Alastair Aitchison's Vintage Telephone Hides a Teensy 4.0-Powered Audio-Recording Wedding Guestbook

YouTuber Alastair Aitchison, of Playful Technology, has shown off a new project designed to be a hit at a wedding, birthday, bar mitzvah, or other celebratory gathering: a converted vintage telephone that acts as an audio-based guestbook.

"I think a lot of Arduino projects have too much emphasis on the 'visual' side of things — LEDs, NeoPixels, LCD displays, etc., etc.," Aitchison explains of the inspiration behind his latest creation, "and there seems to be comparatively much less audio projects. So, here's a tutorial I just made on how to create an 'Audio Guestbook' from an old telephone."

The project is driven by a Teensy 4.0 microcontroller board, linked to an Audio Shield add-on and with a microSD card for storage. The hardware itself is then housed in the body of a vintage telephone, using the handset as speaker and microphone.

When a guest lifts the handset, a pre-recorded message is loaded from the microSD card and played through the speaker; once playback has finished, the build swaps into recording mode and captures the microphone input as a 16-bit 44.1kHz WAV file. Each recording is incrementally numbered — meaning that, by the end of the gathering, the microSD should be filled with individual messages of well-wishing.

"I'm aware of a couple of companies that offer these kind of products — 'After the Tone,' 'FêteFone,' 'Life on Record,' 'At the Beep,' and others," Aitchison admits, "but they typically cost ~$400 to hire the equipment, and then additional charges to obtain copies of the audio files afterwards! The guestbook I've built cost about £30 [around $38] to make."

The full guide, including links to all required hardware and software, is now available on the Playful Technology YouTube channel.