The Rotary Phone Pensieve is an interactive art project that revitalizes a vintage rotary phone with a modern microcontroller, enabling it to record, save, and playback audio. When someone picks up the phone, they hear an audio prompt that invites them to share a story and/or listen to others’ responses. This simple act becomes a powerful form of engagement that blends design, sound, and storytelling. This project was exhibited at TEDxVictoria 2025 and Otherworld 2025; and made possible with support from Kindle Arts Society.
Problem
Often, conversation falls into predictable, surface-level patterns, especially at public events or work mixers. It becomes easy to engage, but without reaching anything meaningful.
What is missing is a form of prompt or invitation that gently breaks the ice. These prompts could offer permission and invite stories that are not typically shared. They open space for slightly uncomfortable or unnatural questions that require privacy and intention to surface. Additionally, many forms of communication lack space to pause and listen, causing spoken storytelling to be lost in the noise.
Rotary Phone Pensieve aims to address this gap by creating a space that invites people to share, to listen to others, and to record stories through spoken word.
Action
This project is realized by hacking the components of a rotary phone, understanding how they work, and connecting them to a microcontroller. Two second-hand rotary phones are used as well as a microcontroller for each: a Teensy 4.0 with an audio shield.
Hacking the Rotary Phone
In order for the rotary phone to function, the microphone, speaker, rotary dial, phone hook, and ringer need to be controlled. The microphone, speaker, and phone hook, and their respective wires, are straight forward to identify and easy to control with the microcontroller. The rotary dial and the ringer are a bit more difficult.
The rotary dial has three wires, each with a different signal from a mechanical switch depending on where the dial is situated. Only two of the wires were used, one which signals if the dial is at rest and the other that pulses twice for each number that rotates. So, when the rotary dial is turned to a number, one wire signals to the microcontroller that dialing has begun. As the dial is released and returns to its resting position, the microcontroller counts the pulses on a second wire, continuing until the first wire indicates the dial has come to rest. The number of pulses is divided by two (two pulses per number) to determine the dialed number. One challenge is carefully calibrating how often the microcontroller checks the second wire: sampling too quickly can introduce debounce issues and false positives, while sampling too slowly risks missing pulses altogether, resulting in false negatives.
The rotary phone’s original mechanical ringer uses a solenoid actuator to ring bells. The actuator could not be powered by Teensy 4.0 so it is removed and replaced with a servo motor and a custom-designed laser cut frame so that is can physically strike the original bells and preserve the vintage sounding ring.
All of the components such as the microcontroller, wiring, and mechanical modifications are entirely concealed within the phone to maintain the nostalgic illusion.
Code
The code is designed for functionality and to offer a logical user experience. Picking up the handset triggers the prompt and guides the user to dial ‘1’ to listen to the next community recording, ‘2’ to record their own story, or ‘0’ for the operator. There is also a secret dial code, allowing for on-site maintenance such as recording new system prompts or deleting participant recordings.
Results
This art exhibit received a ton of positive feedback. It was exhibited at TEDxVictoria 2025, Otherworld 2025, and utilized at three weddings. It has offered many stories and here are a couple that I can share:
Prompt
