How does a horn work?

Horn of a motorcycle

In this post, we will try to understand the working of horns. Horns are electrical equipment which produces sound. They utilize the combination of electromagnet and diaphragm to produce sound. You might be aware of the fact that a metallic sheet vibrating at high frequency produces sound. The same phenomenon is utilized in a horn. The vibrating diaphragm produces a sound which we listen as the horn sound. Now let's understand the working of a horn in detail.

    Working of horn

    A horn generally consists of following parts.
    1. Electromagnet
    2. Diaphragm
    3. Contact plates
    4. Plunger

    The main component of the horn is the diaphragm. It is a thin metallic circular sheet or membrane which vibrates to produce sound. It lies at the front of the horn assembly and is connected to a plunger. The plunger faces towards the electromagnet. 

    The electromagnet lies at the rear end of the horn assembly.  The current is supplied to one end of an electromagnet from the positive terminal of the battery and its other end is earthed to the frame body through the contact plate arrangement. 

    Circuit diagram of a motorcycle horn

    The frame body is connected to the negative terminal of the battery and hence is called earth. Hence, connecting the second terminal of the horn to the frame completes the current flow circuit. The two contact plates which contain two small points of contact are connected to each other in the default state. A contact braking disk is fitted on the plunger and it lies in between the contact plates, as shown in the figure.  As soon as we press the horn switch, the current starts flowing in the electromagnet through the contact points. This magnetize the electromagnet which attracts the plunger towards it. The plunger pulls the diaphragm with it and hence the diaphragm moves inside. As the plunger is pulled inside, the contact breaker disc pushes the contact plates apart and hence the current supply to the electromagnet stops. In absence of magnetic attraction, the diaphragm springs back to its original position. This pulls the plunger and the disc to their original position and the contact between the contact points is restored. So the current once again starts flowing through the electromagnet and the whole process is repeated again and again. During all this, the diaphragm continues it's to and fro motion. This induced vibrations in it, which produces the sound of a definite frequency. As soon as we release the horn switch, the current flow to electromagnet stops and hence the horn sound stops.

    Also read: Fuel injection System

    So this was all about the working of an electric horn. I hope you liked it. Please subscribe to our blog to receive all our articles through the mail.
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