[vick5821]

how about the accuracy ?

 

[davenn]

how about the accuracy ?

that will depend on the particular sensor
do some google searching on PIR sensors and get some data sheets

Dave

 

[vick5821]

In my project, where I have to demo, I will put a rubbish there and when start demo, I will burn it, then the PIR sensor will detect ?

 

[(*steve*)]

That won't require much accuracy

 

[vick5821]

If I put several LM 35 sensor in a small enclosed area, possible to make the LM 35 sense the raise in temperature by the heat of the combustion ?

 

[(*steve*)]

Only if you light a fire under them.

(That means NO)

edit: actually, it means yes if you literally place them in an enclosure that is heated by the fire. But unless they are actually heated by the fire, they won't detect anything.

On the other hand, something that can detect the black body radiation from the fire can do so at a distance.