A mechanical oscillator, formed of a mechanical resonator and a device for maintaining oscillation, and an auxiliary oscillator forming a reference time base including a synchronisation device arranged to slave the medium frequency of the mechanical oscillator on that of the auxiliary oscillator. The synchronisation device includes an electromagnetic braking device which is formed of a coil and at least one permanent magnet and arranged such that an induced voltage is generated between the terminals of the coil in each alternation of the oscillation of the mechanical resonator. The synchronisation device is arranged to be able to reduce momentarily the impedance between the terminals of the coil during distinct time intervals, any two successive time intervals exhibiting between the respective starts thereof a time distance substantially equal to a positive whole number multiplied by half of a set-point period for the mechanical oscillator.

A horological movement provided with a generator and a circuit for regulating the frequency of rotation of this generator, the regulation circuit being arranged to be able to detect the zero crossings of an induced voltage generated in the stator by the rotating rotor and to generate first braking pulses which are triggered after zero crossings and each end before the induced voltage reaches a peak value, preferably before the rectified induced voltage reaches a power supply voltage provided by a power supply capacity. In addition, the regulation circuit is arranged so as to be able to further generate second braking pulses each of which occurs after detection of the end of a charging period of the power supply capacity during which the induced voltage reaches a peak value and each end before the induced voltage crosses zero.

A horological movement provided with a generator and a circuit for regulating the frequency of rotation of this generator, the regulation circuit being arranged to be able to detect the zero crossings of an induced voltage generated in the stator by the rotating rotor and to generate first braking pulses which are triggered after zero crossings and each end before the induced voltage reaches a peak value, preferably before the rectified induced voltage reaches a power supply voltage provided by a power supply capacity. In addition, the regulation circuit is arranged so as to be able to further generate second braking pulses each of which occurs after detection of the end of a charging period of the power supply capacity during which the induced voltage reaches a peak value and each end before the induced voltage crosses zero.

A mechanical oscillator, formed of a mechanical resonator and a device for maintaining oscillation, and an auxiliary oscillator forming a reference time base including a synchronisation device arranged to slave the medium frequency of the mechanical oscillator on that of the auxiliary oscillator. The synchronisation device includes an electromagnetic braking device which is formed of a coil and at least one permanent magnet and arranged such that an induced voltage is generated between the terminals of the coil in each alternation of the oscillation of the mechanical resonator. The synchronisation device is arranged to be able to reduce momentarily the impedance between the terminals of the coil during distinct time intervals, any two successive time intervals exhibiting between the respective starts thereof a time distance substantially equal to a positive whole number multiplied by half of a set-point period for the mechanical oscillator.