In this IoT project, I have shown how to make an IoT-based ESP32 Alexa Smart Home System to control 8 home appliances from the manual switch & Amazon Alexa App. 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 home automation system.

This ESP32 control smart relay has the following features:

  • 1. Control home appliances with voice commands using Alexa
  • 2. Control home appliances with manual switches.
  • 3. Monitor real-time feedback in the Alexa App.
  • 4. Control home appliances manually without internet.
  • 5. Just need Echo Dot. No third-party app required.

Required Components:

1. ESP32 DEVKIT V1 board

2. 8-channel SPDT 5V Relay Module

3. Alexa Echo Dot

4. Manual Switches

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. Amazon Alexa App

Circuit Diagram of the ESP32 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 connected with switches to control the 8 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.

Testing the Circuit Before Designing the PCB:

If the ESP32 module is connected with the WiFi, then you can control the home appliances from Amazon Alexa App and also from the manual switches.

You can control, monitor the real-time status of the relays in the Alexa App. The ESP32, Amazon Echo Dot should be connected to the same WiFi network.

Control Relays Manually With Switches:

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

The ESP32 will check for the WiFi after every 3 seconds. When the WiFi is available, the ESP32 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 the Shipping Method suitable for you.

8. Submit the order and proceed with the payment.

You can also track your order from the

My PCBs took 2 days to get manufactured and arrived within a week using the DHL delivery option.

PCBs were well packed and the quality was really good at this affordable price.

Solder All the Components on PCB:

After that, I have soldered all the components as per the circuit diagram.

Then connect the ESP32 board with PCB.

Program ESP32...

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