ijk@hropus.UUCP (Ihor J. Kinal) (01/10/86)
I was wondering is anyone had the inside track on infrared detectors or microwave detectors (e.g., those little units at supermarkets that open doors). I would like to hook one up on the outside of my house. I figure this would greatly discourage vandalism and petty theft (last year, someone stole Xmas lights off our tree outside, plus a bug-whacker light); but most important, would greatly discourage burglars to have a side of the house light up as they approached (yes, I do realize that many burglaries occur during the day, but that's another story). I'm looking for something relatively inexpensive, since I would want to install several (one on each side of the house, plus my back porch makes at least 5). The ONLY devices I've seen are 1). RADIO SHACK: infrared detector, cost about $70. Disadvantages are, that its power input is 12V (not sure if A.C. or D.C.), and it has contacts for an alarm as output, so I would need some sort of relay to control the light. 2). HEATHKIT: complete kit includes two spotlights. Obvious advantage- just replace current outside lights, and leave them on. Disadvantage, is that the cost is about $170. 3). Another alternative might be these sound switches that activate lights. I've got a couple inside the house, and they're OK, but I'm not sure how water-resistant they are. With an infrared detector, I could presumably put it inside a plastic box (I hope infrared passes thru clear plastic - anyone know for sure??????????????) and rest easier. Also, a burglar would presumably be very queit; I might have to turn the sensitivity way up, and have it triggered by street noise, air conditioner, etc. While I don't mind occasional spurious triggers (I'm not activating the burglar alram, just some powerful lights), I don't want flashing lights to turn my house into a Xmas tree year round. The infrared units seem to be ideal, supposedly triggered by specific body temperature of a person (although I wonder about the effects of a hot summer or freezing winter night; I mean, your normal skin temp is about 85 - will the detector see anything if it's 90 degrees out??? Or if it's 10 degrees with the wind blowing, will you still give off sufficient heat? The store detectors that open doors seem to have potential, unless their maximum range is 10 feet, in which case placement becomes very critical, and I might need more than one a some of the sides of the house. Does anyone know who carries something like this??? (If no one replies, I guess I'll just ask my supermarket manager). Anyone thoughts on this subject would be greatly appreciated. Thanx. Ihor Kinal houxm!hropus!ijk
daw1@mhuxl.UUCP (WILLIAMS) (01/13/86)
I saw something that might fit the bill at the local building
supply store. It was similar in appearance to the hardware used to
mount spotlights: a cover plate that screws on the electrical box with two
adjustable necks that hold the spotlights. But an "eye" is mounted between
the two bulb holders. It seemed to be standard spotlight hardware plus
this "eye" in the center hole of the cover plate. It was $20, bulbs not
included. If this is the type of thing you are looking for I'll get
the mfrs. name next trip to the store.
1
1 1
1 2 1 Doug Williams
1 3 3 1 AT&T Bell Labs
1 4 6 4 1 Reading, PA
1 5 10 10 5 1 mhuxl!daw1
1 6 15 20 15 6 1ccrse@ucdavis.UUCP (0058) (01/13/86)
> 1). RADIO SHACK: infrared detector, cost about $70. Disadvantages > are, that its power input is 12V (not sure if A.C. or D.C.), and it > has contacts for an alarm as output, so I would need some sort of relay > to control the light... > > ...The infrared units seem to be ideal, supposedly triggered by > specific body temperature of a person (although I wonder about > the effects of a hot summer or freezing winter night; I mean, your > normal skin temp is about 85 - will the detector see anything if it's > 90 degrees out??? Or if it's 10 degrees with the wind blowing, will > you still give off sufficient heat? I have had some experience with the RS IR motion detector. From what I've seen, I can tell you that, yes, they tend to be more sensitive when the difference between air and body temperature is larger. In a cold room, for example, the sensitivity may be nearly double that in a heated room. One thing which I *don't* know is if they detect bodies warmer than their surroundings, or if they detect things that are a significantly different temperature from their surroundings, whether higher or lower. I would hope for the latter, but tend to suspect the former to be true. > The store detectors that open doors seem to have potential, > unless their maximum range is 10 feet, in which case placement > becomes very critical, and I might need more than one a some of the sides > of the house. Does anyone know who carries something like this??? > (If no one replies, I guess I'll just ask my supermarket manager). You can get both types of motion detector from Dick Smith Electronics. They carry what appears to be a better IR detector than Radio Shaft's for $60.00, and a microwave unit for $70.00. The microwave unit is listed as having a max range of 25', both work off of 12 VDC and have adjustable sensitivity. I have dealt with DSE a couple of times and had good experiences so far. They have stores in the bay area and LA, but seem to work mostly through mail order. They can be contacted by phone at (415) 368-1066 (inquiries) 1-800-332 5373 (orders), or by mail at 390 Convention Center Way, Redwood City, CA 94073.
larry@kitty.UUCP (Larry Lippman) (01/15/86)
> I was wondering is anyone had the inside track on infrared detectors > or microwave detectors (e.g., those little units at supermarkets that > open doors). I would like to hook one up on the outside of my house. > I figure this would greatly discourage vandalism and petty theft ... Most of the door opening detectors are microwave since changing outdoor illumination (i.e., movement of the clouds, precipitation effects, etc.) can cause false operation of infrared detectors. Infrared detectors are fine - INdoors. > 3). Another alternative might be these sound switches that activate > lights. Forget it - you will have a false trigger problem with vehicles, aircraft, birds, etc. > I'm not sure how water-resistant they are. With an infrared detector, > I could presumably put it inside a plastic box (I hope infrared passes > thru clear plastic - anyone know for sure??????????????) Most plastic (and glass) severely attenuates infrared energy so that a passive infrared intrusion detector will not function if the sensing element is behind such a window. If you look closely at a passive infrared detector, you will see that the covering of the detector surface is very thin, special plastic - the sensing element is directly behind this cover. > The infrared units seem to be ideal, supposedly triggered by > specific body temperature of a person (although I wonder about > the effects of a hot summer or freezing winter night; I mean, your > normal skin temp is about 85 - will the detector see anything if it's > 90 degrees out??? Or if it's 10 degrees with the wind blowing, will > you still give off sufficient heat? That's why infrared detectors are not used outdoors. Also, a person dressed in well-insulated clothing will often not be detected by a passive infrared detector indoors, let alone outdoors. The infrared detectors work by sensing a CHANGE in infrared energy over a short period of time, with such a change being interpreted as motion. Preciptation and other outdoor effects can often cause such detectable change in short periods of time, thereby resulting in false triggering. Unquestionably, you want a microwave motion detector, which is pretty much immune to all but the most severe outdoor precipitation effects. I would suggest that you forget about Heathkit and Radio Shack and try to find a commercial distributor of alarm products to visit; many larger locksmiths also distribute alarm components. One manufacturer of microwave detectors which would be suitable for yoru purpose, and which is commonly stocked is Racal. ==> Larry Lippman @ Recognition Research Corp., Clarence, New York <== ==> UUCP {decvax|dual|rocksanne|rocksvax|watmath}!sunybcs!kitty!larry <== ==> VOICE 716/741-9185 {rice|shell}!baylor!/ <== ==> FAX 716/741-9635 {G1, G2, G3 modes} duke!ethos!/ <== ==> seismo!/ <== ==> "Have you hugged your cat today?" ihnp4!/ <==