A timepiece includes a mechanical movement with a mechanical oscillator and an electronic device for regulating the medium frequency of this mechanical oscillator. It includes an electromagnetic transducer and an electric converter which includes a power supply capacitor for powering the regulation circuit. The electromagnetic transducer is arranged to supply a voltage signal exhibiting first voltage lobes in first half-alternations and second voltage lobes in second half-alternations of the oscillations of the mechanical oscillator. The regulating device includes a load pump arranged to store momentarily electric loads which are extracted selectively in different time zones according to a time drift detected in the functioning of the mechanical oscillator relative to an auxiliary oscillator, particularly quartz-based. The electric loads extracted are rendered after a certain delay to the power supply capacitor also according to the time drift detected.