Note that the voltage of the workpiece in the circuit must not exceed the rated working voltage of the relay, otherwise the relay coil is easy to burn out.

Generally, there are many pairs of contacts, and the rated current of the contact capacity is about 5A to 10A.

The 5V relay is an automatic switch, which is often used in automatic control circuits, and uses a small current signal to control a large current. The input voltage range of the relay signal is 0 to 5V,

Use the electrical barrier of the multimeter to measure the resistance of the normally closed contact and the moving point, and the resistance should be 0;