Tuesday, April 29, 2025

Kitchen Security Alarm Using MQ2 Sensor

The most common cause of fire in a kitchen is gas leakage. This project will help you make an LPG leakage cum smoke detector kitchen security alarm using a gas sensor. The sensor will detect the intensity of LPG gas as well as smoke, if any. If the intensity of LPG gas or smoke exceeds a certain limit, an audible alarm will notify you to take care of the leakage as soon as possible.

efy tested

LPG/smoke detectors are amazing devices as they are small and low-cost, yet very useful. MQ2 is the most common metal oxide semiconductor (MOS) type of gas sensor. It is very sensitive to smoke and flammable gases like LPG, butane, propane, methane, alcohol, hydrogen, and carbon monoxide. When a gas comes in contact with the sensor, the circuit uses a simple voltage divider network to detect it.

Video Tutorial In English:

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Video Tutorial In Tamil:

You can also check the gas leakage detector that we build previously.

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Kitchen Security Alarm Circuit diagram
Fig. 1: Circuit diagram

The MQ2 sensor has two electrodes made of aluminum oxide (Al2O3) and a heating element made of tin dioxide (SnO2) that acts as the main sensing layer.

Kitchen Security Alarm Parts List
Semiconductors:
IC1-LM7805, 5V voltage regulator
IC2-LM358 op-amp
IC3-NE555 timer
T1, T2-2N2219 NPN transitor
BR1-1A bridge rectifier
LED1-5mm LED
D1-1N4007 rectifier diode
Resistors (all 1/4-watt, ±5% carbon):
R1, R2, R4, R5-1-kilo-ohm
R3, R7-680-ohm
R6-1-mega-ohm
Capacitors:
C1-1000μF, 35V electrolytic
C21000μF, 16V electrolytic
C3-10nF ceramic disk
Miscellaneous:
Exhaust fan-230V AC operated
RL1-5V, SPDT relay
CON1-CON3-2-pin connector
Sensor1-MQ2 gas sensor
X1-230V AC primary to 9V, 500mA secondary transformer

Kitchen Security Alarm – Circuit Connections

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4 COMMENTS

  1. Sir,
    Thank you very much for the simple, lifesaving, accident and disaster prevention circuit.
    Can we use single opamp instead of dual opamp?
    Shall we keep the unused opamp inputs floating?

    Register or Login to leave a comment.

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