Description

Visible model: MQ-2.
Sensing principle: Tin-oxide semiconductor whose conductivity changes with gas exposure.
Visible connections: VCC, GND, DO (digital output) and AO (analog output).
Adjustment: Visible trimmer, typically used to set the digital detection threshold.
Construction: Mesh-covered metal sensor on a blue PCB with mounting holes.
Potential applications: Gas-detection experiments, smoke-response monitoring and alarm prototypes.