A simple piano doorbell that replaces the usual chime with real piano notes was demonstrated in a recent project published by Arpan Mondal. The system combines microcontroller-based control with audio playback to create an interactive doorbell.
At its core is an ESP32-S3, which takes inputs from 5 keys styled like a tiny piano. Each key is built using micro limit switches and connected through a resistor ladder circuit, letting the controller gauge the key that’s pressed based on distinct voltage levels. A PAM8403 audio amplifier module drives a speaker to output sound. The build embeds the audio directly into the microcontroller’s program. Sound files are processed into .raw format, converted into C header files, and included in the firmware.
The keys as well as the housing are 3D-printed in PLA and painted to resemble a piano. The assembly has two main parts: the outdoor piano interface and a speaker indoors connected via wiring. The device is powered by a 5V DC source. The project highlights a practical use of resistor ladders for input multiplexing, digital audio playback via a microcontroller, and basic audio signal amplification. The creator noted, “And the connecting wire between the indoor and outdoor units is another area I'd like to refine – a truly wireless solution remains the ultimate goal”.
