Sensor light

We had a security light installed for my mother at her back door which worked fine for a couple months. Now when someone walks up to the door it no longer comes on but when you walk back to your car then it comes on. How do we fix this? TIA
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Put a sign up that says walk backwards towards the door???
;-]
Sounds like you need to adjust the sensitivity....
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Zillions of things cause this. Shall we pick a few. Read the direction to see if there is a sensor adjustment. COLD on el cheap o stuff Aiming of the sensor
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Dinah wrote:

Stopped working when it got cold did it? Common problem many of them become less sensitive when cold. You may be able to adjust it.
--
Joseph Meehan

Dia duit
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Joseph Meehan wrote:

sensitive when it gets hot outside. When everything is near 100 degrees, including your body, the sensor can't tell the difference.
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I had so much trouble with cold I tossed it in the trash. in the winter every car going up the street would trip it.....
in the summer it was dead. not worth the effort
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I have 2 and the work! I live in FL. so it never gets to 100. but a sensor has nothing to do with temp!!!!!!! Try again!
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You sure about that, Mr. Science???
The "motion sensing" feature on most lights (and security systems) is a passive system that detects infrared energy. These sensors are therefore known as PIR (passive infrared) detectors or pyroelectric sensors. In order to make a sensor that can detect a human being, you need to make the sensor sensitive to the temperature of a human body. Humans, having a skin temperature of about 93 degrees F, radiate infrared energy with a wavelength between 9 and 10 micrometers. Therefore, the sensors are typically sensitive in the range of 8 to 12 micrometers.
The devices themselves are simple electronic components not unlike a photosensor. The infrared light bumps electrons off a substrate, and these electrons can be detected and amplified into a signal.
You have probably noticed that your light is sensitive to motion, but not to a person who is standing still. That's because the electronics package attached to the sensor is looking for a fairly rapid change in the amount of infrared energy it is seeing. When a person walks by, the amount of infrared energy in the field of view changes rapidly and is easily detected. You do not want the sensor detecting slower changes, like the sidewalk cooling off at night.
Your motion sensing light has a wide field of view because of the lens covering the sensor. Infrared energy is a form of light, so you can focus and bend it with plastic lenses. But it's not like there is a 2-D array of sensors in there. There is a single (or sometimes two) sensors inside looking for changes in infrared energy.
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On Fri, 27 Jan 2006 02:27:22 GMT, "Dr. Hardcrab"

Good explaination
The actual detection is simple. Look at the lens on the sensor. See the sectioning in the lens? That is a grid of different thicknesses of plastic that pass differing amounts of IR energy. Imagine pointing a flashlight through a picket fence. If you stand still there is a steady state, either light or dark. As you walk along the level switches as the light moves across the pickets. That is the same effect as the ridges on the lens. The sensor itself only responds to levels that change. If it sees enough changes in X miliseconds it trips. I usually have to crank down the sensitivity in winter (florida) and turn it up in summer to get similar performance. I have over a dozen motion detectors around the house. I have bought more than I can count and Home Depot has replaced a bunch for free. Direct sunlight will kill them.
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wrote:

my flag waving will set the light off! So will my dog. and a small tree when it is windy..... and a hanging plant moving.
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Have you ever seen IR photography? Heat doesn't have to burn you to be there. The background heat is interupted by your flag or tree. The same principle applies as the target moving across the grid. If there is enough delta between air and water temperature, the heat coming off my pool will turn on the light with the slightest breeze just stirring up the heat. The water is still slick calm. The only thing "moiving" is the heat.
The dog, (raccoons, possums, cats) is a warm body animal moving across the lens field
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wrote

You obviously didn't read my explanation, so out you go!
buh-bye
*PLONK*
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wrote:

I notice that with a motion-sensing switch in my garage. It becomes less reliable in the summer.
--
Mark Lloyd
http://notstupid.laughingsquid.com
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Tell all your friends to walk backwards when they come to the door... <lol>
It may have moved a little from winds. Adjust the angle, there is usually a sensitivity control too.
Of course if you got a tree branch growing near it, or some other change that can affect it too.
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