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Make a Fire Alarm Circuit using MQ-2 Gas Sensor - KT857

Make a Fire Alarm Circuit using MQ-2 Gas Sensor - KT857

SKU:KT857

1000 in stock

Regular price Rs. 500.00
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KIT INCLUDES:


HARDWARE REQUIRED

SPECIFICATIONS

MQ-2 gas sensor module

Gas Sensor (MQ2) module is useful for gas leakage detection (home and industry). It is suitable for detecting H2, LPG, CH4, CO, Alcohol, Smoke or Propane. Due to its high sensitivity and fast response time, measurements can be taken as soon as possible.

  • Detection range: 300 to 10000ppmm
  • The characteristics gas: 1000ppmm, isobutene
  • Sensitivity: R in air / Rin, typical gas ≥ 5
  • Sensing Resistance: 1KΩ 50ppm toluene to 20KΩ in.
  • Response time: ≤ 10s
  • Recovery time: ≤ 30s
  • Heat resistance: 31Ω ± 3Ω
  • Heating current: ≤ 180mA
  • Heating voltage: 5.0V ± 0.2V
  • Heating power: ≤ 900mW
  • Measuring voltage: ≤ 24V
  • Working conditions of ambient temperature: -20 ~ +55
  • Humidity: ≤ 95% RH
  • Environmental oxygen content: 21%
  • Storage conditions Temperature: -20 ° C to +70 ° C
  • Humidity: ≤ 70% RHSupply Voltage:5V
  • Sensitive to H2, LPG, CH4, CO, Alcohol, Smoke or Propane
  • Analog and Digital Output
  • Digital Out is high or Low based on an adjustable preset threshold.

PIN DESCRIPTION

MQ-2 Gas Sensor module

LM358 IC

The voltage regulator 7805 IC

Led

Capacitor

Diode

CIRCUIT DESCRIPTION

  • LM 358 IC and MQ - 2 Sensor connected to the Breadboard.
  • MQ - 2 Sensor vcc Pin connected to the positive supply and GND Pin connected to the GND, output Pin connected to the LM 358 IC Pin No. 3.
  • LM 358 IC Pin No. 4 is GND and Pin No. 8 connected to the positive supply.
  • LM 358 IC Pin No. 1 to connected 570ohm(470+100) Resistor and resistor 2nd leg to connected led positive leg, led negative leg is GND.
  • LM 358 IC Pin No. 1 to connected Buzzer positive leg and Buzzer negative leg is GND.
  • 10K Pot 1st leg is GND and 2nd leg connected to the positive supply, Middle leg connected to the LM 358 Ic Pin No. 2.
  • Voltage Regulator IC 7805 1st Pin to connected positive supply and 2nd pin is GND, 3rd Pin to connected 1000uF capacitor positive leg and negative leg is GND.
  • Both Diode 1N4007 positive leg connected to the positive supply and negative leg connected to the 7805 IC pin no 3rd.
  • Positive supply to connected 570ohm(470+100) Resistor and resistor 2nd leg to connected Led positive leg, led negative leg is GND.
  • Breadboard connection positive to positive and negative to negative.

WORKING

The op-amp LM358 is designed in a comparator mode which compares the signal received from the sensor to a threshold voltage (reference voltage). A potentiometer of 10kΩ is connected at pin no. 2.It is set at 2V (reference voltage). The voltage 2V is equal to the output voltage of the gas sensor in normal air conditions i.e. in absence of gas or higher heating temp. LM358 compares two input i.e. preset voltage i/p at inverting end with gas sensor o/p voltage at the non-inverting end. In absence of gas/Higher heating the output voltage of the gas sensor is 2V thus the overall output voltage of op-amp will be 0V. In the presence of combustible gases, input voltage reduces and output voltage of gas sensor increases thus creating the difference between two input voltages of op-amp. Thus output voltage of LM358 lead to triggering of buzzer and thus alarm sound generates and LED glows showing the presence of combustible gas / heat.