automatic light control

[karmax]

hi ,
   i want to make automatic light control system .i want to make a system which itself know when i out from my room and its switch off all the lights of room.Any idea which sensor should we use. please help me .

[hopslink]

Have a look at passive infra-red (PIR) sensors. Those are the types typically used on burglar alarms and automatic lights to detect the presence of a moving heat source (human).

[cooldog]

just wire ur lights parallel to a motion sensor

[Pratheek]

You could use a sonar or a long range infrared sensor placed near the entrance of the room to detect anyone entering or leaving the room.

[karmax]

just wire ur lights parallel to a motion sensor

thanks for reply .but its not necessary that nothing is in motion inside room may be due to wind something vibrates.and when we are resting then we are also not in motion then also its switch off all lights.but i dont want.i want a system which can detect human presence

[karmax]

You could use a sonar or a long range infrared sensor placed near the entrance of the room to detect anyone entering or leaving the room.

thanks for reply .but how may i know tht  person entered or exit.

[Soeren]

Hi,

A dual receiver IR system (receivers mounted about 5cm to 10 cm apart) near the entrance/exit.
An up/down counter where one receiver controls the clock input and the other the direction. When the first person enters the room, the count goes from 0 to 1, next person 2 etc. (it count persons entering and exiting).
When the counter output is zero, the light is off, any other number will hold the light on.
In case of loose limbs resulting in miscounts, either use a reset button or count up/down with a hand to equalize.