Date: Fri, 20 Oct 89 22:00:00 EDT
From: Marcus <email@example.com>
Subject: home security
Radio Shark is pretty expensive considering the quality and options
they sell. Try some place like Aritech. (1-800-432-3232 for a catalog and
make up a security company name for your mailing address) They carry much
more stuff, and have the advantage of *KNOWING* their merchandise. (Try going
to your local Radio Shark and asking them about how the controller *works*)
They have good technical support, too.
As far as the other poster's remark that a do it yourselfer might
miss something the pros might not: That's true, but a do it yourselfer can
do a lot of things the pros won't think of, or recommend. Examples are:
wireless units with magnets between the VCR and the TV (move them and the
alarm goes off - I don't sit with my alarm on when I watch movies), wireless
units in the jewelry box (a fun one), wireless (or wired, at that) units
between stereo components and stereo cabinet, etc. When I worked for a
burgular alarm company, we never did anything like that because we could
not rely on our customers not setting the darn things off constantly.
Things that do it yourselfers *DO* forget:
Horns/sirens outside, but not wired into the loop so that they can
be disabled safely.
Bells outside in cabinets where they can be reached (even if the
bell cabinet is alarmed,a bell can be totally silenced with a can
of polyurethane spray insulation)
Making perimeter alarm units hidden. If they can't see them, they
can't be scared off by them. We used to use a mix of perimeter
alarms and then at least 1/3 as many interior alarms - stuff like
between the doors to the master bedroom, computer room, etc.
Date: Wed, 14 Mar 90 18:12:00 EST
From: "ROBYN L ROBERTSON" <FSRLR@alaska.bitnet>
Subject: Re: Home security
>Regarding window grates, what are the options these days in security
>versus being able to get out from the inside quickly in case of fire
I solved a similar problem with a set of exploding security bolts. I have
not seen these in the U.S., but I expect they are available. They are
available in varying diameters and treads, with shear points set at the
level desired for the given application. Detonation is accomplished by
running a fairly low voltage current of a minimum amperage determined by the
number and type of explosive shear bolts used(the electrical line activating
the detonation should have a predicted resistance, depending upon the type
of shear bolts, and whether they are wired in series or parallel: CAUTION:
UNDER NO CIRCUMSTANCES USE A NORMAL VOM OR DVM TO CHECK LINE RESISTANCE, USE
ONLY A 'BLASTING OHM-METER') through the detonation curcuit.
In event of a compromise of electrical power to the shear bolt system, it is
customary to include a back-up power supply, the design and implimentation
of which I leave as an exercise to the student. In practice, this sort of
emergency escape route is an escape route of 'last resort'. You do not want
such a pathway, in extremis, to be compromised.
I might note that in the applications where I have seen such bolts used,
there has been very narrow access to the area under security, and so casual
visitors setting off the escape-route shear bolts was a non-existant problem.
In a residence, I would suggest that it might be appropriate to add a fast
(perhaps three digit?) number-pad lock on each emergency exit so armed. I
also warn that the heads of the bolts, which contain one wire(the bolt body
providing 'ground'), should be installed in a manner to preclude tampering.
Finally, if detonation will allow explosion debris(very minimal, in most
cases) or the security grate to intrude upon property not under the owner's
control, there may be legal implications should someone be injured. I have
no particular expertise in this area, but I can easily envision, at least
in the litigious U.S, some creatin of a felon, minus three fingers on one
hand, standing in court beside his equally mercenary American attorney,
filing for damages sufferred when your security grate blew up in his face
while the gentleman was otherwise occupied attempting to cut through one of
the shear bolts holding said security grate in place.
P.S. Normal precautions re isolation and segmentation of the overal system
into descrete sub-units should obtain here, as one would expect. It does
no good to have a fancy system to blow all thirty-five windows in a structure
free of security grates if a fire on the first floor burns the insulation off
critical connections, leading to a short which disables the entire system.
Date: Thu, 22 Mar 90 02:00:00 EST
From: "Joseph C. Pistritto" <firstname.lastname@example.org>
Subject: Re: Home security
Well, there ARE other techniques that work against LEXAN. In particular
heating it up will make it bend, allowing sheets to be bent and popped from
the window frame. They used LEXAN in the 'escape-proof' new jail in Towson,
Maryland several years ago. Took the inmates about 3 months to figure away
to make a blowtorch from an aerosol can, point at lexan, heat for several
minutes, kick out panel. They put bars in after that...
With suitable reinforcing, and by keeping the panes small enough, this
problem could possibly be avoided. An interesting possibility is making
those 'colonial' style windows where the panes are about 8 inches by 12
inches, with the panes being Lexan and the normally wood barriers between
pains being made instead from steel would probably work nicely, without
even having the 'look' of security, if that's what you want.
Joseph C. Pistritto HB9NBB N3CKF
'Think of it as Evolution in Action' (J.Pournelle)
Ciba Geigy AG, R1241.1.01, Postfach CH4002 Basel, Switzerland
Internet: email@example.com Phone: (+41) 61 697 6155
Bitnet: firstname.lastname@example.org Fax: (+41) 61 697 2435
Date: Tue, 30 Oct 1990 18:54:00 -0500
Subject: Re: Imposing fines for false alarms (Was: DIY Wired Alarm Systems
> a dedicated leased circuit from your house to the
> alarm company.
This is definitely the wrong way to do it. A standard technique is to share
a phone line between voice and alarm signaling so that you can use your
regular phone line for this.
The way that it works is that you have a special box on your premises hooked
to your alarm system and contract with an alarm service. The service
contracts with the phone company so that gear in the switching office
listens to your line for the special tones from your alarm sender.
When you have an alarm the sender emits audio squeals that tell the listener
gear about your alarm (mine has 8 different codes). The listener gear
tells the alarm monitoring company. Their computer sends back an ACK that
is sent back to your alarm box; your box keeps crying until he gets his alarm
When there isn't an alarm the phone company polls your box about twice a
minute to make sure that he's alive and that the phone line is uncut. This
polling stops when you go off hook so that you don't hear the squeals; when
you're off hook the company knows that your line is alive. In the case
of an alarm your box will squeal, off hook or not, so busying the line won't
help a burglar.
This works quite well. When our phone line was accidentally cut the
monitoring service found out within 60 seconds and rolled the cops. I
have codes for "unattended burglary", "panic burglary" (i.e., I'm
home at the time and I can see the whites of their eyes - the cops don't
screw around when they get this code...), and stuff like "household problems".
(Breakers popping, water on the floor, freezer hitemp, etc. are
"household problems"). The alarm company has a seperate action list for
each alarm cause. For some they call the house to verify. For others they
roll without calling. For Household problems they have a list of folks to
call until they get someone who can go over and fix the problem.
Cost is about $25 a month, roughly. This gear has existed for at least 3
years, probably a lot longer.
Date: Mon, 3 Dec 1990 12:28:00 -0500
From: "J. Spencer Love; 237-2751; SHR1-3/E29 06-Nov-1990 1006" <email@example.com>
Subject: Re: Alarm company leased lines (was: Imposing fines for false alarms)
> When there isn't an alarm the phone company polls your box about twice a
> minute to make sure that he's alive and that the phone line is uncut.
I can immediately see a way to defeat this. Short the line near the house.
If the loop is at all long, the resistance of the wires between the short and
the central office will fairly reliably prevent detection of the short, which
will look like the line is off-hook. I *guarantee* that an alarm box squeal
will not get past a short.
One thing that would get past a nonmalicious short in the event of an alarm
would be to ground (unbalance) one side of the line (a similar technique is
used by pay telephones), but once the short is in place the wires between the
short and the house could be safely cut. In fact, a 600 ohm resistor could
thwart both short and open detection.
No special gear or knowledge is needed to use this strategy, which can be
applied at the side of your house unless you also wire your yard for intruder
detection (help, officer, there's a killer poodle pissing in my flower bed).
A separate security company leased line, on the other hand, has at least the
possibility of being concealed.
In the ISDN era, special hardware will be required to simulate a working line,
since a continuous digital dialogue is possible over the 16Kbit call-control
channel even when two other conversations are in progress over the same wires.
A short and cut wires look the same at the link level.
To defeat Mission Impossible burglars, public key encryption can be used
between the house and the security company, a la "smart cards". The security
company can require a different response to each challenge and the
transformation can be kept secret. However, it'll be several years (at least)
before ISDN is widely available in the U.S. to residential subscribers.