This reduces the sensor's overall resistance of the percentage alcohol.
When the alcohol tester is open, the heating coil sensors are inspired from May 7805 volts voltage regulator (IC5). Through self-test circuit cycle and the warm-up period. This circuit resets itself 0 alcohol reading and set ready for the light. When drunk blowing devices and sensor detects alcohol, its resistance decreases, this change the input voltage to the detector circuit. Detector circuit is composed of a quad op amp. Calibration of the detector circuit through a second resistor (R3 and R4), each part of the control voltage input divider (R21-R23). Each section is activated when the output to go low and the sample and hold circuit will catch the maximum input value and trigger appropriate leadership. Different colors represent different alcohol content of light-emitting diodes. If the detected alcohol content exceeds the legal limit (0.1%), and the other op amp will trigger the buzzer and LED corresponds to a "restricted" level of alcohol. This indicates that too many people drink and drive.