Breath Analyzer

Breath analyzer


breathalyzer is a device for estimating blood alcohol content (BAC) from a breath sample. Breathalyzer is the brand name of a series of models made by one manufacturer of breath alcohol testing instruments and is a registered trademark for such instruments. In Canada, a preliminary non-evidentiary screening device can be approved by Parliament as an approved screening device, and an evidentiary breath instrument can be similarly designated as an approved instrument. The U.S. National Highway Traffic Safety Administration maintains a Conforming Products List of breath alcohol devices approved for evidentiary use, as well as for preliminary screening use.

Growing numbers of road users and the limited resources provided by current infrastructures lead to ever increasing number of accidents. The major accidents have a common reason behind them and that is the drunk driving. Due to the negligence of a single person, many lives get affected. This project aims at developing an ALCOHOL SENSOR BASED CAR CONTROL SYSTEM. This project has an alcohol sensor installed inside the car, whose output is a form of analog signal. This gas is consisting of alcohol particles and this analog signal is made to pass through an ADC and then forwarded to the microcontroller, which is a digital device. If the alcohol content of the driver is found to be more than a critical value, the microcontroller generates audio and visual alarm and besides it, microcontroller also disables the engine of the vehicle.


Project Description:

Our main motivation for creating the alcohol breath analyzer is to get alert from drunken people. In general, in intoxicated people are usually more care less and destructive than those not under the influence in our particular house, kitchen and library are 2 rooms that are vocationally left by an intoxicated. We decided to fabricate device that would allow sober housemates to use the facility while keeping the drunken ones out. Our breath analyzer initiates an alarm when a threshold concentration of alcohol is reached. The microcontroller does the above job it receives the signals from the sensors, and this signals operated under the control of software which is stored in ROM.



  1. A brief introduction to internal architecture of microcontroller.
  2. An over view of programming of microcontroller.
  3. An overview on C or assembly language.
  4. Alcohol sensor interfacing with microcontroller.


Block Diagram:

Breath analyzer
Breath analyzer

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