Principle Introduction:
Winsen Electronics manufacture mini size alcohol sensors for gift-type breathalyzer use.
Sensitive material of MQ303B gas sensor is semiconductor material which is with lower conductivity in clean air. When the target alcohol gas exists, the sensor’s conductivity gets higher along with the gas concentration rising. Users can convert the change of conductivity to correspond output signal of gas concentration through a simple circuit.

Applications :
It has high sensitivity to alcohol and quick response and resume, widely used in portable alcohol gas detector.

Technical parameters :

Tips:For more parameter information, please refer to the latest manual provided by salesman.

Model			MQ303B
Sensor Type			Semiconductor
Standard Encapsulation			Metal
Target Gas			Alcohol gas
Detection range			20~ 500ppm alcohol
Standard Circuit Conditions	Loop Voltage	V H	0.9V±0.1V AC or DC
	Heater Voltage	V c	≤6V DC
	Load Resistance	R L	Adjustable
	Heater Resistance	RH	4.0Ω±0.5Ω（room temp.）
	Heater consumption	PH	≤140mW
Sensor character under standard test conditions	resistance of sensitive material	R0	1KΩ～400KΩ(in air)
	Sensitivity	S	R0(in air)/Rs(in 125ppm C2H5OH)≥3
	Concentration Slope	α	≤0.6(R300ppm/R50ppm C2H5OH)
Standard test conditions	Tem. Humidity		20℃±2℃ 55%±5%RH
	Standard test circuit		Vc:3.0V±0.1V DC VH: 0.9V±0.1V DC
	Preheat time		Over 48 hours

Reference Circuit :

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