The present disclosure relates to an electronic apparatus (1) for emitting electromagnetic radio-frequency or ultrasonic waves, which comprises an electronic device (2) configured to emit a frequency-variable signal (S), and a handpiece (3) connected to the terminals (21) of the electronic device (2) to receive the frequency-variable signal (S), to thereby emit a radio-frequency or ultrasonic wave the electronic device (2) comprises a control and monitoring unit (4) for scanning a range of frequencies of the frequency-variable signal (S) during a first time interval, and an electric quantity reader (5, 7) for detecting the electric current (I) and/or the voltage (V) circulating at the terminals (21), the control and monitoring unit (4) being configured to identify a maximum value for the electric current (I) and/or the voltage (V) and to associate it with a resonance frequency value, to generate the frequency-variable signal (S), during a second time interval, at the resonance frequency value.
