Alcohol used to monitor gas concentration gas sensor circuit diagram

  
Ceramic gas sensors can also be used to analyze the content of alcohol vapor. With the corresponding sensor circuit can be detected with a blood alcohol content. Its working pr
Alcohol used to monitor gas concentration gas sensor circuit diagram - schematic

inciple is very simple, if the blood alcohol content contained in a certain proportion, then it will certainly diverge into the air, the higher the blood alcohol concentration in the air diverging ratio is greater. If the air is blowing sensor contains a concentration of alcohol, the resistance of the sensor will react with a corresponding change in the alcohol concentration, the change can be a suitable measuring circuit identification. Such a circuit is shown in Figure 8-24. TGS 822 gas sensor used is manufactured by Figaro. Circuit from the regulated DC power supply + 5V supply. The sensor output voltage of the inverter load resistor load to the input of three operational amplifiers, comparators into three interconnected. In fact, the resistors R1 and R2 are the reference voltage generator. Upper limit reference voltage set by the variable resistor RP1, RP2 is set by the lower limit. After power on, and press the reset button and the trigger to enter the logic O state. In this case, the light emitting diode LED1 ~ LED3 does not emit light. When alcohol vapor acting on the sensor, the voltage drop across the load resistor begins to change (gradually increased). The results of these discrete comparators work order results in a corresponding trigger open, so they are in contact with the LED lights. If the alcohol vapor sensor to stop action, then the voltage on the load resistance will decline slowly. After pressing the reset button, back to the initial state. In order to compensate for the effects of temperature and humidity on the sensor characteristics, and in order to obtain greater accuracy, we recommend using a thermistor and (or) humidity sensor circuit to compensate.




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