Device (36, 56, 200, 240, 270, 310, 370) for regulating the relative angular frequency (w) between a magnetic structure (4, 4A, 202, 244, 246, 4B, 316, 372) and a resonator (38, 38A, 210, 242, 312, 314, 386) magnetically coupled so as to define together an oscillator forming said regulating device, the magnetic structure comprising at least one annular magnetic track (11, 13, 11A, 13A, 204, 11A1, 328, 330, 378, 380) centred on an axis of rotation (20, 20A) of said magnetic structure or of the resonator, the magnetic structure and the resonator being arranged to rotate in relation to one another about said axis of rotation when a torque is applied to the magnetic structure or to the resonator; the resonator comprising at least one magnetic element for a magnetic coupling to said annular magnetic track, said magnetic coupling element having an active end portion (46, 46A, 46B, 262, 266, 280, 282, 325, 326) made of a first magnetic material and situated on the same side as said annular magnetic track; said annular magnetic track being made at least in part of a second magnetic material arranged such that the potential magnetic energy of the oscillator varies angularly and periodically along the annular magnetic track, thus defining an angular period (θ P) of said annular magnetic track, and such that it defines magnetically first zones (40, 42, 40A, 42A, 382) and second zones (10, 12, 10A, 12A, 206, 334, 384) angularly alternating with a first zone and an adjacent second zone in each angular period; each second zone producing, relative to an adjacent first zone, a stronger repulsion force or a weaker attraction force for any same zone of said active end portion when said any same zone is superimposed, in orthogonal projection to a general geometric surface in which the annular magnetic track extends, respectively on said second zone or on said adjacent first zone; said magnetic coupling element being magnetically coupled to said annular magnetic track such that an oscillation by a degree of freedom of a resonant mode of the resonator is maintained within a useful range for the torque applied to the magnetic structure or to the resonator and that a such period of said oscillation occurs during said relative rotation in each angular period of said annular magnetic track, the frequency of said oscillation thus determining said relative angular frequency, said degree of freedom defining an axis of oscillation of said active end portion passing through its centre of mass; said resonator being arranged relative to said magnetic structure such that said active end portion is at least for the most part superimposed in orthogonal projection on said annular magnetic track during substantially a first alternation in each period of said oscillation, and such that the course taken by the magnetic coupling element during said first alternation is substantially parallel to said general geometric surface, the annular magnetic track having in said general geometric surface a dimension along the orthogonal projection of said axis of oscillation which is greater than the dimension of said active end portion along said axis of oscillation; each of said second zones having in orthogonal projection a general contour with a first portion, defining a line of penetration (10a, 12a, 214, 336) above said second zone for said active end portion of the magnetic coupling element during said oscillation, and with a second portion defining an exit line (10b, 12b, 216) above said second zone for said active end portion during said oscillation, said exit line being oriented substantially in an angular direction parallel to a zero position circle (44, 44A) which is centred on said axis of rotation and which passes through the orthogonal projection of the centre of mass of said active end portion in its rest position; the magnetic structure also defining for the active end portion at least one exit zone which extends in said general geometric surface, said at least one exit zone receiving in orthogonal projection at least the greater part of said active end portion when it exits, during said oscillation, successively from the annular magnetic track by the respective exit lines of the second zones, said at least one exit zone producing, relative to said second zones, a weaker repulsion force or a stronger attraction force for any same zone of said active end portion when said any same zone is superimposed in orthogonal projection respectively on said at least one exit zone or on said second zones; the active end portion of said coupling element in its rest position having, in orthogonal projection in said general geometric surface, a first dimension, along a first axis perpendicular to said zero position circle and passing through the orthogonal projection of the centre of mass of said active end portion, and a second dimension, along a second axis defined by said zero position circle, which is greater than said first dimension; said exit line of each of the two zones having a length, along said at least one exit zone and along said second axis, which is greater than the first dimension of the active end portion.