DIY Bluetooth Speaker!

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After weeks of waiting, the parts I needed for a homemade Bluetooth speaker arrived. Pictured above are the PAM8403 amplifier board, Bluetooth module (USB powered with a 3.5mm audio jack), and a couple of 3-watt speakers. The power supply is a 5V 2A power supply I had laying around. All of the project materials amounts to roughly $13.

I got the inspiration from a couple of my favorite YouTubers — GreatScott and David Watts. They had much more polished finished products with a good quality speaker and cool enclosure… I had neither of those.

The project itself was simple enough: Break open the Bluetooth module, apply power to it, and then take the audio signals to the amplifier which would drive the speakers.

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Here’s the Bluetooth module cracked open. My original intention was to remove the audio jack and USB plug to end up with a flat board, but the desoldering did not go well as I didn’t have any solder wick. After some failed tries with my desoldering pump, I ended up cutting off the edge of the board with the USB plug, and giving up on removing the audio jack. There were two copper pads near the USB plug that were labelled Vcc and Ground so I used them to apply power instead of bothering the with the pads of the USB plug.

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Wiring it together did not go as simple as I thought it would either. I tried connecting wires directly from the pins of the audio jack to the amplifier board, but it didn’t work. The audio jack was still working with headphones, and the speakers worked faintly when connected directly to the audio jack. (The speakers arrived a bit banged up so I was worried they may have been broken.)

After some time troubleshooting, I ended up replacing the PAM amplifier board (I bought a few, exactly for situations like this) and spliced the included 3.5mm audio jack cable and used that to connect to the amplifier board. I was so happy to hear the power-on tone that the Bluetooth module makes!

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After some playing around with it, I realized that there was only static coming out of one of the speakers so I chopped that one off. I’m not a audiophile by any means so I’m easily impressed… I was pleasantly surprised in the audio quality from these cheap speakers. Even with just one speaker, it can get pretty loud without sounding bad.

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Time to put everything into an enclosure! This was my first time using foam board. If I didn’t use foam board, I’d still be using cardboard. Now that I’ve given it a chance, I can definitely see foam board being my go-to material for this sort of thing. My cuts are a little rough but I learned later on that using a new blade and/or cutting at an angle will give you cleaner cuts.

I used some needles to keep the foam board in place while I used hot glue everywhere.

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Once I was finished putting it together, I printed out a simple nameplate for the speaker.

The Bluetooth module board has a blue LED that blinks rapidly when it isn’t connected, and once every 3 seconds when it is. Honestly, it wasn’t intentional, but my design with raised bottom, which was intentional, worked in the LED’s favor as it gives it a neat glow underneath the speaker. The nameplate originally had a note about how the rapid blinking meant it wasn’t connected, but my printer wasn’t having it…

So that’s it! It only took me half the day from start to finish and I am satisfied with the final product. I hope you’ll take this post as inspiration to whip up your own Bluetooth speaker!

Thanks for reading!

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Clock Project Journal Entry #2: Get on with it

In the first journal entry for my clock project, I introduced the purpose and general idea of the project. It’s simple, but it’s been dragging on for weeks. The schematics and PCB designs have been tweaked many times since the first draft. I’ve been hesitant to call them complete because of my unfamiliarity with the DS3231 real-time clock, and because it’s my first time making my own component parts in Eagle. After some focused work today, I’ve sent the boards off to be made.

There are a couple of aesthetic aspects to these PCBs that are new for me: Larger size and different color. Both the control board and display board are larger than the 5x5cm (or less) size that I was always aiming for before. The larger boards give me a lot more room to play with when I’m routing the connections. It also lets me breathe a little easier knowing that the text sizes should be large enough to read… I’ve have cases where I made text too small just because I didn’t have space for anything larger. The boards will have black soldermask because I think it will make the LEDs stand out more and will hide the control board a little better. I’ve always gone with blue before.

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As I mentioned earlier, this will be my first PCB with custom made parts designed in Eagle. The two parts that I made were for the power switch and the DS3231SN IC. The power switch is a tiny slide switch that I ordered a bunch of a while back. They’ve always been hard to use because of their somewhat odd form factor. The pins are tiny, it has two thick outer support pins, and has a 2mm pitch so it isn’t breadboard-able. I ordered digital calipers just to measure the switch’s pin thickness. Hopefully I got it right. If it turns out to be fine, I’ll probably make another PCB order for some breakouts for these switches.

The DS3231SN’s datasheet links to another document for its land pattern, which shows the spacing and sizes of the pads. The land pattern is clear so I’m confident that I made the part right in Eagle. Time will tell!
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Since Eagle limits board sizes and the price for anything larger than 10x10cm would probably be too expensive anyway, I could only fit two digits on a board for the clock’s display. Each segment is made up of two parallel branches with a resistor and two LEDs in series. The resistor I plan to use are 1K 0805 surface-mount resistors. I tested them out in this configuration on a breadboard, thanks to my own 0805 breakouts. I chose the relatively high value of 1K because the brightness seemed to be just right, although it could still feel too bright when the entire display is put together. Time will tell on that as well.

I’m still trying to decide how I will put the two panels together. I want to have the colon in the middle of them, whether it’s made of LEDs or not doesn’t matter to me. I also don’t have much of a plan for an AM/PM indicator so the project may start off as a 24-hour formatted clock and be changed to a 12-hour clock in the future.

As you can tell, I’m still trying to get things sorted out even after the project milestone of getting the boards made being surpassed. I ordered the components for this project a couple of weeks ago from China so I hope they arrive soon. There are also a few components I’ll purchase locally when the other things start to come in.

Thanks for reading!