Intruder Alarms
Discussion
Something i know very little about, looking to put one in my workshop/man den.
At the moment its one door (set of plastic upvc double doors) but i shall be fitting a up & over garage door at some point. Though this will be secured from the inside it may be handy to add a extra contact sensor to it, im also thinking two PIR sensors is preferable to the one even for one room.
Though how sensitive are these as i do have a few rats about at the moment?
Seen these in B&Q which look ok + expandable
http://www.diy.com/diy/jsp/bq/nav.js...&isSear...
http://www.diy.com/diy/jsp/bq/nav.js...&isSear...
I appreciate these are cheep and you get what you pay for but........
At the moment its one door (set of plastic upvc double doors) but i shall be fitting a up & over garage door at some point. Though this will be secured from the inside it may be handy to add a extra contact sensor to it, im also thinking two PIR sensors is preferable to the one even for one room.
Though how sensitive are these as i do have a few rats about at the moment?
Seen these in B&Q which look ok + expandable
http://www.diy.com/diy/jsp/bq/nav.js...&isSear...
http://www.diy.com/diy/jsp/bq/nav.js...&isSear...
I appreciate these are cheep and you get what you pay for but........
For some reason your links aren't working at the moment.
Before you even bother fitting PIR's make sure you get rid of the rat problem.
No matter what PIR you fit you can practically guarantee that with rats the alarm will keep going off.
For a single roomed shed,den or garage etc you will need one of these or something like it.
http://cgi.ebay.co.uk/HONEYWELL-DUAL-TECH-MOTION-S...
These are a lot more stable and you shouldn't have a problem like a normal PIR which isn't really designed for the purpose and you will be wasting your money IMO.
If it's a small unit though, make sure you wind back the microwave detection to suit the size of the room as they will penetrate walls and glass which in turn can cause false activations. The instructions in the box will tell you how to correctly set them up. As in most systems you will only need one detector per room, unless you want to separate a room into areas, one detector is sufficient so long as the whole area is covered. Fitting two of these looking at each other can also cause false activations as well. So will ideally need to be placed looking away from each other.
Before you even bother fitting PIR's make sure you get rid of the rat problem.
No matter what PIR you fit you can practically guarantee that with rats the alarm will keep going off.
For a single roomed shed,den or garage etc you will need one of these or something like it.
http://cgi.ebay.co.uk/HONEYWELL-DUAL-TECH-MOTION-S...
These are a lot more stable and you shouldn't have a problem like a normal PIR which isn't really designed for the purpose and you will be wasting your money IMO.
If it's a small unit though, make sure you wind back the microwave detection to suit the size of the room as they will penetrate walls and glass which in turn can cause false activations. The instructions in the box will tell you how to correctly set them up. As in most systems you will only need one detector per room, unless you want to separate a room into areas, one detector is sufficient so long as the whole area is covered. Fitting two of these looking at each other can also cause false activations as well. So will ideally need to be placed looking away from each other.
Edited by Westy Pre-Lit on Saturday 3rd April 16:09
I know you're an installer Westy pre-lit, but have you thought of the possibility of fitting a pair of PIRs at opposite ends, looking towards each other, and connecting them with their alarm relay outputs in parallel? Assuming, for a moment, that the relay contacts stay open for more than a millisecond or two, sooner or later they'll co-incide and set an alarm state. What they won't do, though, is detect a rat both at once or sunlight glinting through cracks. Might be cheaper than a dual-tec...
I used to be Technical and Marketing Director for a company making external, direction sensing Doppler microwave units in the eighties - before Redwall and any other like devices. For 'proper' stability using a pair wired like this it was possible to more or less guarantee stability in, say, a DIY shed outside yard. Large targets, as you said, like trains and lorries were a constant threat with single units. Only in places like roofs and brick walled yards could you be certain of very low false activations with solo units.
I used to be Technical and Marketing Director for a company making external, direction sensing Doppler microwave units in the eighties - before Redwall and any other like devices. For 'proper' stability using a pair wired like this it was possible to more or less guarantee stability in, say, a DIY shed outside yard. Large targets, as you said, like trains and lorries were a constant threat with single units. Only in places like roofs and brick walled yards could you be certain of very low false activations with solo units.
Yeah thinking about it that's not really a bad idea tbh and can't see why not.
Have seen this sort of thing done on some older systems we have replaced and never really thought as to why it was done that way. Thinking about it now it makes sense so long as they both go off at the same time when somebody is in the covered area.
You learn something new everyday.
Detectors now have whitelight filter so light from a passing car or sun light shouldn't affect them...have never experienced a problem like this anyway that I'm aware of.
Have seen this sort of thing done on some older systems we have replaced and never really thought as to why it was done that way. Thinking about it now it makes sense so long as they both go off at the same time when somebody is in the covered area.
You learn something new everyday.
Detectors now have whitelight filter so light from a passing car or sun light shouldn't affect them...have never experienced a problem like this anyway that I'm aware of.
Edited by Westy Pre-Lit on Sunday 4th April 09:23
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