help: how smoke and flam detector works???

[eng_ahmed22]

Hi all

i want to design fire alarm system using AT89cxx,
but i dont know how smoke detector works, or what is its behavior when it detect smoke, to enable me to know that there r fire at any place.
what its out voltage in normal state and in fire state??
how they are connected???

plz help

ahmed

 

[EcraZ]

It basically has two sensors which detects heat and light seperately and internally anded so that the sensor gives an output only when there is heat and light both present as in the case of a flame

 

[tbksandeep]

The theory behind the smoke or gas detectors is interferometry.Try searching for Mach-Zhender interferometry.Try searching in google for interferometry methods.This would quite help u to get with the detectors

Added after 14 minutes:

i actually forgot to mention about the gas pressure sensors.please refer to that and also refer to the mach-zhender interferometry

 

[House_Cat]

How smoke sensors work is described at:
**broken link removed**

How flame detectors work is described at:
**broken link removed**

You would need the data sheet for the sensor you are planning to use in order to determine the exact parameters for your particular circuit. There are links to specific manufacturers on each of the above reference pages.