I recently bought a IR sensor. I used a a usb cable wity negative and positive terminal ends to power it. I tried to increase its sensitivity but then it would always show that there is a obstacle. I tried to point it to the sky and it still shows the error. When i lowered the senstivity it works fine but i really want higher senstivity. What should i do? Help me
Turn the blue knob clockwise and the red knob down. That is about the best I can answer as I am not clairvoyant. You need to let us know what you have and how you connected it, a schematic is a great way of showing that. I have about 9 different IR sensors here and I do not think any of them are the same as yours. Also show the source of IR light.
unfortunately, i brought it from a local store and i really don't have any specs about it. but i can send you its picture.
Yes please.
Thanks.. Tom... 
here:
I don't have a red knob
And we do not have the information needed to properly answer your question.
what information do you need? i would like to provide it !
The actual problem is that the signal led of the sensor (The bright red led at the left of the sensor)
keeps on when i increase the senstivity of the sensor. Thank you for the link BTW but my problem is not resolved compltely
From what I can see in your dim picture that is what I would expect. That sensor like several others has a digital output. The sensor has a comparator IC that takes the value of the pot and sets the signal On if light is brighter then the setpoint and off if it is below. You cannot get a level of light from this sensor. Your linked data sheet shows this: OUT pin is a 5V TTL logic output. LOW indicates no motion is detected; HIGH means motion is detected.
I wonder how many sensors you could buy for the price of a module?
Last time I bought a bag (the only bag I've needed) they were 5 cents each.
Thank you very much. But can you tell me how to properly increase the range of the sensor