In this tutorial, we are making a project on a Smoke detector alarm. We all know that there’s always a danger of things getting caught in a fire which can cause damage on many levels. There is always a smoke detector present inside every building or house, they are very useful as they provide an early indication of fire and make it possible to take immediate action to prevent subsequent damage.
This circuit is simple and can be easily made, it has a smoke sensor that detects any smoke around it and then activates a loud alarm to provide an indication. The smoke sensor used in this circuit is the MQ2 smoke/gas sensor.
Hardware Components
The following components are required to make a Smoke Detector Alarm Circuit
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | Input Supply DC | 5-12V | 1 |
| 2. | Smoke Sensor | MQ2 | 1 |
| 3. | IC | LM358, UM66 | 1, 1 |
| 4. | Transistor | 2N4401, S8550 | 1, 1 |
| 5. | Resistor | 12KΩ, 1KΩ, 10K Var | 1, 3, 1 |
| 6. | Electrolytic Capacitor | 0.1µF | 1 |
| 7. | Speaker | 8Ω | 1 |
| 8. | Zener didoe | 3V | 1 |
LM358 Pinout
The following components are required to make LM358
UM66 Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of UM66
Smoke Detector Alarm Circuit
Working Explanation
The operating voltage of this circuit is 5 to 12 volts DC and it is built around an LM358 op-amp IC. This IC is working here In a comparator mode. When the smoke is detected by the MQ2 smoke detector it will send a signal to the IC to activate it. This IC will activate the transistor. This transistor is acting as a switch for the alarm circuit that is built around a CMOS melody generator IC UM66. When it activates it will generate a melody signal that is amplified by a transistor before going to the speaker. An 8 ohms speaker is used to provide the alarm signal, to make this alarm loud we have used an amplifier.
Applications and Uses
It can be used to detect any type of smoke and other inflammable gases like Methane, Alcohol Butane, Propane, etc.
