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VAD
Location: Toronto Total Likes: 161 likes
Forgive us our trespasses
| | | | Re: Silent Alarms < Reply # 4 on 3/31/2016 5:18 AM > | Reply with Quote
| | | You can never really "detect" when one is tripped - the best you can do is look out for the sensors and avoid giving them anything to sense. The first type is a Passive Infra-Red (PIR) sensor: These can be tuned to detect up to 30' - they sense motion of objects heated to human-temperature - usually humans. If outside, they will often not be focussed at ground level to avoid cats, raccoons, etc. Generally best to avoid them entirely though - sometimes they have little LEDs that light up or change colour when tripped, and sometimes they will make a little click, but you can't trust that they will. The second type is door contact sensors: These are usually magnetic reed switches, and will have one half installed on the door, the other on the frame. This way, when the door opens, the two separate and it triggers the alarm. Obviously don't open a door with one of these on it - but if you are in a secured facility, after every door you open inspect the inside of the frame and the other side of the door for one. If you trip it, get far from the door, or clean out of the building if you think K9 will be called (since they can smell the doorknob and track you) [Disclaimer: I do not own either of these images]
| -VAD |
| AdventureDan
Location: Texas Gender: Male Total Likes: 369 likes
I'm here to make wavy eyebrows and climb on stuff
| | | | Re: Silent Alarms < Reply # 12 on 4/1/2016 3:26 AM > | Reply with Quote
| | | From my experience, the PIRs are easy to spot, usually above doorways and at the end of hallways, and almost always have an LED to indicate whenever they are sensing motion. It's not bright though, so it's not terribly noticeable. A good rule of thumb is it's easier to rule out whether an alarm has NOT been activated. If you see there is an LED bulb indicator in the detector but it is not lighting up, it's safe to say it isn't active. I once walked through a doorway and then turned around to backtrack and saw a motion detector with an LED blinking. I got out ASAP and pulled away just as police pulled into the other side of the building. Other than that, what others have said, best to just be on the safe side and anytime you notice any door switches, sensors or cameras, just get out and watch to see if there is a response. Another option, is once you have decided you may have set an alarm, quickly temporarily disable any future use of the device, (taping the sensor lens, snipping a switch wire, etc.) and then next time you visit, check to see if it's been fixed. Also in case you wanna look ridiculous, walking around in a thermal emergency blanket (get em for 5 bucks at Walmart) will stop infrared sensors from detecting you. I've used this myself at my high school for our senior prank, and I believe Mythbusters did a segment on it.
| AAAAAAAAAAAADVENTURE TIME!!!! |
| blackhawk This member has been banned. See the banlist for more information.
Location: Mission Control Total Likes: 3996 likes
UER newbie
| | | | Re: Silent Alarms < Reply # 13 on 4/1/2016 8:18 PM > | Reply with Quote
| | | Posted by AdventureDan From my experience, the PIRs are easy to spot, usually above doorways and at the end of hallways, and almost always have an LED to indicate whenever they are sensing motion. It's not bright though, so it's not terribly noticeable. A good rule of thumb is it's easier to rule out whether an alarm has NOT been activated. If you see there is an LED bulb indicator in the detector but it is not lighting up, it's safe to say it isn't active. I once walked through a doorway and then turned around to backtrack and saw a motion detector with an LED blinking. I got out ASAP and pulled away just as police pulled into the other side of the building. Other than that, what others have said, best to just be on the safe side and anytime you notice any door switches, sensors or cameras, just get out and watch to see if there is a response. Another option, is once you have decided you may have set an alarm, quickly temporarily disable any future use of the device, (taping the sensor lens, snipping a switch wire, etc.) and then next time you visit, check to see if it's been fixed. Also in case you wanna look ridiculous, walking around in a thermal emergency blanket (get em for 5 bucks at Walmart) will stop infrared sensors from detecting you. I've used this myself at my high school for our senior prank, and I believe Mythbusters did a segment on it.
| When I used them after set up I would cover the LED indicator; no free rides. A good zoned PIR is extremely hard to slip by as its looking for temperature changes between zones past a certain rate. They can't sense long wave IR through many materials including glass, but maybe triggered by the material's own temperature as it breaches the zones. Proximity to these sensors effect their sensitivity. At couple feet away they're very easy to trip. Now days I go with a computer controlled cam(s) motion detector/recorder. Some stand alone units look like PIRs but are cams with flashcards and record on triggering. Truly abandoned sites don't have any these or power. I hate locations were they keep both active right until the last days when it's demoed. Sometimes getting permission to shoot, especially from the demo contractor, is much more productive...
| Just when I thought I was out... they pulled me back in. |
| LuminousAphid
Location: Lynnwood, WA Gender: Male Total Likes: 54 likes
Armchair Explorer
| | | | | Re: Silent Alarms < Reply # 16 on 4/6/2016 7:45 AM > | Reply with Quote
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| "See you guys, you never listen to me. I said there was gonna be trouble but you didn't listen to me. You guys are crazy. You know, you guys are self destructive. There's a funny farm and it has your names written all over it. But I'm gettin' out of here. I'm... I smell ice cream!" |
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