Sensors some are three wires, some are four wires how to connect
Baidu Encyclopedia – Smoke Sensor
How to wire the smoke protection of Cebu Zhongmin Sanjie
1, “+” of the sensing is connected to the +12-volt power supply terminal of the host computer.
2, “_” connected to the ground terminal (GND) of the host computer.
3, sensor “K” to the host “smoke” terminal. Smoke protection: When smoke is generated, the smoke sensor sends this signal to the host computer to immediately realize smoke protection.
Detailed working principle of mq-2 smoke sensor? With the circuit diagram of this sensor.
MQ-2 4, 6 feet output with the smoke concentration of DC signals, was added to the comparator U1A 2 feet, Rp constitute the threshold voltage of the comparator. When the smoke concentration is higher output voltage is higher than the threshold voltage, the comparator output low level (0v), at this time the LED is bright alarm; when the concentration is reduced sensor output voltage is lower than the threshold voltage, the comparator flip output high level (Vcc), LED off. Adjustment of Rp, you can adjust the threshold voltage of the comparator, thus adjusting the sensitivity of the alarm output. R1 is serialized into the heating circuit of the sensor, which can protect the heating wire from the shock of cold power-up.