How to use commercial smoke detector within our circuits

[Mrunal Ahirrao]

Hello,

I am struggling to know how to interface the commercial smoke detectors used in fire alarm.I am not able to understand the logic of interfacing these detectors. I have one from system sensor model no-2351E named SMOKE DETECTOR-PHOTO. I am not able to find datasheet of this model but found some wiring diagram on google. But I am not able to understand those wiring diagrams do they work on digital NO/NC or analog? Actually I am building fire alarm system for home but got stuck on how to interface these sensors with microcontroller... Any help would be appreciated.

 

[FvM]

The usage is described in datsheets e.g.

One or multiple detectors are connected in parallel to a party line, supplied by 12 to 24 V DC through a 470 resistor. If a detector trips, it shorts the line (latched), causing a high voltage drop at the resistor. Opening the loop resets the latch.

 

[Mrunal Ahirrao]

so the voltage drop has to be measured using microcontroller ADC?

 

[FvM]

It's a pure digital information, voltage drop above a certain level = detector tripped.