Relay function: Controls the connection and disconnection of the circuit.

Relays play a crucial role in circuit design, mainly reflected in the following aspects:

1. Control and protection of circuits: Relays are electromechanical devices that use a small current to control a larger current, thereby controlling and protecting circuits. When the current in a circuit exceeds a specific value, the relay automatically cuts off the power to prevent overload or short circuit, thus protecting the circuit.

2. Isolation function: In some circuits, it is necessary to isolate different circuits to avoid interference and cross-influence. Relays can isolate different circuits through their own switching states, achieving the isolation function of circuits.

3. Signal conversion: In some circuits, it is necessary to convert input signals into specific output signals. Relays can convert input signals into specific output signals by controlling the action of the electromagnet, thus achieving the function of signal conversion.

4. Automated control: In systems requiring automated control, relays can serve as one of the control components, automatically controlling the operation of the circuit based on preset conditions and signals. For example, in an automatic door control system, relays can automatically control the opening and closing speed of the door based on signals such as the position and speed of the door.

Overall, relays play a very important role in circuit design, enabling functions such as circuit control, protection, isolation, signal conversion, and automated control.