High sensitive alcohol sensor and gas leak with alert buzzer
ABSTRACT:
Sensitive material of MQ-6 gas sensor is SnO2, which with lower conductivity
in clean air. When the target combustible gas exist, the sensor’s conductivity is
higher along with the gas concentration rising. MQ-6 gas sensor has high sensitivity
to Propane, Butane and LPG, also response to Natural gas. The sensor could be used
to detect different combustible gas, especially Methane; it is with low cost and
suitable for different application.
LPG Gas Sensor (MQ6), ideal sensor for detect the presence of a dangerous LPG
leak in your Home, car or in a service station, storage tank environment. This unit can be
easily incorporate into an alarm unit, to sound an alarm or give a visual indication of the
Combustible Gas / LPG concentration. The sensor has excellent sensitivity combined
with a quick response time. The sensor can also sense iso-butane, propane, LNG and
cigarette smoke.
This LPG Gas Sensor can be used to make wireless Gas leak detector in home
security system This project is High Sensitivity to LPG, iso-butane, propane. This also
can sense to alcohol and smoke, but with poor sensitivity. This project is designed to
detect the LPG from 100parts per million (PPM) to 10,000 PPM. Whenever LPG is
detected, the sensor produces the output voltage, which is depended on the amount of gas
leakage. This voltage drives the transistor into saturation region. A buzzer is connected to
produce audible alert signal.
This project uses regulated 5V, 750mA power supply for charging the battery.
7805 three terminal voltage regulator is used for voltage regulation. Bridge type full wave
rectifier is used to rectify the ac output of secondary of 230/18V step down transformer.
For Details Contact: A.VINAY-9030333433, 0877-2261612
BLOCK DIAGRAM:
LPG Sensor
Sensitivity Control
Circuit
Transformer
transf
Driver Circuit
Buzzer
WORKING:
The circuit consists of a sensor which senses gas. The sensor is connected to the IC
LM358 as a comparator. The comparator output is fed to an LED. For generating the sound
signals the comparator output is fed to the second comparator. Here the second comparator is fed
with a reference voltage which is fed from a7805 voltage regulator. The output is fed to the
buzzer.
Connect the sensor to the circuit. Initially when the sensor MQ-6 detects the gas it
generates a voltage which is send to pin number 3 of LM358 .Here the first op-amp in LM358 is
used .Reference voltage of 5v is applied to pin number 2 of LM358 . The input of the first opamp is compared and output is taken from pin number 1.This will glow the led connected to pin
number 1. In order to generate a sound signal, additional circuitry is attached to the present
circuit .For this pin number 5 is shorted with pin number 1. Again a reference voltage of 5v from
a 7805 voltage regulator, fed with 9v, is fed to pin number 6 of LM358 .During this time the
second op-amp of LM358 functions. Hence inputs at pin number 6 and 5 are compared. When
the output at pin number 5 goes above the reference input there is a 0 to 1 transition in the output
pin number 7 .This will glow the led connected to pin number 7. Correspondingly it switches on
the transistor Q1. When Q1 reaches saturation it activates the buzzer and it generates the desired
sound.
For Details Contact: A.VINAY-9030333433, 0877-2261612
POWER SUPPLY:
The input to the circuit is applied from the regulated power supply. The a.c.
input i.e., 230V from the mains supply is step down by the transformer to 12V and is fed
to a rectifier. The output obtained from the rectifier is a pulsating d.c voltage. So in order
to get a pure d.c voltage, the output voltage from the rectifier is fed to a filter to remove
any a.c components present even after rectification. Now, this voltage is given to a
voltage regulator to obtain a pure constant dc voltage.
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Step Down T/F
Bridge Rectifier
Filter
Voltage
Regulator
For Details Contact: A.VINAY-9030333433, 0877-2261612
ADVANTAGES:

Good sensitivity to Combustible gas in wide range

High sensitivity to Propane, Butane and LPG
 Long life and low cost

Simple drive circuit
APLICATIONS:
 It has wide application in various security system
 It is used in Domestic gas leakage detector
 Industrial Combustible gas detector
 Portable gas detector
For Details Contact: A.VINAY-9030333433, 0877-2261612