Quantum Rotary Dial Is a Vintage Rotary Telephone That Controls Your Computer

Digital technology was still in its infancy in the 1960s and 1970s, but telephones have existed for much longer than that. In the early days, people would have to speak to an operator when making a call and that operator would patch them through to the correct line. But for a while, you could make calls by dialing on phones that were completely electromechanical. Rotary dials made that possible by sending timed pulses corresponding to numbers, which could be understood by automated switchboards. Today they’re mostly obsolete, but you can follow Nathan Cooke’s lead to convert a vintage rotary telephone into an input device for your computer.

If this sounds familiar, that is because Cooke was partially inspired by my own Rotary Phone Dial Volume Control project from last year. For that project, I only kept the dial mechanism from a vintage rotary phone and housed it within a simple 3D-printed enclosure. Cooke wanted to keep the original phone intact, but wanted it to connect to his computer in a similar way. The Python script I wrote for my project had only one function: changing the volume of the programs running on my computer. Cooke’s script has multiple modes and can do so much more. Dialing 1 will put it into numpad mode, so he can type numbers. Dialing 2 puts it into alpha mode, which allows text to be entered in a manner similar to T9. It can also switch between apps and control Alfred (a productivity app) workflows.

Reading a rotary phone dial is really easy with a microcontroller. The dial is essentially just a spring-loaded switch that makes contact as it spins past each number. All you need to do is count the number of pulses that are made each time the switch makes contact. Cooke used an Arduino Nano board for the job and that sends the dialed number to the computer over the USB serial connection. After removing some of the unused hardware from the inside of his rotary phone, Cooke had plenty of room inside of the enclosure for the Arduino and the perboard it is soldered onto. From the outside, the rotary phone looks completely original. After the Arduino sends a number to the computer, Cooke’s open source Quantum Rotary Dial Python script handles the rest of the functionality. He even integrated a handy status bar icon, so you can easily see which of the available modes you’re currently using. If you want to make use of a rotary phone in a cool way, I highly recommend that you take a look at this project.