technical information about electric horn?

Answer 1

From your sketchy question I'm guessing you are asking how an electric horn works. A simple electric horn is a buzzer with an attached diaphragm to emit a louder sound. When it is turned on, electric current flows through a pair of contacts (one movable and the other stationary) and through an electromagnet. The electromagnet pulls a soft iron slug toward it. The slug is attached to a diaphragm which converts the motion to a loud sound, and is also attached to the movable contact. The motion in the pulling direction opens the contacts and breaks the current flow to the electromagnet, which then releases the slug. The slug is returned to its original position by a spring. This closes the contacts and a new cycle begins. About 50 to 300 of these cycles occur each second, so the diaphragm emits a fundamental at that frequency plus numerous strong harmonics which give it its characteristic (attention-getting and usually annoyng) sound.