Temperature-Based DUAL SAFETY SYSTEM For Smart Homes

A temperature-based dual safety system addresses common household risks through intelligent control.

- RAKESH JAIN

Built on an Arduino Uno, it operates in two selectable modes via a slide switch. In one mode, the system closes the gas cylinder knob when milk temperature exceeds a preset threshold, preventing overflow. In the other, it switches off an electric heater rod when water temperature rises beyond a limit, preventing burns and electric shock. The threshold is set using a 4 × 4 keypad, while an LCD displays real-time temperature along with the set value.

Designed for everyday use, the device suits households with elderly users and children. It is cost-effective, easy to install, and uses components listed in the Bill of Materials table on next page.

Circuit and working

Fig. 1 shows the temperature-based dual safety system for smart homes. The system is built around an Arduino Uno (MOD1), a DS18B20 digital temperature sensor (S1), a 4 × 4 keypad (MOD2), a 16 × 2 LCD (LCD1), a servo motor (M1), a 5V relay (RL1), and supporting components.

The Arduino Uno acts as the main controller, processing sensor data and managing control operations. A relay controls the heater, while a servo motor operates the gas knob. Alternatively, an electronic gas valve or LPG solenoid valve may be used with minor code modifications.

A slide switch enables mode selection. For alerts, an LED and a buzzer provide visual and audio indication when the temperature exceeds the preset threshold. The relay is driven by a BC547 transistor with a flyback diode for protection, enabling safe control of an external AC load such as a heater.

During operation, the Arduino monitors the temperature, compares it with the set value, and triggers outputs such as the buzzer, LED, servo motor, and relay to ensure timely safety response and real-time monitoring.

The system operates in two modes selected using a slide switch: