Under command from the Arduino, the relay normally routes signals from the stock microcontroller to the signal processor, allowing the normal control of volume and other features.

Bluetooth does nothing new. Even before the technology was introduced, you could make hands-free calls to Mum and stream Mobb Deep’s The Infamous through your car stereo. Bluetooth’s crowning ...

But in almost every used car, there's a way to make Bluetooth connectivity work. It just depends on what era your car comes from, how much you care about audio quality, and what your budget is.

This one’s a long shot, but it’s possible that your car’s system—whatever it uses to make Bluetooth work—has some kind of update that will restore the functionality you no longer have.

John Boxall, author of the new book Arduino Workshop, shares a few of the projects from his book on how to get started with the microcontroller. (Click the links to see PDFs of the complete ...

Why buy a Bluetooth speaker when you can make one out of just about anything—and that perfectly fits your style?