Circuit Documentation

Summary

This circuit involves an Arduino UNO microcontroller interfacing with an MQ-2 gas sensor, a DHT 11 temperature and humidity sensor, a 5V relay, and a 12V fan powered by a 12V battery. The Arduino UNO reads data from the sensors and controls the relay, which in turn controls the fan.

Component List

Arduino UNO

• Description: A microcontroller board based on the ATmega328P.
• Pins: UNUSED, IOREF, Reset, 3.3V, 5V, GND, Vin, A0, A1, A2, A3, A4, A5, SCL, SDA, AREF, D13, D12, D11, D10, D9, D8, D7, D6, D5, D4, D3, D2, D1, D0

MQ-2

• Description: A gas sensor that detects LPG, i-butane, propane, methane, alcohol, hydrogen, and smoke.
• Pins: GND, VCC, ANALOG, Digital

DHT 11

• Description: A temperature and humidity sensor.
• Pins: VCC, GND, DATA

120 Fan 12V

• Description: A 12V fan.
• Pins: 12V+, GND

5V Relay

• Description: A relay module that can be controlled by a 5V signal.
• Pins: Normally Open, Common terminal, Normally Closed, In, GND, VCC

12V Battery

• Description: A 12V battery for powering the fan.
• Pins: VCC, GND

Wiring Details

Arduino UNO

• 5V connected to VCC of MQ-2, DHT 11, and 5V relay
• GND connected to GND of MQ-2, DHT 11, and 5V relay
• A0 connected to ANALOG of MQ-2
• D3 connected to In of 5V relay
• D2 connected to DATA of DHT 11

MQ-2

• VCC connected to 5V of Arduino UNO
• GND connected to GND of Arduino UNO
• ANALOG connected to A0 of Arduino UNO

DHT 11

• VCC connected to 5V of Arduino UNO
• GND connected to GND of Arduino UNO
• DATA connected to D2 of Arduino UNO

120 Fan 12V

• 12V+ connected to VCC of 12V Battery
• GND connected to Normally Open of 5V relay

5V Relay

• VCC connected to 5V of Arduino UNO
• GND connected to GND of Arduino UNO
• In connected to D3 of Arduino UNO
• Normally Open connected to GND of 120 Fan 12V
• Common terminal connected to GND of 12V Battery

12V Battery

• VCC connected to 12V+ of 120 Fan 12V
• GND connected to Common terminal of 5V relay

Documented Code

sketch.ino

void setup() {
  // put your setup code here, to run once:

}

void loop() {
  // put your main code here, to run repeatedly:

}

documentation.txt