MQ-9 sensitive material used is a gas sensor in a clean air, the

lower the conductivity of tin dioxide (SnO2). Detection method

using low temperature cycling (1.5V heating) to detect carbon

monoxide, the conductivity of the sensor increases with the

increase of carbon monoxide in air gas concentration, stray adsorbed at

high temperatures (5.0V heating) detection of combustible gases methane,

propane

and clean low gas. Using a simple circuit to the change in conductivity, and

the concentration of the gas is converted to the corresponding output signal.

MQ-9 gas sensor high for carbon monoxide, methane, liquefied petroleum gas

sensitivity of this sensor can detect a variety of carbon monoxide and

combustible gases, is a low-cost sensors for a variety of applications

Module Features:
Using high-quality dual-panel design, with power indicator

and a TTL signal output instructions;
DO switching signal having (TTL) output and analog output AO;
TTL output valid signal is low. (When output low signal light,

can be directly connected microcontroller or relay modules)
Analog output voltage with the higher voltage, the higher

the concentration.
For carbon monoxide detector has good sensitivity.
There are four screw holes for easy positioning;
Product Dimensions: 32 (L) * 20 (W) * 22 (H)
Has a long life and reliable stability
Quick response and resume

Electrical properties:
Input voltage: DC5V Power consumption (current): 150mA
DO output: TTL digital 0 and 1 (0.1 and 5V)
AO output: about 0.1-0.3V (relatively clean), the highest

concentration of voltage 4V
Special note: After the sensor is energized, needs to warm

up around 20S, measured data becomes stable, the sensor

fever is a normal phenomenon, because the internal electric

wire, if not normal hot