Arduino-Powered Alcohol Detection and Engine Turnoff System

This Prototype is designed to Turn off the automobile and Inhibit it from starting in case alcohol is detected in the breath of the driver. A MQ-3 sensor is used to detect the vapours of alcohol, It in turn produces a voltage proportional to the percentage of alcohol in the breath of the driver.This voltage is harnessed and amplified using an LM35 IC to produce an output voltage in a scale of 5V. A bias voltage of 5V is given to the IC.Thus(voltage/5)*100 gives the percentage of alcohol in the driver's breath.This voltage is read by the Arduino Micro Controller using the command "analog read (sensor pin)¿ If the percentage of alcohol in driver's breath is more than 50% then the 13th digital pin of the Arduino is turned to a logic HIGH which in further stages can be amplified to trigger the relay.