2024 Business Card Challenge: CardTunes Bluetooth Speaker

July 20, 2024 by Donald Papp 8 Comments

A business card form factor can be quite limiting, but that didn’t stop [Schwimmflugel] from creating CardTunes, an ESP32-based Bluetooth audio speaker that tried something innovative to deliver the output.

What’s very interesting about this design is the speaker itself. [Schwimmflugel] aimed to create a speaker out of two coils made from flexible circuit board material, driving them with opposite polarities to create a thin speaker without the need for a permanent magnet.

The concept is sound, but in practice, performance was poor. One could identify the song being played, but only if holding the speaker up to one’s ear. The output was improved considerably with the addition of a small permanent magnet behind the card, but of course this compromised the original vision.

Even though the concept of making a speaker from two flexible PCB panel coils had only mixed success, we love seeing this kind of effort and there’s a lot to learn from the results. Not to mention that it’s frankly fantastic to even have a Bluetooth speaker on a business card in the first place.

The 2024 Business Card Challenge is over, but judging by all the incredible entries we received, we’re thinking it probably won’t be too long before we come up with another sized-constrained challenge.

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The Best-Sounding Walnut You’ll Hear Today

November 2, 2023 by Kristina Panos 16 Comments

Do you ever find yourself eating walnuts and think, this would make a great enclosure for something like a Bluetooth speaker? That seems to be exactly what happened to [Penguin DIY].

In the mesmerizing video after the break, you’ll see [Penguin DIY] do what seems to be impossible. They start with a tiny 5 V power bank module which is still not small enough to fit, so they remove all the components and dead-bug them back together.

This is really just the beginning. There of course has to be a female USB of some type, so [Penguin DIY] Dremels out the perfect little slot for it.

They did manage to stack and fit a MH-MH18 Bluetooth audio module and an HXJ8002 mini audio amplifier module in the walnut, but of course, it took a lot of fiddly wiring to extend the LEDs and wire them up.

Then in the other half of the shell went the 4Ω 2 W mini speaker. [Penguin DIY] of course drilled a ton of little holes in the shell for the sound to come through. Also on this side are three tiny switches for play/pause and previous and next track, and the latter two can be long pressed to control the volume. Definitely check this out after the break.

Do the notifications of your Bluetooth speaker annoy you? There’s a hack for that.

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Sonos Speakers Free To Sing Again

December 15, 2022 by Chris Lott 69 Comments

Over at the EEVBlog, [Dave Jones] takes a second look at the Sonos Play 5 Gen 1 that he rescued from the dumpster recently. Despite being solidly built, [Dave] discovered that even the stereo line-in jack can’t be used without registering an account with Sonos. Not to be defeated, he hacks these speakers to make them work standalone.

Bluetooth Audio Amplifier Module (Fosi Audio)

The hack here involves fitting the speaker cabinet with new “guts” in the form of a wireless stereo 2×50 watt digital amplifier [Dave] found online for under $30. This particular model, the Fosi TB21, is almost a perfect fit for the Sonos cabinet — with only minimal Dremel tool encouragement required. It turned out the power supply section of the Sonos main board was easy to isolate. [Dave] couldn’t use the existing amplifiers, so he removed them from their power supply and re-routed the power supply to the Fosi module. He also removed the Sonos wireless interface board from the cabinet, and used an online design tool to make a simple first order Butterworth crossover network set to 2800 Hz to connect the speakers.

The new amplifier board is mounted in the shallow base of the speaker cabinet. It could have easily been oriented either way, but [Dave] chose to install it knobs-forward. This also gave him a reason to toss out the Sonos badge. The resulting modified unit looks very professional, and works well as a Bluetooth speaker for the lab.

We wrote about the opposite conversion last year, where old speakers from the 1960s were hacked to add Sonos capability. You can read about the controversy surrounding Sonos here, and we discussed the issue on the Hackaday Podcast in episode 058.

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Retro Speaker Becomes The Perfect Micro PC

October 5, 2022 by Jenny List 6 Comments

We’ve seen many cyberdecks and home built computers in our time here at Hackaday, but we’ve not seen many so tiny and so neatly built as this one from [Carter Hurd]. It takes the form of a tiny retro PC with a working display and keyboard, and we like it a lot.

The diminutive computer started life as a neat little retro themed Bluetooth speaker that a company bravely sent him for a project when he declined the chance to review it. Out came the speaker and electronics, and in went a USB Blackberry keyboard with a custom made bezel where the speaker’s keys had been.

The display is a 4″ LCD designed for a Raspberry Pi, and somewhat incredibly, he trimmed its corners to fit into the case. Making the curved CRT-style display front was achieved with vacuum form plastic, and a new display bezel was 3D printed.

A full-size Raspberry Pi fits in the base of the unit, and here he admits that it’s not the tidiest job. Perhaps a Pi Zero would have been more unobtrusive, but either way from the top and front it’s a really cute little machine. It may not be the only tiny cyberdeck we’ve seen, but it’s certainly a well-built one.

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The speaker PCB inside of the speaker, with a flash chip ZIF holder soldered to the SPI flash pads on the PCB

Bluetooth Speaker Domesticated Through Firmware Mod

June 13, 2022 by Arya Voronova 30 Comments

This might sound like a familiar problem – you get a Bluetooth speaker, and it sounds nice, but it also emits all kinds of weird sounds every now and then. [Oleg Kutkov] got himself a Sven PS460 speaker with FM radio functionality, but didn’t like that the “power on” sound was persistently loud with no respect for the volume setting, and the low battery notification sounds were bothersome. So, he disassembled the speaker, located a flash chip next to the processor, and started hacking.

Using a TL866 and minipro software, he dumped the firmware, and started probing it with binwalk. The default set of options didn’t show anything interesting, but he decided to look for sound file signatures specifically, and successfully found a collection of MP3 files! Proper extraction of these was a bit tricky, but he figured out how to get them out, and loaded the entire assortment into Audacity.

From there, he decided to merely make the annoying sounds quieter – negating the “no respect for the volume setting” aspect somewhat. After he exported the sound pack out of Audacity, the file became noticeably smaller, so he zero-padded it, and finally inserted it back into the firmware. Testing revealed that it worked just as intended! As a bonus, he replaced the “battery low” indicator sound with something that most of us would appreciate. Check out the demo video at the end of his write-up.

Domesticating your Bluetooth speakers tends to be called for. If you can’t do that for whatever reason, you can rebuild them into an audio receiver – or perhaps, build your own Bluetooth speakers, with aesthetics included and annoyance omitted from the start.

Print Your Own Wireless 2.1 Speaker System

April 29, 2021 by Lewin Day 17 Comments

Buying a set of stylish bookshelf speakers is a perfectly reasonable thing to do, and remains legal in most free countries around the world. However, if you really want to impress with a pretty pair to crank out your tunes, you might consider designing and printing your own. [EH_Design] did just that with a stylish 2.1 Bluetooth audio system.

The 2.1 designation refers to the use of two stereo channels plus a subwoofer. It’s a popular setup as human perception means it’s not as necessary to have stereo imaging for low frequency content. The build uses a Texas Instruments TPA3116D2 Class D amplifier with a Bluetooth input, with the efficient design allowing the build to be more compact without the need for as much heat sinking. A 24 V supply delivering up to 3 A is specified, providing plenty of volume when needed. The speakers themselves consist of 3″ drivers mounted in attractive 3D-printed shells, with the “subwoofer” consisting of a pair of 5″ woofers paired up in a special isobaric enclosure that enables a smaller volume to acoustically act like one double the size.

The result is a futuristic-looking set of bookshelf speakers that remind us of some of the fancier high-end sets often seen in hi-fi magazines. Of course, if 3D printing enclosures isn’t enough for you, you could always consider 3D printing the actual speaker driver itself. When you do, let us know how it goes!

ESP32 Spectrum Analyzer Taps Into Both Cores

December 10, 2020 by Tom Nardi 16 Comments

We probably don’t need to tell the average Hackaday reader that the ESP32 is a powerful and extremely flexible microcontroller. We’ve seen some incredible projects using this affordable chip over the last few years, and by the looks of it, the best is yet to come. That’s because it always takes some time before the community can really figure out how to get the most out of a piece of hardware.

Take for example the Bluetooth audio player that [squix] was recently working on. Getting the music going was no problem with the esp32-a2dp library, but when he wanted to add some visualizations the audio quality took a serious hit. Realizing that his Fast Fourier transform (FFT) code was eating up too much processor power, it seemed like a great time for him to explore using the ESP32’s second core.

[squix] had avoided poking around with the dual-core nature of the ESP32 in the past, believing that the second core was busy handling the WiFi communication. But by using the FreeRTOS queue system, he wrote some code that collects audio data with one core and runs the actual FFT magic on the other. By balancing the workload like this, he’s able to drive the array of 64 WS2812B LEDs on the front of the Icon64 seen in the video after the break.

Even if you’re not terribly interested in running your own microcontroller disco, this project may be just the example you’ve been waiting for to help get your mind wrapped around multitasking on the ESP32. If you want to master a device with this many tricks up its sleeve, you’ll need all the help you can get.

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