Introduction: Bamboo Bluetooth Speaker From Old Cutting Board
There was a time when wired, non-Bluetooth portable speakers were popular. They were cheap, ran for hours on a handful of AAA batteries, and could be easily hooked up to any phone or MP3 player with a headphone jack. Today these are practically obsolete, which means that used units in good condition can be bought for next to nothing.
In this instructable, I'll show you how I added Bluetooth and a rechargeable battery to an old, wired portable speaker. I also put it in a new enclosure that gives it a fresh look. The enclosure is made of bamboo plywood scrapped from an old cutting board – the kind you'd use in the kitchen.
A list of electronic components and tools used for this project:
- One Bluetooth receiver module - this module connects to a device like a cell phone over Bluetooth. It converts the incoming Bluetooth signal into analog audio. The audio is sent to the amplifier.
- One 18650 Li-Ion battery - these are common rechargeable batteries that you should be able to find at your local electronics store. I strongly recommend using brand-name batteries.
- One 18650 battery holder - soldering wires directly to the terminals of the battery is a big no-no. I recommend using a simple battery holder instead.
- One voltage booster module - A Li-Ion battery's voltage isn't constant. It starts at 4.2 volts when the battery is full and drops all the way down to 3.0 volts (or below) at which point the battery is considered empty. Since the amplifier requires about 4.5 volts to work, we need a voltage booster.
- One Li-Ion battery charging and protection module - This module charges the battery cell safely from a USB port (5 volts). It also disconnects the battery from the circuit when it is empty, thus protecting it from overdischarge.
- A simple switch
Tools and extra materials:
- Soldering equipment
- Mini table saw
- Dremel tool
- Flush cutters
- Speaker grill cloth
- Wood screws
- Wood glue, CA glue, 2-component adhesive, hot glue
Note: the links above are affiliate links, meaning I might get a small commission when you use them. The price you pay doesn't change. All links point to stores I've shopped from myself. All the stuff can also be found on Amazon or eBay.
Step 1: Overview of the Board, the Speaker, and the Electronics
As I said in the intro, the enclosure of my speaker is made of bamboo plywood that I salvaged from an old cutting board. This board wasn't of good quality, as its price of $3 would suggest. It developed those dark stains on one of its ends after just a few months of use so I definitely didn't want it in my kitchen anymore.
The good thing was that the board was still flat and had no cracks. All it needed was some good sanding. Its size was about 21 by 29 centimeters and had a thickness of 8 millimeters.
About the speaker, an Altec Lansing Orbit im227, here's why it was an ideal candidate for this project.
- First of all, It was super cheap. I paid something like $5 for it.
- Second, It is a simple device which means that it's easy to hack. There are no playback buttons or connectors to bypass or sophisticated amplifiers to reverse engineer.
- Thirdly, it still sounds pretty good for its size even though it was made in 2008.
- It runs on 3 AAA batteries or 4.5 volts. This means that it can run on the same voltage rail as a Bluetooth receiver. Such receivers usually require between 3.3 and 5 volts.
- And lastly, it uses a standard headphone connector so it's easy to hook up to a Bluetooth receiver.
Of course, if you choose to replicate this project, you don't have to use this exact speaker. However, a speaker with similar characteristics should be easier to repurpose.
Step 2: Taking the Speaker Apart
I started by taking the speaker apart to see what components I could salvage. It was held together by 8 screws, four at the top and four at the bottom. When taking apart a gadget, keep in mind that screws may be inside the battery compartment. They can also be hidden under labels or feet.
Fortunately, there was very little glue to deal with. Some newer or cheaper speakers are glued shut which makes them much harder to open. There was only one blob of hot glue-like substance holding a circuit board in place. A bit of wiggling was enough to loosen it up. Some glues can be scraped off or loosened with hot air.
A few minutes later I had all the parts laid out on the table: two printed circuit boards, one speaker driver, and a bunch of plastics. Do not throw away the plastics! These will later make it easier to cut the new opening for the speaker.
Step 3: Analyzing the Circuitry
The board with the audio amplifier had the speaker soldered directly onto it (pictures 1 and 2). There was no need to take them apart at this time.
A second printed circuit board (picture 3) was originally connected to the amp board with three wires. I desoldered it as I was taking the speaker apart. That secondary board contained the power on/off switch, as well as an LED that turned green when the power was on or red when the battery was low.
Using a multimeter, I found out that pressing the power button shorted two of the three wires (picture 4). I guess the third wire was only needed to detect when the battery was low. I decided to replace this second board with a simpler switch since the low-battery detection wasn't going to work once a rechargeable battery was added to the circuit.
Step 4: Testing of the Circuit, Making Sure Everything Works
At this point, I wanted to make sure that everything still worked so I wired up the components temporarily. It looks messy, I know, but it will look much nicer later on.
I soldered the battery holder to the battery charging and protection module. The output of that module I connected to a voltage booster and adjusted it to 4.5 volts. The output of the voltage booster is connected to both the amplifier board and to a Bluetooth receiver board. Finally, I placed a charged 18650 battery into the battery holder. The blue LED on the Bluetooth receiver lit up, which was a good sign.
Next, I paired my phone to the Bluetooth receiver and started a music player app. With a song running, I shorted the two points to which the switch from the second board was connected. Music started playing.
Step 5: Wiring Diagram
This is what the wiring looks like. Notice that the power on/off switch is placed in a way that allows the battery to be recharged regardless of whether the speaker is powered on.
The voltage booster module is set to an output of 4.5V.
Some may notice that the wiring of the Bluetooth receiver and audio amp creates a ground loop. In my case, this didn't cause any humming or noise. However, if you do have noise in your circuit, consider adding a 0505 isolating transformer between the voltage booster module and the Bluetooth receiver.
Step 6: Sanding the Board
It was time to leave the electronics aside and start chopping that board. But first, I gave it a nice sanding to remove all the black, mouldy parts and all the cuts and nicks from its surface.
Sanding is a straightforward task: you get your sanding block and start sanding. For best results, sand along the grain of the wood; follow the direction of the fibers on its surface.
I started with some rough, 80-grit sandpaper to remove bigger imperfections. Once those were gone, I moved on to 120- and then finally 240-grit for a smooth finish. In the end, the board looked better than new! In pictures 2 and 3 you can see what the board looked like before and after sanding.
Step 7: Cutting the Board
For this step, I brought out my mini table saw. If you don't have a table saw, I suppose you can cut the board into pieces using a circular saw, a band saw, a router or even a manual hand saw. In any case, please use common sense. Be careful and watch your fingers.
My goal at this point was to end up with four pieces of the same dimensions. The board wasn't big enough to provide all six sides of my speakers.
I wasn't aiming for any dimensions in particular. I just trimmed the board and tried to get four identical pieces as large as possible. The pieces I ended up with were 8.6 by 11 centimeters in size.
Step 8: Cutting Dados and Rabbets
At this point, I had a clearer idea of what the speaker was going to look like. The four bamboo pieces were going to be the sides of the speaker, while two additional plywood pieces were going to be its front and back.
But before I cut the front and the back pieces, I made dados and rabbets in the bamboo pieces. If you're not familiar with woodworking terminology, there are basically slots in which wood pieces fit. This creates a stronger joint between pieces.
I made the rabbets and the dados on the table saw by running the piece over the blade several times. The 3D rendering here, showing two of the four pieces, should give you an idea of where the dados and rabbets were made. Pictures 3 and 4 show the pieces with the dados and rabbets cut in them.
Step 9: Trim Plastic Piece for Speaker
Pictured here is the plastic piece to which the speaker driver was originally attached. You can see on picture #2 how it has a slot shaped and sized specifically for the driver.
I decided to reuse this plastic piece for my project instead of wondering how to attach the driver to the enclosure. The plan was to glue the plastic piece to the front side and then attach the driver from behind. The plastic piece was also going to serve as template for the circular cutout for the speaker.
The plastic piece was too big to fit inside the new enclosure so I trimmed it as much as I could. Then I sanded its backside until it was flat.
Step 10: Glue Plastic Piece and Cut the Hole
Honestly, this step wasn't the smartest, but all was fine in the end.
I glued the plastic piece to a piece of plywood using CA glue. Then I used my router and a flush-trim bit to cut a circle in the plywood exactly as wide as the original speaker cutout. Unfortunately, the CA glue had stuck the plastic piece to the plywood too well, and acetone wasn't able to loosen the glue's grip.
Step 11: Separating the Plastic Piece
At this point, I realized that to retrieve the plastic piece, I had to destroy the plywood it was glued to. That's why I made a backup copy of the circular cutout. I transferred it with my router onto another piece of plywood.
Next, I used my router to remove as much of the wood as I could. Eventually, the plastic piece snapped off with a little force. Some thin plywood fragments were still holding on to it, but a little sanding took care of those.
Step 12: Making a Slot for the Plastic Piece
Using a pencil, I traced the shape of the plastic piece onto the backup piece of plywood. Then I made a slot for the plastic piece into the plywood. It didn't have to be perfect. Having a little wiggle room was fine, as any gaps were later going to be filled by the glue. Picture #4 shows the plastic piece inside the slot.
Step 13: Trimming the Plywood Piece, Adding Rabbets
Using my table saw, I trimmed the plywood piece to size. Picture #1 shows the rear side, to which the plastic piece was to be glued, and picture #2 shows the front. I was feeling fancy, so I added a slight roundover to the opening with the router.
Then I added rabbets to the piece by running it over the table saw. You can see the result in picture #3.
Step 14: Dry Fit
Now was a good time to put all pieces together (no glue) and to make sure that they fit. I had to shave off about a millimeter from the plywood piece to make it fit well, but it was no big deal. Overall, things were going great so far.
Step 15: Gluing the Plastic Piece to the Front Side
Knowing that everything fits together, I could confidently glue the plastic piece to the front side of the speaker. I used 2-component adhesive for the job because it would fill in gaps if there were any.
Step 16: Cutting Back Piece + Second Dry Fit
I used my table saw to cut another piece of plywood for the rear of the speaker. This was NOT going to be the back side. The purpose of this piece is to have something the back side to attach to later. You'll see what I mean in a bit. I made rabbets in that piece as well for a better fit inside the rear dados.
Once the piece was cut, I made a second dry fit. All pieces fit together well enough.
Step 17: Making a Cutout in the Rear Piece
I used my Dremel tool to make this cutout in the rear piece of plywood. The cutout was needed to provide access to the electronics, just in case. Another piece of plywood is going to cover it.
Step 18: Gluing Battery Holder
I decided to glue the battery holder at this point. Otherwise, it would be too hard to glue it inside once all pieces have been glued together. I simply glued a small piece of wood to the inner side of the enclosure and then glued the holder to it with CA glue.
Step 19: Glue It All Together!
The time has come to glue the side pieces, the front side, and the rear piece together. It was a matter of applying regular wood glue to the dados and rabbets and cIamping it all together. I let it all dry overnight.
Step 20: Cutting the Back Side
The back side of my speaker is made of solid wood. It is just big enough to fit while leaving a hair-thin gap between itself and the walls of the speaker. It is going to be screwed in place at a later time, once all the necessary electronics are attached to it.
Step 21: Drilling Holes and Countersinks
I wrapped the piece in a couple of layers of painter's tape to prevent it from moving around. Then I put it in its place and drilled four pilot holes where the screws were later going to go. I used a countersink bit to add countersinks for the screws so that they lay flush with the surface. You can see what the bit looks like in picture 4.
Step 22: Making a Frame for the Grill Cloth
I wanted to add a grill cloth over the speaker driver for protection. To add one, I first made this frame out of four pieces of wood 10mm wide and 3mm thick. I cut lap joints to make them stick well to each other. Notice that the frame is about 1mm shorter on each side. This is to leave room for the cloth to be tucked in as the fabric is quite thick.
Step 23: Gluing the Cloth to the Frame
I cut a piece of fabric with plenty of excess material on all sides. The excess was to be trimmed off once the glue-up was done.
On the front, the cloth and the wood are glued together using 2-component adhesive. I chose this adhesive because it doesn't dry too quickly. I applied a thin layer to the wood surface and then put the frame over the cloth. I also added a small block of wood on top to add a bit of pressure (but not too much!) for better adhesion.
About 30 minutes later, I wrapped the fabric around the sides of the frame and glued it. This time I used CA glue because it dries quickly. I used a block of wood to apply uniform pressure as the cloth was bonding with the wood. Then I trimmed the excess fabric.
The last picture in this step shows you what a sheet of this fabric looks like.
Step 24: Spray Lacquer!
Nothing fancy here. I gave the speaker a few coats of matte spray lacquer to make that bamboo pop. I let it dry overnight. As you can see here, all openings were covered with painter's tape during the spraying process.
Step 25: Preparing the Power Input Port
The battery charging module had a microUSB port on it already, so I decided to mount it directly onto the back piece. To do this, I used a few thin scrap pieces of wood to create a "holder" of sorts. I layered the strips of wood like so and glued them together to form what's shown in picture 2. Then I trimmed it with my Dremel tool like shown in picture 3.
Step 26: Cutting Openings in the Rear Side
For the power input port glued to the wooden holder I cut a wide, thin opening. I started the hole with my Dremel tool and then finished it with a small chisel.
Once that was taken care of, I cut a circular opening for the power switch.
Step 27: Putting It All Together
Finally, I wired up the electronics and closed the enclosure with short screws. The cloth grill is tucked into place and held to the front of the speaker by a dab of hot glue. I used a toothpick to tuck it in place.
Step 28: It's Finished!
At last, this project is complete! I am happy with it overall. The look of the speaker makes it stand out, and the sound is okay for something of this size (and made out of old junk).
I'm not quite happy with the back side of the speaker. I know nobody's going to look at it, but I feel like I could have done a better job.
Anyway, I hope you liked this instructable. If you have any questions or comments, please leave them below.
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