36

Build Bluetooth Speakers

BRIAN PALMER / DIRECTOR, DIGITAL MEDIA SERVICES

Library and Academic Technology at Washington College

Type of Library Best Suited for: Any

Cost Estimate: $114 per participant

Makerspace Necessary? Yes

PROJECT DESCRIPTION

As a society, we’ve generally grown beyond the days of the mid-twentieth-century Heathkit, when the economical solution to owning electronic devices was to build one from a kit. We live in a disposable world, where most people don’t know what’s inside the devices they use, and when those devices stop working, we discard them. This is where makerspaces play a crucial role in educating our youth and adults alike, helping people realize they can make many of the things they want, and even create new tools and toys the world may never have seen before.

The Bluetooth Stereo Speaker project is designed to increase maker confidence, enabling students to create something useful with their hands from components and raw materials, instead of buying a sealed product with no understanding of what makes it tick. During the build sessions explained here, instructors can draw parallels to related real-world component-based systems, like electric vehicles and personal computers, thereby helping students to become active participants in solving problems as makers.

FIGURE 36.1

Bluetooth Speaker build components

OVERVIEW

Building Bluetooth Speakers introduces makers to a number of different technical, design, and fabrication concepts. This project was designed as the final project in our “Cultivating a Maker Mindset” first-year research and writing class at Washington College, but it also encourages students to be makers outside the classroom and as part of our Makers Union student club. At the college level, we encourage students to make the project their own. This optional customization starts as individual consultations with any students who express a desire to customize their speakers. Instructors then steer them to be prepared to make those customizations, whether it means adding or changing electronics or considering different materials and methods of construction.

The Bluetooth Speakers can be as unique and interesting as the students who build them, and can be as much an expressive extension of themselves in visual appearance as the choice of music they play. The speakers also serve as a fantastic advertisement for the library or makerspace, sparking conversations about their origins.

Although a kit can be purchased online, like those from Kitables (https://​goo.gl/​zCkPmM), we decided to design our own kits for our students, allowing us to choose specific components for what we feel is a much better finished product. This also allows us to take into account the customization interests of each student. In addition to the instruction in this project, we encourage you to reference the “Additional Online Resources” collection of files we’ve curated just for this book (https://​goo.gl/​KVN65W). This includes the Illustrator designs we created for our laser cutter, our wiring diagrams, and updates to specific hardware and components we found useful.

MATERIALS LIST

Required parts for building each kit

Quantity Price Each Item

1

$24.99

Rockler—DIY speaker kit, 5-inch woofer

https://​goo.gl/​x5Qfxt

1

$39.90

Wondom AA-AC11162 Bluetooth amplifier

https://​goo.gl/​y9486w

1

$7.99

Wondom AA-JA11113 battery board

https://​goo.gl/​Mvhqhh

1

$4.99

Wondom AA-JA11112 interface board

https://​goo.gl/​u10SKO

1

$1.31

5.5 mm x 2.5 mm DC power jack

https://​goo.gl/​3r015e

1

$7.90

15-volt AC to DC power supply

https://​goo.gl/​qXeszG

1

$9.00

½ pack of 6 EBL 18650 lithium batteries

https://​goo.gl/​pjf7g5

1

$0.35

1/20th pack of power switches

https://​goo.gl/​ZJnfhG

1

$1.78

1/5th pack of M3 nylon standoffs

https://​goo.gl/​t7Tew1

1

$7.50

¼-inch thick 5 x 5-foot Baltic birch plywood, from local supplier

1

8

$0.08

#4 x ¾-inch pan head screws (buy a box of 100 for discount)

8

1

$4.00–$8.00

Finish of your choice (we used clear and black spray paint)

1

NECESSARY EQUIPMENT

STEP-BY-STEP INSTRUCTIONS

1.5–2 Months before Build Day 1

Buy all the necessary components well in advance. It’s best to purchase an extra set for the instructor to use while demonstrating the assembly and one or more extra sets of parts in case someone breaks something. In a pinch, the instructor can give up his parts as well in order to keep a student’s project moving forward. Note: We chose these stereo components for their great quality and price value, but at that time their manufacturers were often short of stock. Order these well in advance. Use the “Additional Online Resources” link for recommended substitutions if necessary.

1 Month before Build Day 1–Optional

Meet with the students who will build these speakers and give them an overview of what the project will entail. This is a good chance to explain where they may be able to customize and alter the plans, which will be greatly enabled/limited by your makerspace’s equipment and support. If there are additional supplies the students will need, order them now. We had students customize parts such as the type of wood used, decorative laser etching, and even the integration of electronics for sound-reactive LED lighting. You can see examples of some of the students’ creations in the “Additional Online Resources” link.

Make sure it is clear to the students that they will need to put in additional time outside of the scheduled build sessions if they wish to customize their speakers. As the instructor, be sure you can support and steer what they are asking to try if they are new to these technologies.

1 Month before Build Day 1

We wanted to tackle the soldering for the DC power jack and the power switch in advance of the build days in order to simplify the project. We did the soldering for them and supplied the finished DC jack cable and DC power button cable as part of their kits to prevent a project build bottleneck.

Now is a good time to laser cut the plywood enclosure pieces. Each speaker has six flat sides, four thin internal brackets, and three small pieces for a volume knob. Since there are two enclosures per kit you are building, this totals 23 pieces per student. This cutting will take time! On our laser it took about 25 minutes of cutting time per kit with ¼-inch Baltic birch.

In the “Additional Online Resources” link, you will find an Adobe Illustrator file that has the design layout for a set of speakers to be cut from ¼-inch Baltic birch. We used the free www.makercase.com utility to create a finger-jointed box with the interior dimensions of 9¾ × 5¾ × 7 inches, then modified it as needed in Illustrator to fit all the components. You can use our designs as is, but you may find that a little more preparation work will save you materials and time in creating multiple kits. Considering the bed size of the laser cutter in your makerspace (or in your local makerspace if you don’t have a laser in your library), create an Illustrator document the maximum size the laser can use. Copy the pieces from our design and lay out the parts in order to best fit them and to minimize wasted material and unnecessary pre-cutting of the plywood into laser cutter-friendly sized sections from the 5 × 5-foot original sheets. Once you have a game plan for your cutting, purchase the appropriate number of 5 × 5-foot sheets of Baltic birch. Often you can have the lumber yard make the major dividing cuts, which will make the wood easier to transport with a typical car and save you some cutting time later.

After laser cutting all the wood pieces, organize the wood, various electronic components, and speakers into individual kits for the students. We used recycled cardboard boxes for each student.

FIGURE 36.2

Cutting the wood pieces

Build Day 1: Overview of Components and Enclosure Assembly

  1. 1. Start with an overview of the project and the components used. Explain what each component does. Have students open their kits and follow along with their own parts in hand for a closer examination. You can tailor this discussion’s depth to the ability level of the group.
  2. 2. Next, take the wood pieces for one enclosure and lay out the front piece face down on a worktable. Align the top, bottom, and sides all facing down so the finger joints mesh up like a big plus symbol. Apply glue to the finger joints and assemble the pieces into a rectangular box, leaving off the back panel for now. Use clamps or blue tape to hold them together while they dry. Glue the four thin internal support brackets around the inside perimeter of the rear opening, leaving enough depth for the rear panel to sit flush when it is screwed on later.
  3. 3. Important: Use a damp paper towel to clean off glue squeeze-out now while it’s easy to remove. Repeat the glue-up assembly process for the second speaker enclosure and set them both aside to dry.

Build Day 2: Finish the Enclosures and Build Speaker-Wiring Harnesses

  1. 1. Begin the second day by removing the clamps or blue tape from the enclosures. Each student should use a sander or hand sand the wood enclosures to prepare the surface for paint or clear polyurethane. Before painting, clean off the sanding dust. We used an air compressor to blow the dust off the pieces. Don’t forget to prepare the rear panel as well!
  2. 2. Take the enclosures and rear panels to a location where you can spray or brush on your paint or clear polyurethane. If you don’t have a good location due to fumes and overspray, consider using a low-odor water-based wipe-on polyurethane or water-based paint and brushes. Give the enclosures a light first finish coat and leave them to dry.
  3. 3. Returning to the worktables, lead the students through the diagram for building the two wiring harnesses for the speakers within each case (provided in the “Additional Online Resources”). There are differences between the harnesses in the powered and the passive speakers, so be sure the students follow the wiring diagram carefully. It is likely some students will poorly crimp some wires, which will easily pull apart. Have them test their crimps by gently pulling at the connections. Have a pack of similarly sized crimp-on connectors ready to allow them a second try at crimping any bad connections.
  4. 4. To finish up the day, return to the enclosures and give a second light coat of spray-on finish. It should be dry enough for a second coat if they didn’t apply the first coat too heavily. Tell them the first coat is not fully dried yet, so they should be careful not to handle the speakers between coats or they may get fingerprints in the finish. Leave the speakers to dry until the next build day.

FIGURE 36.3

Wiring the speakers

Build Day 3: Installing the Components and First Test of the Speakers

  1. 1. Begin by reviewing the electronic components with the students, and walk them through connecting the main Bluetooth amp with the interface board and the 18650 battery board with the supplied ribbon cables. Be sure to point out that the cables only fit properly in one direction (make reference to one side of the connector having ridges or however you best identify the cables in your kit if they happen to look slightly different).
  2. 2. Continue by following the wiring diagram we supply in the “Additional Online Resources” link. It outlines the connections between the components, as well as the LEDs, volume knob, DC power jack, speakers, and other parts that are mounted on the front and rear panels of the powered speaker. Stack the 18650 battery board on top of the Bluetooth amp using 3-mm standoffs, which also provide legs to support the stack in the bottom of the powered speaker. A generous blob of hot glue will secure these feet to the bottom inside of the powered speaker. As shown in the wiring diagram, the passive speaker is much simpler, getting its audio feed out of the terminal cup on the powered speaker and into the terminal cup on the passive speaker.
  3. 3. Before you close up the two speakers, each with four #4 ¾-inch screws, loosely stuff half the acoustic insulation from the speaker kit into each of the speakers, which will improve the low-frequency performance of the speakers. Finally, you can connect the speakers with the remaining foot of speaker wire, or use other speaker wire you provide to separate the speakers further on a desk or across a bookshelf or room. With the speaker’s power on, you’ll notice your Bluetooth-connected phone can control the volume, as can the wired volume knob on the face of the powered speaker. It is great fun to see the students’ faces light up as they reach the moment when they can play music from their own phones on their speakers.

LEARNING OUTCOMES

As a result of this project, students will:

RECOMMENDED NEXT PROJECTS

There are several projects that can stem from what was learned in the Bluetooth Speaker build project. Here are a few suggestions using some of the same tools and types of components: