Abstract: This system provides a unique method to curb drunken people. The system has an alcohol sensor embedded on the steering of the car. Whenever the driver starts ignition, the sensor measures the content of the alcohol in his breath and automatically switches off the car if he is drunken. In this system the sensor delivers a current with a linear relationship to the alcohol molecules from zero to very high concentration. The output of the sensor is fed to the pic microcontroller for comparison. If the measured value reaches the threshold, relay cut off automatically and the buzzer produces sound.
Keywords: PIC16F877A, CMOS, MQ-3 gas sensor.