In this IoT project, I have shown how to make an IoT-based Home Automation project using ESP32 and the new Blynk IoT app to control an 8-channel relay module from the manual switch & smartphone.

During the article, I have shown all the steps to make this Blynk home automation system.

Tutorial Video on new Blynk ESP32 Smart Home

This Blynk ESP32 control smart relay has the following features:

  • Control home appliances with WiFi (Blynk IoT app).
  • Control home appliances with Blynk web dashboard.
  • Control home appliances with manual switches or push buttons.
  • Monitor real-time feedback in the Blynk IoT App.
  • Control appliances without WiFi from manual switches.

So, you can easily make this home automation project at home just by using an ESP32 and relay module. Or you can also use a custom-designed PCB for this project.

Required Components:

  • ESP32 DEVKIT V1 board
  • 8-channel SPDT 5V Relay Module
  • Push Buttons or Switches

You can make this project just by using ESP32 and 8-channel relay module. But if you use PCB then you need the following components.

Required Components for the PCB:

  • Relays 5v (SPDT) (8 no)
  • BC547 Transistors (8 no)
  • PC817 Optocuplors (8 no)
  • 510-ohm 0.25-watt Resistor (8 no) (R1 - R8)
  • 1k 0.25-watt Resistors (10 no) (R9 - R18)
  • 10k 0.25-watt Resistors (1 no)
  • LED 5-mm (10 no)
  • 1N4007 Diodes (8 no) (D1 - D8)
  • Push Buttons (9 no) or Switches
  • Terminal Connectors
  • Jumper
  • 5V DC supply

Required Software:

1. Blynk IoT app (Blynk 2.0)

2. Arduino IDE

Circuit Diagram of the ESP32 Home Automation Project:

This is the complete circuit diagram for this home automation project. I have explained the circuit in the tutorial video.

The circuit is very simple, I have used the GPIO pins D23, D22, D21, D19, D18, D5, D25 & D26 to control the 8 relays.

And the GPIO pins D13, D12, D14, D27, D33, D32, D15 & D4 are connected with Switches to control the 8 relays manually.

The Wi-Fi indicator is connected with the D2(GPIO-2) pin, connected with the blue LED mounted on the ESP32 board.

I have used the INPUT_PULLUP function in Arduino IDE instead of using the pull-up resistors.

I have used a 5V 5A DC power supply.

Control Relays With Blynk IoT App:

If the ESP32 is connected with WiFi, then you can control the home appliances from Blynk IoT App.

You also use multiple smartphones to control the appliances with Blynk IoT App. For that, you have to log in same Blynk account from all the smartphones.

In this way, all smartphones will be sink to the Blynk server. You can control, monitor the real-time status of the relays from anywhere in the world with the Blynk App.

Control Relays Manually With Buttons or Switches:

You can also control the relays from the switches or pushbuttons.

If the ESP32 is connected with Wi-Fi, you can monitor the real-time feedback in the Blynk IoT App.

And if the Wi-Fi is not connected, still you can control the relays from manual switches.

Please refer to the circuit diagram to connect the switches.

Designing the PCB for ESP32 IoT Projects:

To make the circuit compact and give a professional look, I have designed the PCB after testing all the features of the smart relay module on the breadboard.

You can download the PCB Gerber file of this home automation project from the following link:

Download the PCB Gerber File

Order the PCB from JLCPCB:

After downloading the Garber file you can easily order the PCB

1. Visit and Sign in / Sign up

2. Click on the QUOTE NOW button.

3. Click on the "Add gerber file" button. Then browse and select the Gerber file you have downloaded.

Uploading the Gerber File and Set the Parameters:

4. Set the required parameter like Quantity, PCB masking color, etc.

5. After selecting all the Parameters for PCB click on SAVE TO CART button.

Select Shipping Address and Payment Mode:

6. Type the...

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