User Manual
81 
Lesson 33 Fire Alarm 
Introduction 
With the increasing use of fire and electricity in household, home fire accidents occur more 
and more frequently. Thus, fire alert plays a more important role in people's life. In this lesson, 
we will use a gas sensor, a flame sensor and a passive buzzer module to assemble a fire alarm. 
Components 
- 1 * SunFounder Uno board 
- 1 * USB data cable 
- 1 * MQ-2 Gas sensor module 
- 1 * Flame sensor module 
- 1 * Passive Buzzer module 
- Several jumper wires 
Experimental Principle 
Gas  sensors  can  detect  the  concentration of  smoke  generated  to  warn  of  possible  fires, 
when  flame  sensors  can  do  the  infrared  rays  emitted  by  fire.  Detecting  both  smoke  and 
flames, we can tell whether a fire's happened. At the same time, the buzzer will beep to warn. 
Experimental Procedures 
Step 1: Build the circuit 
Buzzer Connection: Connect pin S to D3 of Uno 
MQ-2 Gas Sensor Connection: Connect pin OUT to A1, VCC to 5V, and GND to GND 
Flame Sensor: Connect pin DO to D8, G to GND, and + to 5V 
Step 2: Program (Please refer to the example code in LEARN -> Get Tutorial on our website) 
Step 3: Compile 
Step 4: Upload the sketch to SunFounder Uno 
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