Circuit Documentation

Summary

This circuit integrates various sensors and components with an Arduino UNO microcontroller to monitor environmental conditions and control a fan. The sensors include a DHT11 humidity and temperature sensor, MQ135 and MQ-4 gas sensors, and an LED indicator. The Arduino UNO processes the sensor data and controls the fan based on the readings.

Component List

DHT11 Humidity and Temperature Sensor

• Description: Measures humidity and temperature.
• Pins: VDD, DATA, NULL, GND

120 Fan 12V

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

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

MQ135 Gas Sensor

• Description: Detects various gases including CO2.
• Pins: VCC, GND, A0, D0

MQ-4 Gas Sensor

• Description: Detects methane (CH4) gas.
• Pins: A0, D0, GND, VCC

LED: Two Pin (Red)

• Description: A red LED indicator.
• Pins: Cathode, Anode

Resistor

• Description: A 200 Ohm resistor.
• Pins: Pin1, Pin2
• Properties: Resistance: 200 Ohms

12V Battery

• Description: A 12V power source.
• Pins: VCC, GND

Wiring Details

DHT11 Humidity and Temperature Sensor

• VDD connected to 5V on Arduino UNO
• DATA connected to D2 on Arduino UNO
• GND connected to GND on Arduino UNO

120 Fan 12V

• 12V+ connected to VCC on 12V Battery
• GND connected to GND on 12V Battery

Arduino UNO

• 5V connected to VCC on DHT11, MQ135, and MQ-4
• GND connected to GND on DHT11, MQ135, MQ-4, and LED cathode
• A0 connected to A0 on MQ135
• A1 connected to A0 on MQ-4
• D13 connected to Pin2 on Resistor
• D4 connected to D0 on MQ-4
• D3 connected to D0 on MQ135
• D2 connected to DATA on DHT11

MQ135 Gas Sensor

• VCC connected to 5V on Arduino UNO
• GND connected to GND on Arduino UNO
• A0 connected to A0 on Arduino UNO
• D0 connected to D3 on Arduino UNO

MQ-4 Gas Sensor

• VCC connected to 5V on Arduino UNO
• GND connected to GND on Arduino UNO
• A0 connected to A1 on Arduino UNO
• D0 connected to D4 on Arduino UNO

LED: Two Pin (Red)

• Anode connected to Pin1 on Resistor
• Cathode connected to GND on Arduino UNO

Resistor

• Pin1 connected to Anode on LED
• Pin2 connected to D13 on Arduino UNO

12V Battery

• VCC connected to 12V+ on 120 Fan 12V
• GND connected to GND on 120 Fan 12V

Documented Code

Arduino UNO Code (sketch.ino)

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

}

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

}

Additional Documentation (documentation.txt)

This documentation provides a comprehensive overview of the circuit, including a detailed component list, wiring details, and the code used for the Arduino UNO microcontroller.