Vintage Silvertone Cabinet Gets Bluetooth Treatment

July 30, 2018 by Steven Dufresne 7 Comments

This Bluetooth speaker is full of delightful surprises. The outer shell is an antique radio cabinet, but its practically empty interior is a combination of Dead Bug circuitry and modern BT receiver.

[PJ Allen] found the BT receiver on Groupon and decided to whip up amplifier and threshold detector circuits using only parts he already had in order to make this vintage-looking Bluetooth speaker. The cabinet is from a Silvertone Model 1955 circa 1936. Don’t worry, no antiques were harmed in the making of this hack, the cabinet was empty when he bought it.

The amplifiers, one per speaker, began life as a circuit from TI’s LM4871 datasheet. Some of the departures came about because he didn’t have the exact component values, even paralleling capacitors to get in the right range. The finished board is a delightful mix of “Dead Bug” and quasi-Manhattan style construction, “quasi” because he carved up the ground plane instead of laying pads on top of it.

Look at the front of the cabinet and you’ll see a rectangular display. Watch the video below and you’ll see that it throbs in time to the music. To do that he came up with a threshold detector circuit which started out based on a circuit from a Sharp/Optonica cassette tape deck, but to which he made improvements.

Not all cabinets come empty though. Check out this post by our own [Gregory L. Charvat] about restoring these wonderful old radios.

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Turn A Cheap Bluetooth Speaker Into An Audio Receiver

July 23, 2018 by Sven Gregori 16 Comments

Cheap Bluetooth speakers come in all different kinds of shapes and colors, and they let you conveniently stream music, for example from your mobile phone. For [mcmchris], they had one significant shortcoming though: while most of them come with some auxiliary input port as alternative audio source, they usually lack an audio output port that would let him route the audio to his more enjoyable big-speaker sound setup. Lucky for him, it’s a problem that can be fixed with a wire cutter and soldering iron, and so he simply turned his cheap speaker into a Bluetooth audio receiver.

After opening the speaker, [mcmchris] discovered a regular F-6188 Bluetooth audio module built around the BK8000L chip, with the audio jack connected to the chip’s aux input pins. Taking a close look at the PCB, the solution seemed obvious: cut the connection to the chip’s aux input pins, and connect the audio jack parallel to the audio signal itself. After some trial and error, the output pins of the on-board op amplifier seemed to provide the best audio signal for his shiny new output jack. You can see more details about the speaker’s inner life and a demonstration in the video after the break — in Spanish.

If the concept looks familiar to you, we’ve indeed seen a very similar approach to equip a Google Home Mini with an audio output jack before. The alternative is of course to just build a decent sized Bluetooth speaker yourself.

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Explore Low-Energy Bluetooth By Gaming

July 13, 2018 by Bryan Cockfield 5 Comments

For several years now, a more energy-efficient version of Bluetooth has been available for use in certain wireless applications, although it hasn’t always been straightforward to use. Luckily now there’s a development platform for Bluetooth Low Energy (BLE) from Texas Instruments that makes using this protocol much easier, as [Markel] demonstrates with a homebrew video game controller.

The core of the project is of course the TI Launchpad with the BLE package, which uses a 32-bit ARM microcontroller running at 48 MHz. For this project, [Markel] also uses an Educational BoosterPack MKII, another TI device which resembles an NES controller. To get everything set up, though, he does have to do some hardware modifications to get everything to work properly but in the end he has a functioning wireless video game controller that can run for an incredibly long time on just four AA batteries.

If you’re building a retro gaming console, this isn’t too bad a product to get your system off the ground using modern technology disguised as an 8-bit-era controller. If you need some inspiration beyond the design of the controller, though, we have lots of examples to explore.

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Vintage Headphones Bluetooth Conversion Goes The Extra Mile

July 9, 2018 by Ben James 2 Comments

[KaZjjW] wanted to retrofit a pair of nicely styled vintage headphones to be able to play wirelessly over Bluetooth. In principle this is an easy task: simply stick a Bluetooth audio receiver on the line-in, add a battery, and you’re all set. However, [KaZjjW] wanted to keep the aesthetic changes to the headphones at an absolute minimum, retaining the existing casing and volume control, whilst cramming the electronics entirely inside and out of sight.

With the inherent space constraints inside the cups of the headphones, this proved to be quite a challenge. The existing volume potentiometer which hung half outside the case was remounted on an ingenious hinge made of two PCBs, with the pot floating next to a surface mounted switch. This allowed it to not only control the volume, but also act as an on/off switch for the Bluetooth. The only other existing cuts in the casing were a circular hole for the audio cable, and a slit for the cable strain relief. These worked perfectly for an LED status indicator and micro-USB battery charging.

The main chip used for receiving audio over Bluetooth was the BM62 by Microchip. It’s a great all-in-one solution for this kind of project as it has built-in battery charging, an on-board DAC and audio amp, as well as a serial control interface. In part 2 of the project log, the process of programming the BM62 was documented, and it was painful – it’s a shame that the software support lets it down. But a hacker will always find a way, and we’ve seen some pretty neat hacks for reprogramming existing chips in off-the-shelf Bluetooth headphones.

Two PCBs for the pot button hinge, one for the LED and micro-USB connector, as well as one for the Bluetooth receiver and a PIC. That’s four PCBs in a pretty small space, enabled by some commendable design effort both electronically and mechanically. It certainly paid off, as the finished product looks very slick.

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Animated Bluetooth Bike Turn Signals

May 24, 2018 by Tom Nardi 40 Comments

Tired of risking his life every time he had to signal a turn using his hands while riding his bicycle in rainy Vancouver, [Simon Wong] decided he needed something a bit higher tech. But rather than buy something off the shelf, he decided to make it into his first serious Arduino project. Given the final results and the laundry list of features, we’d say he really knocked this one out of the park. If this is him getting started, we’re very keen to see where he goes from here.

So what makes these turn signals so special? Well for one, he wanted to make it so nobody would try to steal his setup. He wanted the main signal to be easily removable so he could take it inside, and the controls to be so well-integrated into the bike that they wouldn’t be obvious. In the end he managed to stuff a battery pack, Arduino Nano, and an HC-05 module inside the handlebars; with just a switch protruding from the very end to hint that everything wasn’t stock.

On the other side, a ATMEGA328P microcontroller along with another HC-05 drives two 8×8 LED matrices with MAX7219 controllers. Everything is powered by a 18650 lithium-ion battery with a 134N3P module to bring it up to 5 VDC. To make the device easily removable, as well as keep the elements out, all the hardware is enclosed in a commercial waterproof case. As a final touch, [Simon] added a Qi wireless charging receiver to the mix so he could just pull the signal off and drop it on a charging pad without needing to open it up.

It’s been some time since we’ve seen a bike turn signal build, so it’s nice to see one done with a bit more modern hardware. But the real question: will he be donning a lighted helmet for added safety?

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Cracking A Bluetooth Credit Card

April 8, 2018 by Tom Nardi 44 Comments

You might be surprised to find out that it’s actually not a good idea to put all of your credit card information on a little Bluetooth enabled device in your pocket. Oh, what’s that? You knew already? Well in that case you won’t find the following information terribly shocking, but it’s still a fascinating look at how security researchers systematically break down a device in an effort to find the chinks in its armor.

[Mike Ryan] of ICE9 Consulting has recently published an article detailing the work done to examine and ultimately defeat the security on the FUZE Card. From using an x-ray machine to do non-destructive reconnaissance on the device’s internals to methodically discovering all the commands it responds to over Bluetooth, it’s safe to say the FUZE Card is cracked wide open at this point.

To be clear, the attacker must still pair with FUZE, so physical access is required. But as pointed out by [Mike] in the blog post, handing your card over to a merchant is standard operating procedure in many cases. It isn’t as if it would be hard to get a hold of one of these FUZE cards for a minute or two without the owner becoming suspicious. Pairing FUZE to the Linux device to continue to the next step of the attack only takes a few seconds, as demonstrated in the video after the break.

Once paired, the attacker can simply send a BLE command to FUZE which disables the lock screen. It’s really that simple. The attacker can also send commands to dump credit card info over Bluetooth, meaning they could download your information even when the card is “safely” back in your pocket. The inherent failure in the FUZE design is that you don’t need to provide any sort of authentication to pair it to a new Bluetooth device. It makes the (very dangerous) assumption that the person holding it is entitled to do so.

Even if you know better than to ever buy a device like this, the post [Mike] has written up is really a must-read for anyone who’s ever looked at a device and tried to figure out what was going on in its little silicon brain. We especially liked his assertion that reverse engineering a device essentially boils down to: “staring, thinking, a little experimentation, but mostly staring and thinking.” We’re having an internal debate here at Hackaday HQ about making that the site’s tagline.

Incidentally, this is very similar to the Bluetooth gun “safe” that was cracked not so long ago. At this point, it might be wise to just stay away from anything with that little blue logo on it if you intend to trust it with your identity and/or deadly weapon.

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Sharpening With Bluetooth

March 31, 2018 by Al Williams 21 Comments

Few things are as frustrating in the kitchen as a dull knife. [Becky] and her chef friend collaborated to build a Bluetooth module to tell you when you are sharpening a knife at the optimum angle. That might sound a little specialized, but the problem boils down to one that is common enough in a lot of situations: how do you tell your exact orientation while in motion? That is, with the knife moving rapidly back and forth over the sharpening stone, how can you measure the angle of the blade reliably?

Looking for a challenge, [Becky’s] first attempt was to just use an accelerometer. It worked, but it wasn’t very precise. Her final answer turned out to be a full inertial measurement unit — the BNO055 — that combines an accelerometer, a magnetometer, and a gyroscope along with enough smarts to fuse the data into actual position data.

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