I’ve wanted a Bluetooth speaker when working in the yard or around the house. There are a lot of options to purchase one, JBL makes a great item, but it’s too much money for what I need. Since bluetooth/amp boards are cheap, and the speakers required are small, the project should be inexpensive to put together. The first step was to spec out the hardware needed, and then to create a drawing to work from. The drawing is available as a downloadable PDF.
Most of the supplies were on hand (buttons, laptop power supply), but there were three things that needed to be purchased:
One of the nice things about this PCB is the range of operating voltages, initially it will be used with a laptop power supply, but it will also run off the solar/battery setup that will be installed in the shed this spring.
To begin, all the speaker cabinet pieces were cut according to plan, holes drilled and dry fit together. With everything fitting together correctly, it was glued and clamped. Because it is MDF, it will absorb a lot of glue, so be generous during assembly.
After the glue dried, the speakers were installed and circuit board installed. Also, holes were drilled for the buttons, where were counter sunk using two different sized forstner bits, I did not use a backer-board so there was some tear out. Repaired using 5 minute epoxy. After that was completed, all the surfaces were lightly sanded and edges rounded over.
Initially the grill was going to be this metal screen that was purchased at Menards.. so it was cut to use using tin-snips. Later, that idea was abandoned in favor of computer fan guards. The screen was then removed, a little more sanding then a few coats of black paint using a roller for a smooth finish.
Fortunately the switches that were in the parts pile can be illuminated with a LED. So, five while LEDs had their leads cut down to size and inserted into the switch. The wiring will accomplished with ribbon cable, it’s thin and very flexible. To utilize the switches and the chassis mount power jack the existing surface mount components had to be first removed from the PCB. Because the wires were surface soldered to the pads, and not via through holes, hot glue was used as a strain relief so the pads would not lift off.
The LED is wired to turn on when the button is pressed, and get’s it’s power from the laptop power adapter (16VDC) through a 1k 5w resistor. The buttons and power are wired up, so the buttons could be mounted and speakers wired. The power jack is attached to a fender washer that is counter-sunk and epoxied on the back panel. Some fiberglass insulation was stuffed in each speaker enclosure to eliminate the echo sound.
And that completes the project. The sound quality is OK, there is some noise that can be heard at low volumes, this seems to be an issue with this board, as I have read other comments from other people with the same problem. If the volume is up, it’s not so noticeable. Since there is not a heatsink on the amp, it’s unknown how well this will hold up at volume for an extended period of time… More to follow.
Here’s a brief video showing the unboxing of the amplifier board, and a sound test of this cabinet.