Fire alarm circuits in commercial buildings like offices, movie theaters, and malls have become a necessity. There are many typical and complex fire alarm circuits available in the form of standalone devices. But this tutorial will explain to you a simple fire alarm circuit using LM358. The fire alarm circuit using LM358 is a simple project which detects the fire and triggers the siren sound or a buzzer.
In the present era, almost every industry, company, or organization is highly concerned with the security of their data and work. So the Fire alarm circuit plays a vital role in their security systems as it helps detect and prevent damage.
Hardware Components
The following components are required to make a Fire Alarm Circuit
| S. NO | Components | Value | Qty |
|---|---|---|---|
| 1. | Breadboard | – | 1 |
| 2. | Battery | 9v | 1 |
| 3. | Connecting Wires | – | 1 |
| 4. | Opamp IC | LM358 | 1 |
| 5. | Thermistor | 10k | 1 |
| 6. | POT | 10k | 1 |
| 7. | Buzzer | – | 1 |
| 8. | Resistor | 10k | 1 |
LM358 Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of LM358
Fire Alarm Circuit
Working Explanation
The working and design of a Fire alarm circuit using LM358 is quite simple. LM358 is a dual-operational amplifier. In this project, this IC operates in Comparator mode. The input signals are applied to the inverting terminal whereas non-inverting terminals are compared and the output is produced. The circuit uses the NTC thermistor whose resistance decreases whenever the temperature increases. In the case of a fire, the temperature rises which reduces the resistance of a thermistor. This increases the output of a voltage divider that is connected to the non-inverting terminal of the op-amp. As a result, the output of the op-amp becomes high and turns the buzzer ON.
Application
- Offices
- Movie Theaters
- Shopping Malls
This really answered my problem, thank you!