A bit delayed post. :D Apologies...
Recently I received a few boards and accessories which was ordered previously through Ali Express. Don't mind if I say that AliExpress is one of the best marketing services for small electronics components. So, one among the boards was a PIR Relay Module which costs around ₹180 for me. In my house, I and my brother are the laziest and we don't use to turn off the lights once we leave the room. I wished I could install the board to the existing switch so as to make the lights automatic.
Coming to the working principle of PIR Sensor, it usually consists of two special materials (Pyroelectric) which are sensitive to Infrared waves. When no change or motion occurs both the materials since the same amount of IR and stays idle. But as soon as there is a motion of a human or any changes which produces a difference in heat, the two material senses different variation. Consider it like this, when a person enters a room the first material gives the first output followed by the second material, and when he/she leaves the second materials gives the output first followed by the first material. When entered, gives a positive differential change, when left, gives a negative differential change. This is basically how a PIR Sensor works. Also, the module has got an Operational amplifier, a potentiometer for changing the sensitivity and a Fresnel lens for the material to sense the IR.
Now the run time, I undid the bulb wiring and installed the module as per the description in the module. For my amusement, the bulb turned on successfully the moment I entered the room. But sadly, the bulb doesn't turn off immediately. But after 36 seconds the thing turned off. For me, this was not an efficient way so I removed everything and reinstalled the bulb. There was no way to control the time delay for the module. I did some reverse engineering and found that changing a couple of resistors and capacitors would adjust the time delay, but it seems cumbersome. So I failed in this attempt but still found and studied something useful and hopefully serve you the same.
See You.
Recently I received a few boards and accessories which was ordered previously through Ali Express. Don't mind if I say that AliExpress is one of the best marketing services for small electronics components. So, one among the boards was a PIR Relay Module which costs around ₹180 for me. In my house, I and my brother are the laziest and we don't use to turn off the lights once we leave the room. I wished I could install the board to the existing switch so as to make the lights automatic.
Coming to the working principle of PIR Sensor, it usually consists of two special materials (Pyroelectric) which are sensitive to Infrared waves. When no change or motion occurs both the materials since the same amount of IR and stays idle. But as soon as there is a motion of a human or any changes which produces a difference in heat, the two material senses different variation. Consider it like this, when a person enters a room the first material gives the first output followed by the second material, and when he/she leaves the second materials gives the output first followed by the first material. When entered, gives a positive differential change, when left, gives a negative differential change. This is basically how a PIR Sensor works. Also, the module has got an Operational amplifier, a potentiometer for changing the sensitivity and a Fresnel lens for the material to sense the IR.
Now the run time, I undid the bulb wiring and installed the module as per the description in the module. For my amusement, the bulb turned on successfully the moment I entered the room. But sadly, the bulb doesn't turn off immediately. But after 36 seconds the thing turned off. For me, this was not an efficient way so I removed everything and reinstalled the bulb. There was no way to control the time delay for the module. I did some reverse engineering and found that changing a couple of resistors and capacitors would adjust the time delay, but it seems cumbersome. So I failed in this attempt but still found and studied something useful and hopefully serve you the same.
See You.
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