The vibrating switch consists of a small bar of soft iron which has one end near the core of the upper coil and lies on that of the lower coil, supported by two pins. It is pushed by a flexible steel reed on which the point of a screw acts to regulate the pressure on it.
The contacts are on the face of the vibrating reed and on a steel reed which is fixed at the bottom to a vertical brass support and is regulated by a screw the point of which lies on the steel reed.