Introduction: Arduino Relay Module

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In this article, we outlined how to control high voltage devices using Arduino Relay.



Arduino Uno

Relay Module

Plug and Socket

Jumper Wires


Arduino IDE

Step 1: About This Project

We can easily control high voltage electronic devices using relays. A Relay is actually a switch that is electrically conducted by an electromagnet.

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The electromagnet is initiated with a low voltage, for example, 5 volts from a microcontroller and it extracts a contact to make or break a high voltage circuit. It can manage up to 230V devices. Inside of it, there are electromagnets with a contact that closes the circuit when you apply voltage to it.

How to use relay module with the High Voltage Devices : Let’s take a look at the circuit diagram. As previously defined we will use a 5V Adapter as a separate power supply for the electromagnet connected to the JDVcc and the Ground pin.

The Arduino’s 5V pin will be attached to the Vcc pin of the module and the pin number 7 to the In1 input pin for managing the relay. Now for the HIGH Voltage part, we need a power plug, a socket and a cable with two wires. One of the two wires will be cut and attached to the common and the normally open pin of the module output connector.

So with this configuration when we will initiate the relay we will get the high voltage circuit closed and working. Also connected the ends of the cable to the plug and the socket.

Example of a demonstration of Lamp using the relay module as shown in the image.

Step 2: Run a Program

int in1 = 7;

void setup()


pinMode(in1, OUTPUT);

digitalWrite(in1, HIGH);


void loop()


digitalWrite(in1, LOW);


digitalWrite(in1, HIGH);