[Dan] had been wanting a pair of Bluetooth headphones for quite a while. Most of the reviews for wireless headphones in the $50-$80 range complained of tinny sound and dropped bass. Nevertheless, he stumbled upon a $20 pair of headphones with similar reviews and realized that he could switch out the driver and make a decent pair of cans.

The donor drivers came from a pair of Sennheiser HD 540 headphones. These are very respectable headphone speakers that cost about what you would expect for pro audio gear. To to get Bluetooth working with the Sennheisers, [Dan] removed the PCB and battery enclosure and attached them to the headband with velcro.

For his build, he had to cut the cable on the Sennheisers and solder them to the Bluetooth board. There was never any danger of ruining a good pair of headphones, though. If he screwed up he was only out a headphone cable. Now [Dan] has a nice pair of Bluetooth headphones that can reproduce bass. Not a bad deal for a $20 pair of headphones.

[MarkoeZ] had an issue with keys breaking off in his door lock, and while normal people might try to simply replace the lock all together, [MarkoeZ] decided to do it the “Hackaday” way by adding a bluetooth lock to his door. His door is already setup where someone can walk up to it, page an internal intercom and have someone buzz you in. From the inside the intercom was modded with a TI Launchpad with a “deal extreme” bluetooth module and relay.

Access is granted by the use of an android phone running “BT_Serial_Tester” which is a simple app that allows you to send characters over bluetooth. Just enter a pin, grab the door before the buzzer times out, and you’re in! A starting point for the MSP code and schematics are available on his blog. Join us after the break for a quick demonstration video.

When [trandi]‘s wife saw a cute night light at Ikea, she had to have it. She actually bought several of these for when her husband would inevitably crack one open and start tinkering with the microcontroller inside. The inevitable hack is pretty cool, and also gives us some ideas for interfacing with Android on the cheap.

The build started as an Ikea Spoka night light, an adorable anthropomorphized night light with a squishy silicone skin. Inside the Spoka are a dozen tri-color LEDs that [trandi] can cycle through with the push of a button. After deciding to control the lights inside the Spoka with an Android phone he reached for an IOIO Android breakout board. Fate intervened and [trandi] ended up with a ridiculously cheap Bluetooth modules that provides a simple serial connection to other Bluetooth devices.

The build reuses the blue, red, orange LEDs in the night light but replaces the no-name 8-pin micro with an ATtiny2313. [Trandi] wrote a small Android app to control the color over a Bluetooth serial connection. Check out his demo after the break.

We love the extra touches that [Andrianakis Haris] added to his two-zone electronic thermometer. It includes features that you just wouldn’t find on a mass-market commercial product because of issues like added cost. For example, you can see that the PCB juts up above the LCD display, allowing the module to be mounted on a pair of screws thanks to the keyhole shape that was drilled in the substrate. I increases the board size greatly, but on a small hobby run this won’t usually affect the price of the board depending on the fab house pricing model.

The design uses an ATmega8 microcontroller to monitor sensors in two different places. There is an onboard LM35 temperature sensor for monitoring the space where the unit resides. A remote sensor module uses a DHT-11 chip to gather data about temperature and humidity. That sensor is wired, but there is one wireless option for the device. Data can be pulled down from it via an optional Bluetooth module which can be soldered to a footprint on the back of the board.

Check out the video after the break to see temperature readings pulled down wirelessly.

[Ytai Ben-Tsvi] wrote in to share a little holiday project that he and friend [Al Linke] put together, a dynamic light display that takes its cues from his Android-powered smartphone.

The display fits in a vase that sits in [Ytai’s] family room, and while it wasn’t exactly cheap to build, it sure looks nice. The vase is full of feathery decorative bits which help hide an addressable RGB LED strip. The lights are controlled by an IOIO board which the pair tucked away inside the vase as well.

The IOIO board was also fitted with a USB Bluetooth dongle, allowing it to communicate with just about any handset running a relatively recent flavor of the Android OS. When connected, the phone samples its surroundings with the onboard camera, commanding the vase to mix the colors seen by the phone into its twinkling display.

As you can see in the video below it works pretty well when used with solid, brightly colored objects. While just a fun toy in its current form, [Ytai] and [Al] have more than a few ideas on how to expand its usability.

Back in the days of yore when hats were fashionable and color TV didn’t exist, there were real life people who would answer the phone if you dialed 0. These operators would provide directory assistance, and connect you to another number (such as KL5-8635). Apple’s Siri is a lot like an olde-timey phone operator, so [davis] decided to put Siri in an old rotary telephone.

The build started off with a very inexpensive Bluetooth headset and very old rotary phone. The single button on the Bluetooth headset was wired to a contact of the dial – in this case, the number 1. Dialing 1 shorts two contacts in the phone and the Bluetooth headset turns on.

[davis] came up with a very easy build but dialing 1 just isn’t the same as dialing 0. Connecting the Bluetooth button to 0 closes the button for too long. He says ’0 for operator’ could be implemented with an ATtiny or similar, but we’re wondering if [davis] could make due with a dial-less candlestick phone.

This tiny line-following robot is quite impressive. It’s [Ondrej Stanek's] second take on the design, which he calls PocketBot 2. Just like the earlier version, this robot is small enough to fit in a matchbox, but it’s received several upgrades in this iteration.

The coin cells that ran the previous version have been replaced by a rechargeable Lithium Ion cell. The ATmega8 which controlled the first robot has been swapped out for an ATmega128 running at 32 MHz. You won’t find an IR receiver on this one either, it’s been traded for a Bluetooth module which adds a quantum leap in functionality. For instance, the graph in the upper left of this photograph shows the reflective sensor data readings used to follow the line.

There’s all kinds of great engineering in this design, which is shown off in the video after the break. One of our favorite parts is that the axles are attracted to the center of the robot by one rare-earth magnet. This keeps the rubber tires pressed against the motor spindles rather than use a gearing system.

[Travis Goodspeed] wrote in to tell us about his work reverse engineering the Bluetooth communications on this SPOT module. He’s targeted the post as a general guide to sniffing Bluetooth transmissions, but was inspired to use the SPOT as an example after seeing this other SPOT hack. We know he’s a fan of getting things to work with his Nokia N900, and that’s exactly where he ended up with the project.

This module was manufactured to be controlled by an Android phone. But there’s no control app available for the Nokia handset. Since Android uses the open-source Bluez package for the Bluetooth protocol, it’s actually pretty easy to get your hands on the packets. After grabbing a few test sets he shows how he deciphered the packets, then wrote a quick Python script to test out his findings. After working his way through the various commands available (grabbing the SPOT serial number, getting position data from it, etc) [Travis] wrote up a frontend in QT mobility for use on the N900.

Want that 70″ LCD television in your living room to be an Android device? This little guy can make it happen. With an HDMI port on one end, and a USB plug on the other for power, just plug in FXI Technologies’ Cotton Candy dongle to create a 1080p Android television.

The price isn’t set for the device, but it’s expected to be available at less than $200. Considering what’s inside that’s pretty reasonable. There’s a dual-core 1.2 GHz ARM processor, 1 gig of RAM, 64 gigs of storage, Bluetooth, WiFi, and a microSD card slot. Wow!

So is it hackable? Absolutely. Well, kind of? The company doesn’t intend to bring Cotton Candy to the retail market. Instead, they will sell the device to developers who may do what they wish. From there, said developers have the option to license the technology for their own products. This begs the question, will the development kit come in under $200? Hard to say.

Check out the video after the break to hear an interview with the company’s CEO. It certainly sounds fascinating, and like the Chumby NeTV, we can’t wait to see what comes of this.

[Thanks Adam via RootzWiki]

[Anthony Pray] had his car stereo stolen. When thinking about replacing it he realized the he and his wife never used it for anything other than an Auxiliary connection to play songs from their cellphones. So instead of buying a head unit he pulled an unused home audio amplifier out of a dark corner of his house and wired it to the car speakers. Problem solved, except that the under-dash installation meant the only volume control is on the phone playing the audio. He decided to build a wireless audio controller that would let him send commands to the phone without quite as much distraction from the road.

The device you see above is his creation. What a beauty. But seriously, it’s so random and hacked together how can you not love it? And, it works!

The frame is made from plastic coat hangers, and the wheel is an old RC control knob. There’s even a play/pause feature built from the clicking properties of a retractable ball-point pen. A Cypress PSoC board reads the knob and pen positions, then pushes commands via a Bluetooth module in order to control the phone. He recorded a testing video (after the break) which gives you a better look at the functionality of this setup.

[Ytai], the lead developer for the IOIO breakout board for the Android Open Accessory kit, figured out how to control just about anything from an Android phone wirelessly over Bluetooth.

When [Ytai] first announced the IOIO breakout board for Android devices, one of the commentors on his post said a standard Bluetooth dongle could stand in for the USB cable between the phone and the IOIO. Wireless control of home automation project and robots was just too good of an idea to let go, so [Ytai] dove into this new Bluetooth project.

After getting a cheap Bluetooth dongle from DealExtreme, [Ytai] found btstack, a lightweight Bluetooth stack that was perfect for an embedded environment. Dealing with the USB driver for a no-name Bluetooth adapter didn’t come as easily, but after a few long nights, [Ytai] emerged victorious.

He still has a few more problems to overcome. Namely, supporting environments where more than IOIO board is available. [Ytai] is thinking about adding support for WiFi dongles, something we’d love to see. Check out [Ytai]‘s demo of wireless control of a servo after the break.

[Sean] happened to have an extra Android phone sitting around and wanted to see what type of home automation he could use it for. One simple hardware modification, and some apps from the Android Market let him monitor and control his garage door remotely.

The hardware modification is a hack we’ve already looked at. The BTmate uses a Bluetooth headset with an added transistor to short the connections on your garage door opener. The only issue is that you need to be within range for the Bluetooth to work. [Sean] adds a layer of abstraction by using two Android phones. One is permanently mounted in the garage and handles the Bluetooth connectivity, while the other uses VNC to tunnel in anywhere he has an Internet connection.

But why stop there? He knew that this one feature was overkill, and added a second which the phone was perfect for. Since it has its own camera, he used the tinyCam app to create a webcam server. This even allows him to turn the LED on and off for a better view in dim light conditions. See [Sean's] demonstration after the break.

Overkill? Maybe, but if you’ve got a phone with a broken LCD, this might be just the thing to give it a new purpose.

It’s been a while since we checked in on [Travis Goodspeed]. His latest post makes RF sniffing with the Next HOPE badge more portable by ditching the need to display data on a computer. He’s built on the work he did at the beginning of the year, replacing the FTDI chip on the badge with a Bluetooth module. Now he can use his Nokia N900 as a GoodFET terminal to not only display the packets pulled from the air, but the control the badge as well.

Previously, the client running on the computer was communicating with the badge via a serial connection. To get it working on the N900 [Travis] transitioned from using py-serial over to using py-bluez. All of the code changes are available from the GoodFET repository.

He’s got a few other tricks planned for this concept. He put in a parts order to add Bluetooth to the Girltech IM-ME. The pretty pink pager has the same radio chip on board, so adding Bluetooth connectivity will allow it to be used in the same way. There are also plans in the works to add a couple other packet sniffing protocols to the bag of tricks, including ZigBee.

[James] is one of those guys on a quest to control everything with one device. His tool of choice is an Android phone, which can do quite a lot right out of the box. But he was never satisfied with its lack of IR remote control abilities. He fixed that feature-gap by building a Bluetooth to Infrared translator.

The hardware he used for the prototype is quite simple. A cheap serial Bluetooth modem from eBay lets him connect to his phone. An Arduino board listens for data from the modem and converts incoming commands to flashes on an IR LED. Voila, he can control the tube with his phone.

We love the potential of this hack. The Bluetooth module runs from 3.3V, and reading serial data and flashing an LED is extremely simple. You should be able to use a small uC, say an ATtiny13, and a 3.3V regulator to miniaturize the module. We could see this plugging into the USB port on the back of a TV for power, with a wire extension to put the LED into position. The only shortfall is the inability to turn the TV on remotely when drawing power this way.

Remote codes aren’t particularly large to store either. So this would be pretty easy to extend to full control of all IR-compatible home entertainment devices. You just need a tool to discover the remote control codes.

[Oscar] shows us how to use a Processing sketch for Android to communicate with Bluetooth devices (translated). It turns out this is easier than you might think. Processing and Android are both closely related to Java, and you can just import the Android libraries that deal with Bluetooth within the Processing sketch. That makes it easy to enable the Bluetooth modem when the sketch is launched, and manages connecting with devices as well as sending and receiving data.

For this example [Oscar] is using an Arduino with a Bluetooth module as a test device. His sketch first shows what devices are available, then connects to the one you select from the list. The 11 lines of Arduino code transmit a value via the serial port, and listens back for a command to toggle the LED on pin 13. [Oscar] takes time in his tutorial to show us how each step of the Processing sketch is assembled, instead of only posting the finished code.

[Thanks Sara]