Overheat Warning System Experimental Demonstration.

This video shows the experimental setup and testing of my temperature warning circuit using an LM35 temperature sensor and an LM358 operational amplifier used as a comparator. The circuit is designed to turn ON an LED when the sensed temperature goes above the reference threshold voltage. In the experiment, the LM35 sensor measures temperature and gives an output voltage proportional to temperature. The LM358 compares the LM35 output voltage with the reference voltage created by a resistor divider. When the LM35 output voltage is lower than the threshold voltage, the comparator output remains LOW and the LED stays OFF. When hot air is applied to the sensor, the LM35 output voltage increases. Once it becomes higher than the threshold voltage, the LM358 output goes HIGH and the LED turns ON. During testing, the supply voltage, threshold voltage, LM35 output voltage, and comparator output were checked using a multimeter. The resistor divider was adjusted to set a proper threshold voltage so that the LED would not turn ON immediately at room temperature. After replacing the divider resistors with 10 kΩ and 1 kΩ, the circuit worked correctly. This experiment confirms that the circuit can detect an increase in temperature and provide a visual warning using an LED. In a real application, the output can be connected to a buzzer or cooling fan for overheating protection.