AirPod: Standalone FM Earbud

Earlier in this series, a compact FM radio was created using a touch display.

- ASHWINI KUMAR SINHA

From there, the design moved forward with an FM radio integrated into an earbud—though that version had a limitation: the earbud had to be reprogrammed each time the channel needed to be changed. Now, the design journey continues with a fully standalone FM earbud that no longer relies on an external MCU for channel selection or other functions. In this version, both the MCU and user interface are built entirely into the earbud itself.

This is the smallest working system in the series so far. That said, it does require surface-mount soldering experience. A compact MCU and single-switch interface allow users to switch FM channels (up/down) and adjust volume. The design is compact enough to fit within an earbud, but the battery capacity remains limited, restricting extended listening time. With some reconfiguration, the earbud cavity can be modified to accommodate a larger battery.

For better reception, an external or SMD antenna can also be integrated into the system. In the current version, a simple wire coil has been used inside the earbud to act as an antenna, avoiding the need for external components while keeping the design ultra-compact.

Bill of materials

Component selection is critical, as the entire FM radio must fit inside the earbud. Ultra-compact parts are required, with the MCU and FM module being key. As in the earlier design, the RDA5807 FM module has been used, one of the smallest available. It communicates via I2C, allowing channel changes, volume control, and station scanning, all managed through an MCU.