The electric horn of a car is produced by the vibration of a metal diaphragm. The auto electric horn is composed of Zhuan iron core, magnetic coil, contact SHU point, armature, diaphragm and so on.

When the driver presses the horn switch, electricity flows through the contact through the coil, and the coil generates magnetic force to absorb the armature, forcing the diaphragm to move.
The armature moves so that the contact is disconnected, the current is interrupted, and the coil magnetic force disappears. The diaphragm returns to its original position together with the armature under the
action of its own elasticity and the spring.

Contact closed circuit is connected again, the current through the contact through the coil to generate magnetic force, repeat the above action. This repeated cycle of diaphragm vibration,
thus issuing sound. The sound board and the diaphragm are rigidly connected, which can make the vibration sound more pleasant.