A drivetrain assembly (100, 200) for a personal care device (10), the drivetrain assembly including a resonator (110) connected to a transmission component (24) configured to transmit oscillations to the removable attachment； and a drive coil (120) configured to oscillate the resonator in a first direction； where the drive coil is configured to generate an installation or removal signal in response to installation or removal of the removable attachment, the installation or removal of the removable attachment generating movement of the resonator in a second direction； and where the drivetrain assembly is configured to communicate the generated signal to a controller.
