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MQ-3:
Used in on-site testing of alcohol level of drinking car drivers, also used in other places for ethanol vapor detection applications.Tin oxide (SnO2) is a low electrical conductivity material in clean air, but with combustible gas, its conductivity increases. Using simple circuits, its changing in conductivity is changed into output signals. MQ-3 is sensitive to ethanol vapor.

Operating voltage Vc: less than 24V

Heater voltage Vh: 5.0V ±0.2V

Load resistance: adjustable

Heater resistance: 31 ohm ± 3 ohm

Heater power consumption PH: <=900mW

Dimensions：32(L)*20(W)*22(H)

Standard test conditions:
Temperature: 20 degree ± 2 degree
Humidity: 65% ± 5% RH
Standard test circuit: Vc: 5.0V ± 0.1V
Vh:5.0V±0.1V
Warm up time: more than 48 hours.

Connection:
VC：DC 5V @150mA
DO：TT Loutput 0 and 1（0.1 and 5V）
AO：Analog output 0.1-0.3V（no contamination），maximum contamination 4V
Note：Sensor need 20 sec, to stabilize after turning on.