Remember the good ol’ days when the rotary dial was all there was? When your finger could potentially slip from its notch mid-dial and you’d have to hang up and start all over again? You can experience the soothing chatter of a rotary encoder sending out your digits by building a Bluetooth rotary dial for your cell phone.
Paweł Zadrożniak wrote in to show us how he built a functioning rotary dial for his cell phone. The project isn’t very complex, you only really need three pieces: the rotary dial, a Nordic Semiconductor NRF51 DK board, and a battery.
He has released the code so that you could pull this off by yourself. If you don’t have access to the NRF51 DK board, you should be able to pull off the same thing with any Bluetooth capable dev board. The rotary dial simply generates a pulse that you can interpret as a key press.
As you can see in the video, it is cumbersome and inefficient, exactly as Zadrożniak planned. He jokes about this being a hipster dialer for his phone and even went with the hipster vibe for his battery choice.
The board could be powered from a 3V coin cell battery, but I have connected a large, flat, 4.5V battery because small coin batteries are not hipster enough!