Description
ESP8266 Wi-Fi-Based 4-Channel Relay PCB Board for Home Automation Project. This Board Included the Esp8266 module, 4-Channel 5V Relays, 817 Opto-couplers, DC Jack and other components with through-hole LED for indication purposes. This 5V 4-Channel relay board is controlled directly by esp8266 over Wi-Fi. 
This ESP8266-based Relay Module is suitable for wirelessly controlling appliances via WiFi. It is a four-channel relay module that can control up to 240V AC and 28V DC with a load capacity of 7A in 240VAC and 10A in 28VDC. ESP8266 will manage everything, once programmed and powered making it suitable for internet of things (IoT) projects. 
ESP8266 is a serial Port WIFI Wireless Transceiver Module for Arduino which is a small WIFI transceiver that is the perfect solution for home Automation and IoT applications. It can be the replacement of your NRF24L01, it can talk to your WIFI router directly through the UART MCUs.
ESP8266 Pin Configuration
| Pin 1 | Reset Pin of the module |
| Pin 2 | Analog Input Pin for 10-bit ADC |
| Pin 3 | Module Enable Pin |
| Pin 4 | General Purpose Input Output Pin 16 |
| Pin 5 | General Purpose Input Output Pin 14 |
| Pin 6 | General Purpose Input Output Pin 12 |
| Pin 7 | General Purpose Input Output Pin 13 |
| Pin 8 | +3.3V Power Input |
| Pin 9 | Chip selection Pin of SPI interface |
| Pin 10 | MISO Pin of SPI interface |
| Pin 11 | General Purpose Input Output Pin 9 |
| Pin 12 | General Purpose Input Output Pin 10 |
| Pin 13 | MOSI Pin of SPI interface |
| Pin 14 | Clock Pin of SPI interface |
| Pin 15 | Ground Pin |
| Pin 16 | General Purpose Input Output Pin 15 |
| Pin 17 | General Purpose Input Output Pin 2 |
| Pin 18 | General Purpose Input Output Pin 0 |
|  Pin 19 | General Purpose Input Output Pin 4 |
| Pin 20 | General Purpose Input Output Pin 5 |
| Pin 21 | UART0 RXD Pin |
| Pin 22 | UART0 TXD Pin |
Specification
| Model | Wifi-Based 4-Channel Relay |
| No. of Switching Channel | 04 |
| Technology | Wifi Based |
| Compatible Board | ESP8266 Wifi Module |
| Network Protocols | IPv4, TCP/UDP/HTTP/FTP |
| Frequency Range | 2.4 GHz-2.5 GHz( 2400 M-2483) |
| Operating Voltage | 5V DC |
| Input | 230V AC 50Hz |
| Maximum AC load current | 7A @ 250/ 10A @ 120V AC |
| Maximum DC load current | 10A @ 28V DC |
| Wireless Standards | 802.11 b/g/n |
| Board Size (L*W*D) | 79mm*192mm*17mm |
| Origin | Make in India |
| Country of Origin | China |