Not only in a car, but in the electronic circuit of any equipment and facility, the function of a relay is to control large current or high voltage by small voltage or small current, but it does not have the effect of increasing the current or voltage; it acts as a switch; at small current or at the same time, it can be used as a switch. Under the control of low voltage, the other pairs (or pairs) of the larger contacts are connected (or disconnected, in the relay, the terminology is called often closed, often open contacts); the purpose is to allow large current or high voltage to drive the back load. The car horn relay is also the same, when the button on the steering wheel is pressed, the coil of the relay is connected, the electric current is drawn and the electromagnet is sucked and the contact, contact contact, the connection of the car horn circuit, the car horn work - - out sound.
This is the main function of the relay; other functions:
1, isolation (mainly refers to strong, weak electricity, or AC, DC);
2, protection; when the display (high-grade) displays the image and the audio power amplifier output is connected to the loudspeaker (loudspeaker), the relay is used.
3, step by step conversion; in electronic circuits, sometimes the control voltage or current is high or large, the primary relay can not be completed, then a number of relay will be used to transition.
If the power supply is directly supplied by the horn button, the button is easily damaged by the use of high frequency and high current. 2, the power loss of the line is long and the power loss is very uneconomical. 3, the power loss of the big horn is small, and the relay on the horn can increase the voltage. The normal trumpet passes through a lot of circuits, but after the relay is installed, it can be connected with the power supply directly to bypass the circuit to reach the maximum voltage to increase the loudspeaker's loudness.