In common with all mechanical sonneries, the mechanism is powered by a spring barrel. If such a barrel were to be simply connected to a sonnerie, the effect of diminishing spring force would be a slowing in the pace of the musical sounding as the barrel is discharged. The common method for combating this phenomenon is to construct a regulator which is inserted in the train powering the sonnerie. However, a regulator which is constructed with spinning components emits sound of its own which would intrude on the melody of the sonnerie. To overcome this drawback, Breguet invented a silent regulator, using a technology never before brought to production mechanical wristwatches : magnets.
The rotating arms of the regulator are made of metal and are surrounded by static magnets in the exterior circumference of the regulator. As the metallic arms rotate in this magnetic environment, they produce an electrical field, which as it builds, is resisted by the magnetic field from the magnets. The faster the rotation, the greater the resistance and, correspondingly, the slower the rotation the lower the resistance. The result of all of this is a device that produces constant rotation, since both speeding up and slowing down are met with an alteration of the resistance to rotation opposite that of the change.
In other words, centrifugal force moves the silver disks of the regulator outward and more directly under the magnets, tending to slow down the rotation. At a slower speed, the springs pull the disks inward, tending to allow rotation to speed up.