A mechanical vibration switch having a magnet connected to a bar that rotates about an axis, an inertial mass connected to the bar, a magnetic material part disposed in a predetermined spaced apart relation from the magnet, a spring, a stop, and an electrical relay mechanically actuated by the bar. The magnetic material part is adjusted parallel to the magnet such that the magnetic force varies approximately linearly with the common surface area S between the face of the magnet and the face of the magnetic material part.