In this IoT project, I have shown how to make an IoT-based Smart Home with Google Assistant & Alexa using NodeMCU ESP8266 to control 3 home appliances with voice commands.

If the internet is not available, then you can control the home appliances from manual switches. During the article, I have shown all the steps to make this smart home system.

This complete Home Automation system has the following features:

  • Control appliances with Google Assistant
  • Control appliances with Alexa
  • Control appliances manually with switches.
  • Monitor real-time feedback in the Google Home and Amazon Alexa App.
  • Control home appliances manually without internet.
  • All resources used for this project are FREE.

So, you can easily make this home automation project at home.

Required Components:

1. NodeMCU board

2. 4-channel SPDT 5V Relay Module

3. Manual Switches or Push Buttons

4. Alexa Echo Dot (Optional)

If you use the custom-designed PCB for this project, then please refer to the following required components list.

Required Components for the PCB:

1. Relays 5v (SPDT) (8 no)

2. BC547 Transistors (8 no)

3. PC817 Optocuplors (8 no)

4. 510-ohm 0.25-watt Resistor (8 no) (R1 - R8)

5. 1k 0.25-watt Resistors (10 no) (R9 - R18)

6. LED 5-mm (10 no)

7. 1N4007 Diodes (8 no) (D1 - D8)

8. Push Buttons (8 no)

9. Terminal Connectors

10. 5V DC supply

Required Software:

1. Arduino IDE

2. Google Home App

3. Amazon Alexa App

Circuit Diagram of the NodeMCU 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 D1, D2, D5 & D6 to control the 4 relays.

And the GPIO pins SD3, D3, D7 & RX connected with switches to control the 4 relays manually.

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

I have used a 5V mobile charger to supply the smart relay module.

Here, the D3 pin should not be connected with GND during the booting process of NodeMCU.

Control Relays With Google Assistant Using NodeMCU:

You can also control the home appliances from Amazon Alexa App if the NodeMCU is connected with the WiFi.

You can also ask Alexa to turn on and off the appliances.

You can also control the appliances from the manual switches and monitor the real-time feedback of the relays in the Amazon Alexa App from anywhere in the world.

You don't need any Echo DOT device for this home automation project.

Control Relays Manually With Switches:

If the WiFi is not available, you can control the relays from the manual switches.

The NodeMCU will check for the WiFi after every 5 seconds. When the WiFi is available, the NodeMCU will automatically connect with the WiFi.

Please refer to the circuit diagram to connect the manual switches.

Design the PCB for This Smart Home System:

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.

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

Order the PCB:

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 your 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 Shipping Address.

7. Select...

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