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?"

Sensor orientation

[itwerx]

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).

X10 is junk.. but worth buying anyway

[renehollan]

I researched the X10 stuff and bought three floodcams, extra receivers, a RF/powerline transciever, and USB RF receiver and control interfaces for a computer for about US$430.

For the money spent, it was a good deal: the cameras, though poor quality work, and the flood lights come on when sensing motion, sending X10 events and responding to X10 commands to turn on the cameras and floodlight.

However:

1) The video range is poor. Figure 20 feet max through typical household construction, and interference can be significant.

2) The motion sensors are not particularly responsive. The floodcams have the option to gate the lights based on the motion sensors and it being dark (i.e. at night), but those motion sensors are fairly insensitive, and worse, it appears that the turn off delay does not work if the light sensor detects light after the motion sensor turns the light on -- if the light reflects of a shiny object -- we have trouble with one car in our driveway if it is parked too close.

Still, being able to control the floodlights with a handheld remote or a computer is, by itself, a nice plus. The (admitedly poor quality) cams are a bit of a perk, but I wouldn't rely on them for serious surveillance (a good stationary camera will run $250 to $500 alone -- closer to $1000 when you start talking about good PTZ units).

Of course, compare this to close to $200 for a decent motion / time of day sensing light alone which I used to have.

Granted the X10 ads are annoying and I've let them know, several times, that their practices reflect badly on their products which are otherwise fair value for the money. I suppose that they remain effective, though.

Pen recommendation

[deek]

Dear Slashdot, I keep buying ballpoint pens that don't write well. I have to keep scribbling on scratch paper to make them work. What kind of pen should I get so I don't have this problem?

I recommend trying out the space pen [spacepen.com]. Containing a pressurised ink cartridge, it'll write reliably at any angle, on just about any surface. These pens were used by NASA in space, for their ability to work in zero gravity. Plus, you'll get geek cred for owning one.

Re:Simple.

[jandrese]

I had a bunch of X10 stuff for awhile, but the quality control was really bad. Appliance modules would turn off and on randomly, the motion sensor just plain stopped working after a few months, and pretty much everything gave me trouble after awhile except for the big white remotes in the freebie box they (used to?) give out. Maybe they've gotten a handle on their quality control since then, but I still don't trust them.

Flood lights are VERY annoying to thieves.

[Futurepower(R)]

"... flood lights aren't going protect your home very well..."

Motion sensing flood lights are VERY annoying to someone trying to sneak around. Annoying enough that they may consider trying another house that doesn't have motion sensing lights.

Some corrections

[Maddog Batty]

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.