look.

Step 3: Making the Stencils


After finalising the design, I made the 2D drawings for all the panels.

The stencils are printed on a A4 size paper.Then cut it out with some margin by using a hobby knife or scissors.

The stencil files can be Downloaded from Instructable step-3

Step 4: Glue the Stencils


Glue the stencils on the mdf / plywood.I used glue stick to stick the stencils.

You can also use spray glue to stick the stencils.

Step 5: Cutting the Panels



The most tricky part is cutting the front panel.First cut the two circle by using a 35 mm spade drill bit or a hole saw. To cut the slots for passive radiator, make a hole at the interior of the drawn area,then use a jigsaw or scrolling saw to cut the desired shape.After cutting there may be chance that the edge are not smooth. In that case just use a sand paper to make it perfect.

Step 6: Peel Off the Stencils

Wet the stencils by using a damped cloth, then leave it for few minutes.Peel off the papers.

Place the panels for few hours on the sun light for drying.

Step 7: Mounting the Drivers and Passive Radiator


The speakerdrivers have inbuilt screw holes for mounting.But as the MDF panel thickness is only 4mm, so I prefer to glue it instead of screwing.Use super glue to mount the drivers.I preferred Gorilla Super glue gel, as it takes some time to dry out. So that you can align the driver along with the slots.

After mounting the drivers,seal it by using the hot glue.

Repeat the same process for mounting the Passive radiator.

Step 8: Join the Plywood Panels


Apply Wood glue on the plywood panels, then spread it around the surface.

Place the second plywood panel on it, then clamp them together.Leave it over night for proper bonding.

Similarly glue the front MDF panel .

Step 9: Make the Circuit


Before starting the soldering, see the schematic diagram first.The connections are pretty straight forward.Just follow the instruction given below.


Battery Connection :

The difficult part is soldering wires to the 18650 li ion battery.First clean the terminal surface, apply flux on it.then solder a red wire to the positive terminal and black wire to the negative terminal. Solder the wires as quick as possible because excess heat from the soldering iron tip may damage the battery.

I used a TP4056 li ion battery charging module to charge the battery.There are two different type module available in the market. One is Without battery protection chip and another With protection chip.I will highly recommend to use the module which have protection chip and micro USB port.


TP 4056 Connection :

The TP4056 module have 4 output terminals

B+ : connect to battery positive terminal ( red wire )

B- : Connect to battery negative terminal ( black wire )

Out+ : Connect to boost converter IN+ through the sliding switch

Out - : Connect to boost converter IN -


Boost Converter Connection :

Out + : Connect to Vcc of the Bluetooth amplifier module

Out - : Connect to GND of the Bluetooth amplifier module

Finally adjust the Boost converter trim pot to get 6.5V at the output.


Bluetooth Amplifier Module Connection:

LP - Connect to left side speaker + terminal

LN - Connect to left side speaker - terminal

RP - Connect to right side speaker + terminal

RN - Connect to right side speaker - terminal

Step 10: Mount the Electronics Components


Align the micro USB port of TP 4056 module and the sliding switch along with their slots in the back panel.Then apply sufficient hot glue around it.Similarly glue the Boost Converter and Bluetooth Amplifier module.

Mount the battery on the middle plywood panel.

Note: To view the Bluetooth module LED outside, later I drill a small hole ( 2mm ) on the back panel. So during mounting the amplifier module, align the LED with the drilled hole.

Step 11: Make the Enclosure Airtight


To make the speaker air tight, spread the wood glue all around by a paint brush or with your finger.

Step 12: Close the Back Cover


After drying the glue, close the back panel by using 4 half inch screw.

The joint between the back panel and the plywood panel have still small gaps.Fill them by applying wood glue.

Step 13: Sanding and Painting


The joint portion between the panels are not smooth.Sand it with a fine sand paper.If you have a orbital sander, then it will be faster. After sanding with fine sand paper,the surface will become very smooth. Now you can paint the surface by using poly urathene or similar paint. It is clear in colour and gives a nice glossy shiny look.

Step 14: Mount the Rubber Feet


At last you have to make the stand for the Boombox.Mark 4 position symmetrically, on the bottom surface.

Stick the self adhesive rubber fit at the marked position.

Step 15: Pairing and Testing


After building the project, I will recommend to charge the battery with a USB charger.During the charging the the status LED glows red and when it becomes blue indicates that fully charged.Turn on the power switch, the red led on the Bluetooth Amplifier module will starts to blink.Turn on Bluetooth on your smartphone and search for the nearby Bluetooth devices.The name of this device is " CSR8645".Then pair it and play your favourite song.

Enjoy !!!

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