How to Use Relay with Arduino?

1.Introduction
 

In daily life, we generally use AC to drive electrical equipment, and sometimes we use switches to control electrical appliances. If the switch is directly connected to the AC circuit, once electricity leakage occurs, people are in danger. From a safety point of view, we specially designed this relay module with NO (normally open) and NC (normally closed) terminals. In this lesson we will learn a special and easy-to-use switch, which is the relay module.

2.Components Required
 

3.Component Knowledge
 

Relay:

It is an “automatic switch” that uses a small current to control the operation of a large current.

• Input voltage：5V

• Rated load：5A 250VAC (NO/NC) 5A 24VDC (NO/NC)

The rated load means that a 5V Arduino can be used to control a device with a 24V DC voltage or a 250V AC voltage.

Schematic diagram of the Relay:

4.Schematic Diagram and Wiring Diagram
 

5.Code
 

/*
Relay
http//www.keyestudio.com
*/
int Relay = 3; // defines digital 3
void setup()
{
pinMode(Relay, OUTPUT); // sets "Relay" to "output"
}
void loop()
{
digitalWrite(Relay, HIGH); // turns on the relay
delay(2000); //delays 2 seconds
digitalWrite(Relay, LOW); // turns off the relay
delay(2000); // delays 2 seconds
}

6.Result
 

Upload the code to the mainboard successfully, wire up and power on, the relay will be turned on (ON end is connected) for 2 seconds, and stop (NC end is connected) for 2 seconds, circularly.