Relay Module | How to make a Relay module with Optocoupler

Relay modules play a  important role in controlling high-voltage devices using low-voltage microcontrollers or digital circuits. They act as a bridge between the low-power electronics and the high-power  appliances.

 

In this blog post, we'll explore How to make a Relay module with Optocoupler.

 

What is Relay Module ?

Relay is a electro-mechanical switch that allows to control a high voltages and currents loads like AC lights, motors etc. using a low-current input signal that came from Microcontrollers or Sensors.It consists of an electromagnet, a set of contacts and a spring.

Relay Module Overview

A Relay module includes a Coil, Normally open(NO) Terminal, Normally closed(NC) Terminal and Common(COM) Terminals.

➨Coil: When electrical current is passed through, it generates a magnetic field.
➨Common(COM):Connected to Load terminal.
➨Normally Closed(NC):connected to the load terminal before the relay turned on.
➨Normally Open(NO): connected to the load terminal after the relay turned on.

How Relay module works

When an electrical current flow through the coil then coil is energized and generates a magnetic field. There have a movable component that is attracted by the magnetic field and it make a contacts between Normally closed(NC) and Common(COM)) Terminals of the Relay.

When electrical current turned off then disappears the magnetic field and the movable component returns to its original position, breaking the switch connection between Normally open(NO) and Common(COM)) terminal.

PC817-Optocoupler Overview

PC817 is a Optocoupler also known as an opto-isolator that includes a IR diode on the input side and a phototransistor(photodetector) on the output side.

Optocoupler use for transmit electrical signal between two isolated circuits using light waves.

Components Required for making a Relay Module

⇨5V Relay--1 pcs
⇨817c Optocoupler-1 pcs
⇨Green LED-1 pcs
⇨IN4007 Diode-1 pcs
⇨BC547 Transistor-1 pcs
⇨Screw Terminal -1 pcs
⇨Male Pin Header
⇨1 KΩ Resistors-1 pcs
⇨330Ω Resistors-1 pcs
⇨Power Supply-+5 Volt DC.

Complete Circuit Diagram Of Relay Module

 

Click on the Download buttons to download the Circuit Diagram of Relay Module

 

Step By Step Video Tutorial Of How to make a Relay module with Optocoupler

 

 

Frequently Asked Questions 

What is Relay Module?

Relay is a electro-mechanical switch ,consists of an electromagnet, a set of contacts and a spring.Relay allows to control a high voltages and currents loads like AC lights, motors etc. using a low-current input signal that came from Microcontrollers or Sensors.

Why diode is used in the relay circuit?

When the relay coil is de-energized, it can generate a reverse voltage spike (back electromotive force) that may damage the circuit. A flyback diode, connected in parallel with the relay coil, provides a path for this voltage to circulate harmlessly and it protect other components.

What is Optocoupler?

Optocoupler also known as an opto-isolator that includes a IR diode on the input side and a phototransistor(photodetector) on the output side.Optocoupler use for transmit electrical signal between two isolated circuits using light waves.

Why optocoupler is used in a relay module circuit?

An optocoupler provides electrical isolation between the low-voltage control circuit and the high-voltage load .This isolation helps to protect the low-voltage components from potential damage due to voltage spikes or fluctuations in the high-voltage circuit.

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