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Decent Motion Sensing Lights?
Above asks: "At my previous house I purchased a number of motion sensor lights to replace the standard flood lights. I simply went to the nearest Home Depot and bought a mid range model, and they worked great. Since then I've moved, and in the new house I did the same, and got some Heath-Zenith units from Home Depot. They were junk (came on all the time for no reason). I adjusted two different units to no end, they simply didn't work. Since that was basically all Home Depot carried, I went to Lowes, and got a Regent Lighting unit. It was better, but not by much. I want my back yard to be relatively sensitive, triggered by the dogs when we let them out, but the front yard to be insensitive, triggered only by a car or the close approach of a person. Where can I get a good quality, motion sensor flood light? What are the secrets to aiming and adjusting them so they work right?"
Remember who paid for all those annoying pop-up and pop-under ads when they first came out? X10 are the primary reason all browsers come with popup blockers these days. Their internet marketing tactics stink.
I won't support them. And I urge others to do the same.
the growth in cynicism and rebellion has not been without cause
Most of the sensors have a plastic "light guide" in front of them that breaks the sensed area into zones. It is the changing difference between the zones that triggers the sensor. Try taking one of them apart and you'll see either variations in the lens plastic, or even a set of physical baffles between the outer filter and the sensor itself.
(You can actually walk by most IR sensors without setting them off if you move VERY slowly, which is why better quality alarm systems use radar or specific thermal level monitoring rather than just a change).
Which brings us to aiming. Most of the time the zones are arranged to be more sensitive to side-to-side motion than up/down. So if you have one oriented 90deg out of "true" then it'll be rather insensitive except in a narrow band. (This is a good way to limit the area of coverage of a sensor without having to break out the masking tape).
Speaking of which, the height and angle of the sensor makes a big difference for the same reason.
So I would recommend taking one apart, figuring out the zone layout and adjusting accordingly. (Heck, you can even just set one on a table and see what area it "sees" and how sensitive it is to motion in that area, then turn it 90deg and try again).
Most of the sensors have a plastic "light guide" in front of them that breaks the sensed area into zones.
Its not a light guide its a plastic fresnel lens with multiple elements which focuses light (actually heat) from various "zones" onto the sensor.
It is the changing difference between the zones that triggers the sensor.
Nope. The sensor is made from two seperate pyroelectric elements which are mounted side by side. It is differences between these two elements which triggers the device. This could be from the same zone or different zones. Sun light and other ambient light (heat) changes will affect both elements equally (you hope) so that they don't trigger the device.
Try taking one of them apart and you'll see either variations in the lens plastic, or even a set of physical baffles between the outer filter and the sensor itself.
(You can actually walk by most IR sensors without setting them off if you move VERY slowly, which is why better quality alarm systems use radar or specific thermal level monitoring rather than just a change).
Which brings us to aiming. Most of the time the zones are arranged to be more sensitive to side-to-side motion than up/down.
The are all like this due to them being two element devices.
So if you have one oriented 90deg out of "true" then it'll be rather insensitive except in a narrow band. (This is a good way to limit the area of coverage of a sensor without having to break out the masking tape).
True.
Speaking of which, the height and angle of the sensor makes a big difference for the same reason.
So I would recommend taking one apart, figuring out the zone layout and adjusting accordingly. (Heck, you can even just set one on a table and see what area it "sees" and how sensitive it is to motion in that area, then turn it 90deg and try again).
The biggest difference between the systems you can buy is the shape of the fresnel lens. You can have just one main zone or lots of sub zones or a combination of both. Most good systems will give you a diagram of the size and position of the zones which you can use to choose and position them.
wot no sig