IoT RELAY TO CONTROL APPLIANCES Through The Internet Using Smartphone

Electrical appliances such as lights, fans, air-conditioners, TVs, and water pumps are typically operated using manual switches.

- PRADIPTA GHOSH, CHALLA NAGA SAI RAVALI

This system enables these appliances to be controlled over the internet using a smartphone. It combines an ESP-01 WiFi module, the Switchsys MQTT broker (free public version), and the IoT MQTT panel app. The Switchsys MQTT broker implements the MQTT publish/subscribe communication model, enabling communication between the ESP-01 module and the user interface.

The IoT MQTT panel mobile application allows users to send on/off commands and monitor device status in real time from any location with internet access. Commands sent through the app are routed via the MQTT broker to the ESP-01, which processes the subscribed topic and drives the relay accordingly. This enables remote control of connected appliances from virtually anywhere. Fig. 1 shows the author’s prototype, while Table 1 lists the components required to build the system.

The system uses an ESP-01 WiFi module, a relay module, the Switchsys MQTT broker, and the IoT MQTT Panel app. It becomes operational when powered on. The ESP-01 connects to the WiFi network and communicates with the MQTT broker. The user sends on/off commands through the mobile app, which the ESP-01 receives via the broker. Based on the received command, the ESP-01 activates or deactivates the relay to switch the connected bulb on or off.

System design

In the IoT MQTT Panel app dashboard, there is a single switch to control the relay and an LED indicator to display the relay status.