Intro

Another alarm how to post for you!

Hardware

You will need the following:

A buzzer (with or without lead)
A MQ-135 sensor module
Arduino Uno R3
Connector leads
Arduino IDE

Overview Pic One

The VCC goes to the 5V pin on the Arduino, the gnd to gnd and the A0 pin to A0.
Positive pole pin on the buzzer goes to D9 (digital pin 9) on the Arduino and the negative to gnd.

Overview Pic Two

Sensor Connections Front

Sensor Connections Back

Code

Copy the code exactly as it appears in the pictures below.

Code Pic One

Code Pic Two

Code Pic Three

You can add change the code to implement digital input instead of analogue. You can also change the code to trigger an LED instead of a buzzer or both at the same time.

Usage

This alarm can detect a range of gases and can be used to monitor air quality. The analogue values are as follows: 100 -150 for normal air, 700 – 750 for alcohol in the air and 750+ for lighter gases. Use it to measure air quality in the room, check for Carbon dioxide and as a breath detector for alcohol.

The only drawbacks are burn in time – which is the time required for the sensor to reach maximum accuracy. The MQ-135 sensor needs 30 seconds to ‘burn in’ and the gas sensor stays hot while in operation, so watch your hands.

Survive and Thrive!

Minds: https://www.minds.com/AspiePrepper
Steemit: https://steemit.com/@aspieprepper
Youtube: https://www.youtube.com/channel/UC8WohhlmLNq2B5w3dV84Omw
Vidme: https://vid.me/AspiePrepper
Paypal: paypal.me/AspiePrepper