door sensors

[green beret]

Everbody should know about those sensors that they have(on doors), usualy called door reads, and usualy at the top of the door. I am wanting to know is there a way to trick these things into thinking, that they are still closed so that the alarm will not go off. What about Al foil, on the sensors? Or running a wire from one sensor wire to another so it give the illusion of a closed circuit.Any ideas?

[SATANIC]

you want to keep the two wires apart! (usually) use a strong magnet to put in place of the magnet that would have been on the door. this keeps the switch open.

some reed switches do the opposite, the magnet keeps them closed, but if you use a magnet, then you will always keep it right, no matter what kind it is. some one on the forum has posted a diagram before, if they do not come forward, i'll try to make one.

[Predator]

<a href="http://www.angelfire.com/co/WildEyedPsycho/alarm.gif" target="_blank">Picture of Magnetic Reed Switch. Right click on this link, choose "Copy Shortcut", and paste into your browsers URL address bar.</a>

Carefull though.. some people have said that some of the reed switches work in exactly the opposite manner

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You should know by now that geoshitties doesn't allow pictures to be shown from other webpages. :rolleyes:

[This message has been edited by Predator (edited September 11, 2001).]

<small>[ April 07, 2002, 10:12 PM: Message edited by: nbk2000 ]</small>

[A-BOMB]

One way to find out get a giant 300 lb lift magnet and put one pole next it then run away and hide and see if the cops come if not that is the right pole of the magnet now go tape it in place and get that big screen that you saw or it was a wrong pole and they got you on camera or the systems off.

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live by the bomb
die by the bomb

[green beret]

Thanks all. That info will be very 'usefull'!

[atropine]

Not entirely related but the sensors on sliding doors, ive got to transmit at a high bandwidth for a good 50 miles. They can transmit up too 4000 miles but as they are line of site and the earth is like a dead jelly bean it tends to maker it difficult if not impossible. Oh cos they is high bandwidth you get an almost digital sound quality.


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all wize men have unwize fantasies &lt; ^ &gt;

[EventHorizon]

small neodymium magents work great



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-chance favors a prepared mind-
PGP ID 0x147CEF54

[Anthony]

Am I being dumb or were you shit faced when you posted that Atropine?

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"Shit happens. Get a fucking helmet"

[atropine]

well a little poo'ed maybe. But maybe a better metaphor would be called for. "Because the earths surface has a relatively step curvature" or something.

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all wize men have unwize fantasies &lt; ^ &gt;

[r69o420b187]

yET ANothER k3WL HO"s B1tE THE duZt.

<img border="0" title="" alt="[Wink]" src="wink.gif" />

BTW, it's for idiots with names like this that the member # comes in handy. :D

<small>[ April 03, 2002, 11:37 PM: Message edited by: nbk2000 ]</small>

[Zambosan]

The polarity of the magnet is not an issue; reed switches contain a ferromagnetic metal strip (iron, etc.) that is attracted to the magnet and makes/breaks contact with another.

<small>[ July 18, 2002, 01:27 AM: Message edited by: Zambosan ]</small>

[Snipie]

Just some information….

Some Reads can be build in, in the door, and with a little painting it is undetectable for the eye, but is you make a magnet sensor (with a Hall-effect generator) you can scan the door for magnets.
Another thing, sometimes they put a resistor in the read, so if you shortcut it, the resistor will be gone, and the alarm system will detect that.
So if the read is N.C. (Normally Close) it is possible to set the alarm off by shorting the read.

A time ago, I was thinking of a system witch record the signal what the sensor (read, or something else) gives to the alarm system, and than play it back, but if the alarm system changes his signal every now and than, it would be worthless (that’s the reason I never finished the device).

<small>[ April 04, 2002, 04:12 PM: Message edited by: Snipie ]</small>

[nbk2000]

I've thought about the usefulness of an ECM package to detect the presence of alarms and security hardware.

This would consist of a magnetic field detector, AC and DC field detector, ultrasonic audio convertor, RADAR detector, and several other sensors.

These would detect magnetic switchs, pressure mats, light beams, ultrasound and microwave motion detectors, locks/chains/bars through non-metal doors, and other useful burglar intel. :)

All conveniently packaged in one "Tricorder" style unit to allow for rapid detection of most threats to intrusion.

This would have to wait till I win the lottery or rob Fort Knox, unfortunately. <img border="0" title="" alt="[Frown]" src="frown.gif" />

[green beret]

Wish I had all that stuff NBK, but wouldnt that make it a little to easy <img border="0" title="" alt="[Wink]" src="wink.gif" /> , I like doin it the old fashioned way, that is of course unless they have very high security alarm systems. <img border="0" title="" alt="[Frown]" src="frown.gif" />

[FragmentedSanity]

GB - wouldnt the old fashioned way be to just shoot/stun/bash whoever had the key?
But seriously - how many places are there that only use reed switches, are you sure there is no other system? or have you found a wy around it already?
but if I were you Id invest like $10 and go to a dick smith or a tandy or radioshack or something similar and buy a couple of reed switches and play with them - a 9volt battery and a LED will do for your alarm and you can get the switches in both normally open and normally closed configurations - better to try these things out at home where you cant get busted for it.
later
FS

[A-BOMB]

When I want to open a door that I think is wired, but first you need the right tools like, a razorblade on a stick and a very large magnet, double sided tape, a hall type device and a infrared detector(can get all at radioshack). First get out the infrared detector and look around to see if there are motion detectors, then take the hall type think (sences magnets and there polarity) once the polarity is found you take the large magnet to the place where you found the switch and tape it in place, then take the infrared detector to the outside edge of the door, to check for infrared optical switches on the inside of the door. Then put the razor blade at the top of the door on the side with the hinges, to check for contact switches on the hinges and door frame then, the door can be opened with fair certanty of it being trip proof.

[Arkangel]

Since motion sensors are mentioned, what's possible to do with them. In quiet moments in places that have them I occasionally try to sneak round mission impossible stylee. However slow and patient I am, I fail each time.

[skeleton_keys]

Most magnetic switches in use are Normally Closed, so as long as the circuit's complete, the alarm doesn't go off. Normally Open switches are rare because people realized all you had to do was cut one of the wires, and the switch becomes useless.

If you can, measure the location of the magnet for later reference. If you can't, or aren't sure if your targeted door has a magnetic switch, get a really *good* compass, and run it *very* slowly around the edge of the door. If the needle starts going crazy, you've found where the magnetic switch is. The magnet will always be mounted in the door/window, and the switch will always be mounted in the frame. With doors, you can then drill into the door and press your own tubular magnet against the one mounted in the door, then slowly open the door so your magnet slides under the switch. As long as your magnet doesn't move, the switch will never know.

As for jumpering a switch, this is tricky. As some other members pointed out, a lot of alarms measure the pulse rate of the electricity, so if the circuit becomes slightly longer, it sets off the alarm anyways. But if it's cheap, old, or just doesn't have that feature, and you can access the wires, just bare some of the wire inside the insulation and run another wire between them. Of course, this only works for Normally Closed switches. This works well if you have access to the alarm during a time when it's not active. Or you could just pull the wires off the switch and twist them together. Or unscrew the magnet from the door, and superglue it to the underside of the switch. This gives the appearance that everything is normal, while still allowing you to open the door safely. Hope this helped.

[skeleton_keys]

Forgot to mention, with windows (especially in modern apartments, since they go for the hidden, aesthetic recessed switches instead of the ugly exposed box-type switches), you can do the same trick with a compass to find the switch, then pry up the window with a pry bar a fraction of an inch. Slipping a flat magnet (available from good hobby shops everywhere) under the window should hold the switch in place, allowing you to pop the window the rest of the way open.

[green beret]

Fragmented sanity- yeah I guess your right but what I really meant was the "Smash and Grab" routine but I also enjoy the challenge of a modern alarm system, my choice of method and tactics depends totaly on the situation.

Arkangel, motion detectors are most sensitive to movement going away or towards them, I guess manuvering around them without going towards or away to much, try going parrallel to the sensor.

[nbk2000]

The better quality alarms use "balanced" switches. THis is where the magnet pulls on a magnet with an opposite polarity that is attached to the tensioned reed.

The switch is of a normally open, with a "guard" circuit that is normally closed. Don't ask me to explain that, since I don't know.

Anyways, what happens with the switch is that, if you attempt to substitute another magnet, it will either be too weak, in which case the circuit closes, or too strong, in which case it also closes.

Hence the "balanced".

It's a near impossibility to get a magnet of exactly matching strength, positioned at exactly the right distance, and the right time, to avoid setting off the alarm.

With PIRs, the best thing to do is avoid being "seen" by them. They work by detecting the movement of a hot object (your body) moving across a cooler background.

However they can't see you through solid objects.

If possible, use an object already in the room as a shield and push it along between you and the detector. The object will be at the same ambient temperature as the room, thus not enough to set off the detector.

Also, the PIR is most sensitive to objects moving across it's field of view. Objects that are moving directly towards the PIR are harder to detect since only one of the two detector elements will be sensing you.

<img src="http://server3001.freeyellow.com/nbk2000/PIR_Sensor_WM.gif" alt="" />

Also, PIRs have "blind spots" in their fields of view. The gaps are large enough to move through sideways at a distance, but knowing where they are is impossible unless you have opprotunity to test the PIR FOV while the alarm is off, like during business hours.

I've heard it suggested that shoting the PIR will destroy it before it can alarm. How you do this without getting noticed by the shot is your problem.

Also, I'd like to remind you people that there is now a forum dedicated specifically to discussions such as this known as "Lockdown!". This is what it was intended for, to remove such discusions as this to a dedicated forum so that the EW Forum could remain strictly about E and W. <img border="0" title="" alt="[Wink]" src="wink.gif" />

<small>[ April 07, 2002, 10:08 PM: Message edited by: nbk2000 ]</small>

[green beret]

Damn I had that motion detector movement thing backwards, does anyone think that "expedient breaking and entering" is a good book? If anyone has it in PDF could they put it on the FTP, I only have acrobat viewer so I cant convert it to PDF, otherwise I would.

From what I have read of EBE it seems like a good book, what do you all think....

[nbk2000]

The B&E book is also on the FTP. I believe it's even called "B&E". It's in PDF format.

I've read it and it's OK, but some things in there are TOO over the top. Like the constant reference to specialist on a "team". :rolleyes:

If you have a "team", you're either government or high-level organized crime. In which case, you don't need some crappy book from paladin press to tell you what to do.

I'd like to see a book dedicated strictly to solo B&E that gives concrete details on all manner of lock and alarm defeats. And that SHOWS you with pictures.

Maybe when I win the lottery I'll set up a criminal research foundation like RAND.

[skeleton_keys]

With PIRs, it's not so much that it senses a hot body against a cooler background. It senses the ambient temperature, and then detects *any* rapid change in that temperature detection area. You could leave a non-moving space heater in front of the alarm, and remotely switch it on suddenly, which would set off the alarm, even though the heater never moved. It's designed to adjust to slow changes in temperature, which is why you see that ever-popular trick in the movies of slowly turning the thermostat up until the room matches your body temperature. (After all, you wouldn't want it going off because the sidewalk outside your window was cooling at night, or to have to freeze during the winter because your dang PIR wouldn't let you turn the thermostat above 70 degrees without setting it off.) If something passes by the PIR's detection zone within a few tenths of a degree (depending on the sensitivity of that particular model) of where the ambient temperature is, it won't sound the alarm. Like the previous post said, PIR's don't work through solid objects, including glass. Anything that blocks your temperature from being detected will fool the alarm. I've been wondering if there is a chemical (or mixture of chemicals) that could line a suit, and control your outward body temperature (a la "The Saint"). The guy that invents that could walk past most of the popular motion detectors on the market today.

Another interesting note is that most PIR's (and other motion detectors, for that matter) have a safety setting to not detection motion from anything that may be somewhere around 40 lbs. or less, I believe. That way, your pet doesn't always set off your detectors when running around the house at night. Perhaps you could work with a midget? :)

[Anthony]

What about making up a suit out of mylar (survival blankets)? Problems I forsee would be it would be noisy to move about it and also you'd soon overheat because that bodyheat has got to go somewhere.

[nbk2000]

The better quality detectors (Museum/Military) will detect a variance of 1/10th degree C from ambient.

Commercial one's like Rat-Shack will do 1 degree C.

And, like you said, a radiator will set it off too. But that's because there's a moving mass of warm air rising. Air radiates heat too.

The thing with pets is dependant on the setting of the alarm. If it's a homeowner alarm, then it probably has a pet zone. Commercial alarms aren't going to have that.

And the mass of a human is much larger than a 40 pound animal, thus we give off much more IR radiation. I believe a human at rest gives off as much heat as a 200 watt light bulb.

I see two possible ways of defeating a PIR that doesn't involve funky suits.

Either curl up into a ball and FLY past the PIRs field of view faster than it can respond (something like half a second). Only work for crossing doorways in view of the PIR. Use a skate board or something with a running start.

Or, somekind of motorized platform that will move you veeeeeerrrryyyy slowly across the FOV of the PIR towards somewhere it can't see you. I'm talkin inch a minute time here folks. Much slower than would be possible for you to move yourself.

This way, you're moving too slowly to cross the PIRs thresehold of detection.

A mechanics creeper comes to mind.

I've also thought of a aluminized mylar tube filled with cooled helium (NOT liquified, duh!). Helium is the most effiencent gas for absorbing heat. Between the mylar reflecting back in the heat, and the helium absorbing the rest, you shouldn't have enough left over to set off the alarm.

This presupposes you can get the tube from point A to point B without setting off the alarm in the first place.

Experimentation is in order.

I've already tested my Rat-Shack portable PIR alarm with a sack of ice. Didn't go off. So at least being COLDER than ambient worked with it. But this is a $20 alarm we're talking about folks.