,;\
l!l
PALADIN PRESS BOULDER, COLORADO
Tricks of the Bwglar by Mike Kessler
Copyright @
tro
AbrmTrde
Uy Mike Kessler
ISBN G87364-550-2 Printed in the United States of America First published in 1984 by Mentor Publications Published by Paladin Press, a division of Paladin Enterprises, Inc., P.O. Box 1307, Boulder, Colorado 80306, USA. (303) 443-72s0
Direct inquiries and/or orders to the above address.
All rights reserved. Except for use in a review, no portion of this book may be reproduced in any form without the exprcss written permission of the publisher. Neither the author nor the publisher assumes any responsibility for the use or misuse of information contained in this book.
(
CONTENTB
THE EASIC AURELAR ALARI'I SYSTEFI THE FROTEtrTIVE SHtrRT
trIRCUIT.
5
trIRCUITS
B
1l
CLNTROLS
.T7
BELLS&SIRENS TESTINE hIITH A
I"IETER.
20
5EN50R5.
23
THE FLUNEER
SWITCH..
?4
ST{ITCH.
26
THE 1'IA6NETItr
THE LEAF SWTTCH. r r. THE I{ERtrURY
t...
rr
r
2q
..........
ShlrTCH.. r....
TRAPS, THE VIBRATION
3?
DETEtrTBR
34
.. r.. r., r.
LACrN6, swITcH
30
35
HAT......
37
PROTEtrTINE 6LASS
t....
.....
i I r. 3E
DETECTOR.. AREA PRBTECTItrN DEVICES.. THE PROXII,IITY SENSBR.
48
THE PHETOELEtrTRItr
THE SHUNT
5c'
5g
a
LOCH.
59
TRDUBLESHOOTING. IHSTALLATION
62
.....
NBTEs.
spEcrAL TtrBLS, PARTS & TECHNTtrUES. EGUIPI'IENT COST
REFERENCE... ill
I
.
74
.
EO
89
I
\
FORET{ORD
Anything worth learning is worth learning well, and learning Eiol6ething well calls fsr some degree of effort, The objective of this book is to minimize that effort by avoiding the use of technical jargon, cryptic diagrarns and references to electrieal theory. However, this doesn't rnclan the information contained in this book will jurnp off the pages and burrow itseif into the casual reader's brain. The "sirnpli{ied" instructions packed with most do-it-yourself burgar alarm lrrts are usllally quite easy to follow, leading one blindly through the haphazard. installation of a mediocrel systern; explaining "how to do itr" r*ithout a word about what one is doingr oF why- As a result there are thousands of so-calteO blrglar alarms in current use, many o{ which can be defeated by the least sophisticated methods-- and aost of which will rnalfunction nithin a {ew months, often leaving the do-it-yourselfe'r with a collection of useless hardware fastened to the nal I s-
Flost burglars can easily recognize an irnproperly installedr simple to defeat, do-it-yourself lrrt burglar alarn jugt by glancing at its components: the o{ten {limsy control box, drooping wire:i, cheap shunt locks and imtrroperly e!p.U_ed window foil with sloppy connections. I'lany of these packaged kits are relatively inexpensive (cheap) n therefore increasingly comnonplace. I'lost contain essentially the lrne type of parts-- with instructions to install thern in essentially the tlnl h,ayr therefore they are relatively easy to recognize and de{eat by a number of simple methods' The most common of these methods is salled ,'jumpering. " This is a technique used effectively by burglars to ',by-pa5s" cheap or improperly instalted alarrn systems. There is a very simple countermea5ure to the jurnpering technique, but it is never explained in 'simplified" instruction manuals, and rarely mentioned in books. In order to apply this countermcrasurEr ctne must understand the jumpering techniQUEr which calls for thorough familiarity nith the nature o{ closed-circuit burgl.r rlrrm systlmr. This book explores closed-circuit ("supervised") wiring in detail, concentrating on the basic principles that govern all closed circuit burglar alarms, ranging from those found in tenement apartments and candy stores to those used in mansions and bank vaults. Once these principles are understood, they may be apptied to any type o{ closedcircuit burglar alarm system. The best way to learn from this book is to read it through fron coveir to cover, passing over any word or s;egment that seerns vgguer Br a bit too technjcal. Very often the answer ttr a question that arises in one section will be found in a {ollowing section, or in the next paragraph. None of the diagrams are scheratic: sBmE are self-explanatory pictorials, while others are simple line drawings. Each drawing is thoroughly supported by accompanying text. It is true that "one picture is worth a thousand words;,, and it's also true that one hands-on experiment is worth ,nore than a thousand pictures: The serious reader is well advised to obtain a sampling of the components described throughout this book and assemble a "bench system" (sn a workbench ffr kitchen tablel, and follow each separate
setrtion B+ the book with an actual experiment. This is precisely the teaching method used in all clagsroom and coFrespondence cgurses on security electronics-- and it works! Every str-rdent of a burglar alarm course is given a control panel, a coil of wire, one each of a variety of sensorsr a power supply and sotnEr mi=cellanecrus parts; and is guided through a nurnber of "bench experiments, " After the course is completedt the same cornponents are used in an actual installation or they remain part of a perrnanent bench system. (To be used in conjunction with the te=ting of new conponents and devices. ) It is recorntnended to readers who intend to install a burglar alarm system to set up a "bench system" first. After becoming thoroughly familiar nith each component and its particular function in the bench systemt stretch out a few yards of wirer apply a foil pattern to a panE! of glass (even a mirror), and practice troubleshooting with a test meter. To most novic€lsr a bench system is like a set of electric trains-with a serious purpose. Security electronics is a fascinating world of ultimate gadgetry, a field that presently o#fers golden opportunities to any competent, motivated individr-ral. Furglar alarms are def initely in, and the prof it potential in this business is impressive. A burglar alarm sjdeJjne can be operated out of a closet, using an ordinary trar. And the initial investment is nominal. For example, one wey to start up is install a system in y61ur gtwn homet then do the same for a friend or neighbor-- at a fair price. The price should at least recover the cost of both sets of components, enabling the purchase of toorEr equipment, thus an inventory is established with practically no cash investrnent. Each subsequent job generates a profit while providing valuable experience. As your proficiency grops, so t*i1l your income. Thousands o{ profitable installation companies have started up in exact-1f-ElFway; many of them are highly sutrcessful today-- and there's plenty of room for more. The techniques and equipment described in this book are not restricted to residential installations, but apply to commercial premises ag well. In factr corntnercial premises are usually easier to nire and offer exceptionally high profits tn the Jeasing installer: In a leasing (installation) arrangementt the initial charge should absorb the cost of equipment; the system remaing the property of the installer, who agrees to provide service and maintenance under contract (payable monthly. l Service contracts ghould not provide for {ree service when danrage or tampering is the cauge of a problem. Leaged burglar alarm service contracts range from 15.OO to 5OO.OO per month, depending g'n the size and sophistication of the individual system.
ldhether the reader intends to install only his (or her) own burglar alarm system or to strike out on a nelw careerr this book is a good place to begin. The next step is to assemble a bench system and get Bome hands-on experience. Each step thereafter will be rewardingi in personal satis{action, and cash savings-- or handsome profits. Vi
THE BASIC BURELAR ALARI.I
the on arto
ety ded
etreth
A basic burglar alarm system consists o{ three separate segments, the bell cireuit, the control pennl, and the protective circuit. The separate segments are wired togethe'r as shosrn in Fig. l-1. PNOTECTIYE EHCLOSURE
arflr
ly
COHTNOL
t
e
al
I
t :;
1il
can
CINCUIT
l
ten5--
it
PROTECTIVE
IilSTNUNEHT
+
f -',---------.'' rtl
./ BELL CIRCUIT
<+-.,,
AELL EFTTERY
PNOTECTIUE
CIRCUIT ERTTENY
(3 volts) COHTROL CBEIT{ET
Figuru l-l The bell, an B" circular gong rrith a motorized hammer trn its undersidet is normally enclosed in a protective steel cabinet, which should be securely mounted to an exterior wall, high enough to be inaccessible to tarnpering. A pair of 16 to 14 gauge wires are attached to the bell ootor's terminals, drawn through a wiring hole in the back of the housingt drawn through a hole bored through the mounting surface and into the premiges, where they are routed to the control fenrl. The control pentl is a square, steel electrical cabinet with a keyoperated ON./BFF switch mounted cln its face. This cabinet is securely fastened to an interior wall, somewhere in a convenient, preferably concealed location within the prernises. Inside this cabinet are the contror instrurent, which ig the "brain., of the system, and a 6 volt battery to energize the bell.
The protGctive circuit is a pair of 22 to 2O gauge wires, which are routed through the interior of the premises. Although none are shown in this diagramr' the variousi sensors (switches, detec[,ors, trap circuits' etc. ) used to monitor anticipated points of entry, twindows, doors, etc. ), will be wired into the protective circuit. The protective circuit must be routed so it passes directly acrclssr or- close to each point to be protected by a s€lnsor. One end o{ the protective circuit is connected to the control panel. At the other end is an independent_ pol'.er supply, consisting of a pair of l'5 volt ignition cells'EE--T€sether to form a s volt battery.
As mentioned above, there is a separate pohrer supply, (a 6 volt,
heavy-
duty lantern battery), inside the control cabinet for ringing the bell. The protEctive circult porer supply does not serve thr bell circuit in any way!
Fig, 1-2 is a closer look at the inside o{ a wired control panel: Fastened to the inside of the cabinet door is the cnntrol. instrunent, a circuit board upon which are mounted two electro-mechanical relays, shownasA&8.
Fl
o
l!
o
o n o
rl
6 Volt Bat tery
Fisuru l-2 Situated between these two relays is a hole through which the rear gection (body) o{ the ttN./BFF key-switch protrudes. A pair of wires (not shonn) is pulled through this hole from behind the board and connected to the key-switch. Situated below the relays and key-switch is a connecting strip with sixt separated terminals, numbered I thru 6. Terminals I & 2 are addressed to Relay Ar which is the bell relay, Terminals 3 & 4 are also
vyll. in
1E
addressed to Relay A. Terminals 5 & 6 ar€! addressed is the prottctive circuit relry. Note the connectionstoto Relay B, which inals: The bell circuit wiring is connected to Terminals thesn termvolt battery; (for the berl), is.onnected to Terminars I & ?. A six protective circuit is connected to Terminals s & 6. The s & 4. The wiring for the bell and protective circuits is drawn through ,,knockout,, holes rear of the cabinet' The 6 volt battery is attached to Terminalsin the s &4 by a short pair of 16 to 14 gauge nires. rmagine that the components covered thus far are set up .,n a test bench' arranged as shown rle've in Fig. 1-1: Rotating the key-gwitch to the CIN position will arr the systemr-meining it is'iet up,, to function as a burglar alarn. The rray tn activate the alarn is to somehon interrupt the flow of current through the protective circuit, nhich may be done either by disconnecting the battery-- or cutting a wire. lowing is a detailed explanation of how the control instrumentThr.folgoverns the separate functions of the belr ano frotective circuits, Relay A is the bell relay- hlhen the properly rated power source is applied to it, (6 volts in this example), its contacts are purled together, "latching" in place and proriding a conductive path between the Power strurce (at terminals 3 & 4t and the betl. Thera are two opens in the path between the power supply attached to Terminals s & 4: one is controlled by the key switch, lrte other is controlled by protectthe (Relay E.) rn order ive circuit, the bell to ring, the key switch rust be turned oN and the flow offorprotecii;; ;ir.;it .,r...nt must be interrupted.
Relay B is the protective circuit relay. rt is totrlly tndrprndrnt of the key-switch. The protective circuit ig consiantly energized by the 5 volt battery, and will remain energized as tong as this ,.supcrYisory" current flow is not inG-upi.o. flor of s volt energy throughout the protective circuit is calledThe ,,supervisory,, current because it monitors the status of the circuit.
LJ
slllTcll rERnlHnLt
Fisurr l-S Burglars are not so accomodating a5 to deliberately disconnect the protective circuit batterY ar cut s wire to de-energize protective the circuit relay and causel an alarmr so sone form oi switching (sensor) must be applied to point-o{ potentiar - entry and device wired into the protective circuit- =ach Fig. l-3 shows hon to wire any sensor.
pair is cutl the severed ends are circuit stripped and attached to the terminals o{ the switching device. The device serves as a ,neans ts ra*e or break electrical continuity through the Frotective circuit, as in the example of an ordinary light switch.
One "leg" of the protective
B
( CL08ED
(
)
3ItTCH
( cLoSED
)
e+ OPEH
) 3
EELL CIRCutrT
volts
V Figure l-4
In Fig. 1-4, the closed switch provideg continuity through the proRelay B is held closed by the flow of current from tective circuit. battery. Note that when relay B is closedt the protective circuit relay A remains oPE!n-- therefore the bell cannot ring. B
( oPEx
*
f,+ ( cLoSED
'
SUITCH ( oFEll )
+
) FNOTECTIVE CIRCUIT
BELL CIRC]/IT
y'
3
volts
7 Fi Eurr_.L:5
In Fig. 1-5 the switch (pictured) is open, which de-energizes Relay B, causing it to open. lrlhenever the key-stuitch is turned trN (system operational) and relay B snaps open, relay A will simultaneously snap The only way to disengage the bell is the alarm. closed, activating to turn the key-sfritch to the OFF position' The drop-out action of Relay B is extremely fast , therefore an interruption of current {lot* throuEh the protective circuit need onlY Restoroccur for a fraction cf a second to activate the bell circuit, ing the protective circuit will not release the bell relay clnce it has fatched in,
n[MS:
are The
='._=-,.=I::-::::::I:::-::::::L-_'r_ To present this concept in its simplest fgrm, the protective circuit described in the foregoing section is depicted in a short, straightline configuration, contsining only one siensclr, hlhile there arc ions that call *ar such a short run of wire and just one sensor,situatthey are rare- fn most casesi a protective circuit will be routed through several roclms of a premisesr crn different levels, and will contain absut a dozenr sEparate sensors. Regardless of a protective circuit.s area of cl]verager DF hPw many sensors it contains, the basic principle rernains the samet The protective circuit should alway5 be perceived as a pair of wires with a pohter supply and a number of switches connected in serjes- The open ends of the pair are attached to a pair of scrGlhr terminals in the contrtrl panel, (E & 6. ) In electrical terminology the r*ord serjes neans a continuous string, like a group of people holding hands in a circle. To further this analogyr remember that the words circle and ctrcuit derive clarily fron a common root:
r---+
silTcHEs ,1,
="*-
Eompare Fig. ?-l with the diagram in Fig. 2-2 (next page. ) Study both diagrams and you will find the only difference is that the protective circuit in Fig. 2-Z has four rensctrs wired in series, while the one in Fig. 2-l has only two, and the battery is situated on the other side of the control panel - 0therwise, both diagrams depict exactly the saroe thing I El continuous, serieg circuit, consisting of a single string of wire connecting a nuorUer of cornponents together. Fig. Z-t is a series circuit, so is Fig. Z-?, If this simpte principle is clearly understood, the folloning sections will present no problerns.
Fig. 2-2 is a protective circuitr a control panel; E pair of wires extending out to a battery and four sensors wired in series.
In Fig. 2-l $re see that a "pair" of wires is just a convenient of producing a circle of connected components,
way
COHTNOL
PRHEL
FiEure 2-2.
Fig ?-2 depicts the flow of current from the batteryr through the entire protective circuit (including the relay in the csntrol panel ) , through each of the protective circuit 5,ensors, and back to the battery. This diagram is representative of a such as a row of {sur windows on simple, straightforward installation, the same wall. Ag previsusly mentioned, most installations call for about a dozen protected points, which are situated in different rooms and on more at one than one level of a premises, To begin a protective circuit consecutive to each pair wires of given point and carry a continuctr-rs point nould be doing things the hard Hey. A much easier way to distriburte a protective circuit throughout a premises is shown in Fig. 2-3 (next page. ) (running Study this diagram and you'll find that the "main circuit" of the duplicate exact from the control panel to the batteryl is an protective circuit in Fig. ?-2, with a {ew additions: makes it convenient to The layout of this hypothetical installation of four nindows (sn one row situate the control panel at crne end of a end o{ the wallother wall) and put the battery in a closet at the (trount them. ) sensors'. four This is the "main circuit" and it centains The phantom line of arrt:ws in
A second, separate circuit is started at another premisesf covering five windows and two doors, (seven at them. ) This circuit is tied into the rnain circuit is circuit way aE a sensor would be connected. This "loop" A of the protective circuit.
location of the
sElnsclrs-- count
Ar in the samGl ntrw known as
Another loop is seen at B. Loop E contains only trne sensort (protecting a roof-hatch, cellar door, etc. ), and it is tied into loop A. A third loop, also containing one sensor, is seen tied into the main circuit, at E. Follow the arrows around this circuit (from the battery and back again) and you'tl see that no matter how many loops are addedt and no matter whrrr they are connected, the final e{{ect will be the same. Ag we are dealcomplicated as il. might seem in diagratn formn in principle separate several, intercsnnecting produced by circie-a huge ing'rith (looPs) wires, pairs of 6
+i
the the
1- r-----a-J
a fln
HRn{
one
ive
2-3
CIFCUIT
i---*--+
COHTROL
PRIIEL
'l'
+
:
the BRTTENf
to Figure 2-3. It is important to mention that, technically, it makes no difference the battery is situated in the protective circuit. The hattery ?hele in Fig. ?-S could be removed from its present location and (after the vacated wire ends are spliced together), connected anywhere else-- in the main circuit :r in loops A1 B or e. The protective circuit battery ,nay be wired in a different way and placed inside the control cabinet along with the bell battery, which is sometimes done. However, there is a good rErascrn why this practice should not be followed in sorne situations. For reasons which will be explained in the section on SHORT CIRtrUITS, the protective circuit battery should be situated a good distance away from the control panel and concealed whenever the protective circuit parts are accessible to tarnpering by visitors to the premise!s, customers, ernployees, etc-
EHORT CIRtrUITE r-!-rratlll!lrtlllllllrllltrrlll
ii_ To Bell
-t Protective Circuit
l-
+-+
Jl -J
I
=J Fioure 3-l panel' Hote Fig. s-l shows a protective circuit wired to a control control cabithc inside battery is situated that the protectivr.ircuit protective this of wiring the net, next to the bell battery. ixamine to directly attached is one teraninal of the two-cell battery circuit: terrnbattery vacant G'ne leaving Terminal 5 of the control instrumentn (6) the control instrument' The on terminal, r vacant one and inal these vacant terminals' The to is wired directly protective circuit current from the battery path of the arrows shows that the supervisory (and protective circuit rethe flows through the protective circuit, gituated outside the cabin}'lerE! lay), just as it rrould if the battery manner offers the this in However, wiring a protective circuit et. burglar to knowledgeable a for potential {ar cornprornise, making it easy (short at circuit)t bypass the entire circuit by imposing a "shc'rtr" ssrne point close to the control cabinet' In the giame way that water will always seek the lowest level, electricitywillalwaysseektheshortestpathtofollow:
volts)
.
Fisurr $-2
connected to a Fig. 5-2 depicts a simple circuit, a two-cell battery through current of flow unimpeded larnp by a pair of wires, Note the light' to lamp the entire circuit, causing the to Fig. 3-1) t we see that a short In Fig, 3-3, (which is identical (by attaching a "jumper" wire') pair, has been irnposed across the
I
'-*
._J SHORT
E
To Bell
IF snonr
Protective Circuit
.1
Fiqure 5-5 Note that the current flow has been diverted by the short, returning by the shortest possible path back to the battElry. Electricity flours rith incredible speed, from negative (-) to positive (+) r and will alnays follow the shorte:t porsible rclttr.
il(l
t?
FlEurr 3-4 Fig. 3-4 is identical to Fig. 3-2, with one important exception. short appears at A. Note that the supervisory current ir diverted byA the short bnd returns directly to the battery. Also note (in Fig. S-S) that even though the entire protective circuit has been by-passid, tha protective circuit relay doesn't "know" this. The current still flows through the relayr energizing it, thus the sensors in the protective circuit are unsuFervised.
--l To Bell 6 volt
Protective Circuit-+-
*f t
LJ
ri trl LJ
Fisunr 5-5
Fig. s-5 is identical to Fig. s-1, with one exception. is a properly "supervised" protective circuit, with the battery This situated outside EnE! ouEEiloG! the caDlnet. cabinet. Note Note the effect effect of of imposing imnosino ae short short at at the the ErmE same poInTEs in Fig. 5-3: Thethe flow oi supervisory current is divnrted by the short-- but in this ca:ie the protective circuit relay is deprived
r]f energyr and will drop out, activating the bell circuit. Some shorts are accidental, caused by u;11rn Er damaged insulation But imposing a that causeE; both conductors of a pair to make contact. technique *avorite the is and deliberate short is called "by-passingr" premises was commercial a a{ sophisticated burglars. In one example, An inspection function' t61 failed burglarized and the alarm system circuit ulith the disclosed that the installer had wired the protective public had access to the Because battery inside the control cabinet. had pushed sc,meone hoursr businetss the protective circuit during normal circuit protective the of legs an ordinary straiqht-pin through both out the panel, shorting csntrol pair just a few fiet away from the entire protective circuit. l,lhen the protective To surnmari ze the foregoing in simpler terms: panel and at a remcte control the circuit batterY is situated outside part of the protrctive any out" to "short distance from it, an attempt panel. instantly cause will control the circuit between the battery and an alarrn. battery It is often more convenient to place the protective circuit possibility the when (as and 3-1) in Figshown in the control cabinet u'rong with sf a cornpromise atternpt does not exigt there is nothing power a built-in panel with a control doing it this way. In fact, when an unless "endHowever, alternative. supply is used, there is tittfe method wiring this panel ig usedt tyFe control of-the-line resistor" leaves the protective circuit vulnerable to a gimple by-pass. con#using to The ,.end-of-the-line registor" panel will seem sonewhatprinciple to simple relatively is a it the novice at this stage, but measurpresent a materials conductive understand: All electrically current' able amount o{ specific resjstance to the flow of electrical on the depends (which in measured is "ohms") The amount of resistance For (gauger l wires. of the case in mass, tytre of material and its specific a show will wire ga. cg1PPer of ?2 example, a 2O yard length naturally the level of resistance when measured with a precision meterg yards. 19 than yards more and amount will be legs than 21
The protective circuit relay of an end-of-the-line resistor control panel is sensitive. to an abrupt change in the specific resistance of a overall regigtance trlhen the protective circuit's protective circuiL. resintance specific the o{ sum the include i= measuredl which will panel adcontrol of type this circuit, the levels of every 5ensor in with a very justs to the specific resistance of the protective circuitr guch a5 a bynarrow nargin of tolerance. The slightest fluctuation, out' drop to pass attempt, will cause it o{ the This method is not new, it ig borrowed from the principle by wired are! etc' alarms, bank which r by central statjon connectitrnr station. nonitoring a leased telephone lines to 10
I i
lon
CONTROLE E13---IIIlrEl-I3
Ia5
the
I'lost s{ the components used in burglar alarm systGxn:;, such as bells, rire, batteries and sensors are designed perform to a single, specific function, therefore the only factoi to consider when selecting these items trom the wide variety of available brands is quality. For examPle' a bell is a bell and is expected nothing rnore than make a noise' There are many bells avaitable toondtl the -sarne market, most of *tich are veFy well rnad€ and priced within the equipment rf a bell bears the u'L' label and is sold by a regular alarm rangE!. equipment dealer, this is adequate assurance of reliable quality. The same can be said for wire, batteries, supplies and sen_ srtrs' from the simplest sr*itch to the po'er most sophisticated detector' HoweveFt the same cannst be said for control panels rnotion because there simply arE! too many different brands and models available, sor€l af which provide numerous atrcessctry functions in addition to the prirnry function of activating a signal when the protective circuit is disturbed. The control panel described in this is known in the burglar alarm trade as the "1oo control" end it rnaterial has been the standard of the industry for tnany yeaFs- The 1oo control consists of a plain, sturdy enclosure, (cabinet), with a t'lodel loo control instrument the inside and a two-position ON./EFF switch shotring on themounted on outside, nothing mEre. In spite of the many high-tech alternatives available the market, the loo is preselntly in us. in millions of commercial on and residential installations' These panels ere preferred by many comrnrrcial alarm contractors for use in leased alarm systems, which is ni{icant testimanial because leased burglar alarrns are profitable a sigpnly i{ they are trouble-free and the equiprnent is cost-efficient. The loo is an inexpensive, reliable alarm control which may be expanded upon by adding any number of burglar optional accessories such as a Permanent power supply ("power pack"), entry./exit delay tim€lrr bell cuto++ timer, AC switching relay, and rricrre. These actressclry modules arE! quite easy to add to a basic contrsl panel at any time after the system is installed and operational. The alternative to using separate modis to purchase a control panel with all of the lles accessories buitt in' hthile this is a suitable alternative for desired the experienced installer, a novicE is likely to find a sophisticated, multi-function control panel to be baffting. This is why the forrnat of this material is structured around a sirnple, basic control panel, which the novice installer is well advised to start out with.
Listed below arE! a number of useful accessory control features. r+ preferred, there are many control panels avaiiable that o#fer any combination of these features, and mor..r ES buirt-in options. 1l
PtlhlER PAtrKSr
temporA popular alternative to operating a burgtar alarm syst€ltnactn perrarrent called transfortnerr Atr-dependent ary batteries is to use an po{rer supplyr BF pa{ter pack- But a FElrmanent power supply should nevFr stand-bv- -battery to it be used without attaching a trickle-charging, failure deliberatet Frefor maintaining power in the event of an AE outsideor the premises' from wiring house the burglary tamp=iittg with TO 11O
t i ol'r
non
BELL
H
r
3t
--....-..,'..'.--..---=
Bell Circuit lr L TO 110 AC
I
c
I
2
3
4
I
AC
qui f .h
E
- L-? rr Protective Circuit
6
5
J
E
D
tttl-r-
tt2 tT1 IsIa rla
B
A
Power Receptacle
Fiourc 5-1. Fig. S-l shows the layout of a l'todel loCI control instrumentr nired up witt " number trf accessc1ry control-{unction modules' A is the power supply Hith a stand-by storage battery attached at B. ACt Terminals I & ? of the power pack are cclnnected (trt toa 11O plug-in via (using lEl 16 gauge wire), Pr either directly, with the unit when purchased' ) included be will twnlcn transform€lr, 3 & 4 of Terminals 5 & 4 of the power supply are wired to Terminals {or energy the control panel, providing a permanent source of 6 volt in shown These p61wer pack terminals replace the bell battery the bell. previous diagrams. of 5 Terminals 5 &.6 of the power pack provide a pernanent source manner and are wired in the sam€r volt energy for the protective'circuit pack terminals replace thc propower These 5-1. Fig, in as described tective circuit battery shown in previclus diagratns. ETAND-BY BATTERYT
pack are wired to the stand-by batteryt TerminalsT&Bof the power thl power pack will simultaneougly switch (8. ) I+ the Atr Power Iiii=, to battery suPPort- Eecause the standby battery is under continuous 12
charger it retnains Perlnanently energized tE peak capacity and does require periodic replacement. ENTRY/EXIT DELAY
not
TIFTERc
The itern shown at D repres;ents an entry/exit delay timer module. Note that it is wired directly into the protective circuit. This device has two separate timing circuits, (ENTRY and EXIT), both of which are adjustable to provide a delay period #rom O to 6O seconds. The EXIT delay enables the user to switch the system 51n and leave the premiseg without activating the alarm. Likewise, the ENTRy delay provides sufficient time to re-enter and switch the systern off before the alarm activates. An ENTRy delay timer should always be adjusted to the shortest possible delay period, for obvious rGE: An excessive pre-activation delay might afford a burglar sufficient time to locate and forcibly disable the control panel before the system activates.
TIFIED BELL trUT-OFFr
F represents a timed bell cut-s{f device, which ig wired into the bell circuit. This device automatically cuts otl power to the bell after it has rung for a pre-selected time. Twenty to thirty rninutes is plenty of time for a burglar alarm to sound, whether the cause is an entry attempt trr a malfunction. (l'lany localities have ordinances that randate a 20 - 30 minute maximum ring-off period for burglar alarms.) ffi EI{ITtrHINB RELAYT H is an AC switching relay. It is connected (g) in parallel to the bell circuit pair. lchen the alarm is activated, thr rtml currrnt thrt rings thr ball rlto Enargizrr thir rulry, causing its high-vottage rated contacts to close. These contacts are wired directly to ttre terminals of a light-switch. Elosure of this relay's contacts will thug turn on whatever lights the switch normally controls, which might be a single table-lamp or a string o{ exterior floodlights. The cornbined effect of a loud bell or siren, (or both), and bright liqht will usually drive off the most brazen burglar. Note that the AC switching relay is connbcted to the bell circuit wiring between the control panel terminals and the bell cut-off device at F- I+ it were connected anywhere beyond the bell cut-off, it would be de-energized along with the belf wtrEri ttre tirrer's contactg opened. This would turn off the lights, too, which is not desirable. ].IULTIPLE
ZONEST
It is often desirable to wire nore than one protective circuit into the same burglar alarm system. The reason for doing this is to divide the system into separate ,,zonesr,' each of which may be temporarily l3
,,shunted" (removed, or "by-passed") from the system without affecting valuable in situations where a the remaining Zot'|rS, This capabilityis isdiscovered prior to closing the problem in a protective circuit day' hlith a single following the premises and cannot be serviced until be switched offt systern entire the zone system this would require that leaving the prernises totally unprotected' is that of inconA trick which is used successfully by rnany burglars on protective of strip a spicuously passing a raaor blade through during normal busine:r's{oiI houret the interior glasi of a business premiges protective circuit will knowing that ifri= inconspicuclus damage to the the premises or leave it in force the owner to either remain overnight unsusPecting shoptiredr a of unprotected, which is usually the choicehours {or a serviceman' telper who doesn't want to wait several + Control
Bell /ci".uit
Panel
Protective Circuit #l I
I
6 Yolt 8el1 BatterY
Protective Circuit
#2
Flqura 5-2. to counter this The use of a two-zone control panel in a good way Note the system' two-zone a of Fig. 5-? depicts the layout trick. single-zonG! previoust in seerr thos€! and differences betneen this layout circuit Prottctlvr diagrams: This control insirument has a gcond (7 & strip' connecting the on relay (E) and anothrr peir of terminalr protective circuit' Everything g) which accornodates the additional else is the 58fl1E. Assume that protective Circuit *1 is dedicated exclusively to supclrwhile Protective vising the premises nindow {oil and nothing else,used in the system-sensoFs remaining the circuit l]2 is dedicated to exist possibilities Several device: which includes a nbtlon drtrctor sabotage who burglar(s) the is possibility in such an arrangement. One has been disahled' the foil pattern, believing that the entirF sysl:m(unknown to them) which back-door]etc., a will attempt to break in via (zone 2' ) is protected by a sGlnsctr in Protective trircuit ll2, and enter Another possibility is that the burglar(s) will break of the because unprotected lefi is right through a glas5 pane, which enter the energized they'is witlwired disabled zone. Bnce inside, howeverrinto the active inicn detect;;'Oeviie, motion field of the (Zone 2. ) circuit, 14
The third possibility expresscrs the principle of xhe day/night control techniquer3 The day.hight control is a two-zone system which ig used in the tnanner explained above: Zone one'is dedicated to nindow foilt skylight lacing, wall foil and any other sensor nhich is not subject to operation or disturbance by routine daily movement. All of the other sensorsr door and nindow swii,ches, motion detectors, etc., those devices which are constantty being operated or othenrise disturbed by routine movement, are wired into Zone Two. During nctrmal business hours the alarm system is left switched on, but zone Two is shunted- (l"lultiple zone panels have gwitchindividual es to shunt any zone- ) Door and window may then be freely operated, and motion detectors disturbedswitches nithout -.iivating the alaror, because their circuit (zone) has been shunted out. But the that any-TffiE- o+ damage occurs in Zone one, (tike a deliberate instant in a foil pattern, broken lacing, etc.), the alarm will activate.slit This enables the premises; owner to iarr for service immediately sibly observe the cause of damage the moment it happene. and to pos"DAY/NrGHT" control panels are conmonly used for conmercial premises rhich are freery visited by the generar public. it"=, are gimpry a 'two-zone box" with a switching frovision'that impcrr-rily the bell circuit to a buzzer and right'on the face of thl control shifts inet' this is a convenient altirnative to having loud bells panel caband sirens go off if Zone one is activated during business iours. hlhen Zone Two is restored prior to closing, the norial bell circuit is re-engaged. Eontrol panels are available with built-in provisions for two, fotrr or six separate zonesr crr more. The use of multiple zones, particularly in systems that utilize multiple provides a valuable rdvantage in terms of ,,trouble-shootingr,, loops, which is locettng the cause of a protective circuit problem: Refeiring to the foregoing example of a two-zone systern, a break in a foil p"fter' wourd immediately lrolrtr the problem to Zone One. suppose that a burglar alarn system a dozen separate loops, covering three different levels (floors)utilizes prenrisElsr o{ a r+ all twelve loops are tied into the same protective circuit, problern a in any individual loop will require trouble-shooting the entire twelve loop protective circuit. And if the problem is discovered rrhen the system is switched on just prior- to securing the premi=ri, (which is usually the case), when it is not csnvenienf to troubte-shoot and repair it, the entire system must be disabled overnight.
If a multiple-zone control panel is uged in tha sane gituation, and the system is divioio into four, (or more), zones, the zone in rhich the problem exists will be immediateiyseparate identiiiro by an indicator lamp when the system is switched on. rf the specific cause the problemt (a malfunctioning or damaged sensor, broken wire, etc. ) of j cannot ue tl: indicaii"s-io",--;;t'be out by *1.:::"-t:::::o_::l_:=p:1i"9, aoving a panel switch, leaving the remainder o{ the iystenrhunted operational. The cost of a multiple-zone panel is greater that of a basic, singlEt-zone model and there is much more work than involved in running a nunber of separate protective circuits directly tE thrc control panel, t5
instead of just one. But in view of the foreqoing advantages it makes sense to go the extra mile, The advantages o{ a multiplE!-zone =ystem are obvious and well worth the extra effort in the long run. In comparison with the simple, straightforward design and aFpearance control panel r a multiple-zonet multiof a basic, single-circuit feature control panel might he an intimidating Prospect for a beginner. It should be kept in mind, however, that regardless of how many separate zones a given control panel r*ill accomodate, the basic principles outlined in this material will apply to each of them. control panels available from different the various manufacturers it would be irnpractical to attempt a description of each of thern in one book, because by the time this book is published there undoubtedly would be morEr. (Few of which will of{er any really useful n new features. ) of the accessory functions There is no question that some (or atl) described above are necessary for certain situationsr but a good rule to follow r'rhen selecting a control panel is to avoid those which seem to promote gadgetry as opposed to sensible technology and are not truly buzzers, whistles and While seductive lights, useful or practical, purpose luxury automobilest such in bells serve an actreptably frivolous more confusing are o{ten alarm control redundant {eatures in a burglar than convenient. A listing of price averages for burglar alarm equipment is found at the end of this book. The prices given are the typical retail cost of professional-grade equipment. The reader whs plans to reliable, install more than a few burglar alarms will savE considerably when purbut the beginchasing equipment directly from a wholesale distributort patroniz€r retailer who is not an experienced ner is well advised to questitrns. opposed to answering basic, "stupid" Due to the I arge nurnber of
blholesale distributors discount up to 4O7. oft retail and thus depend patience on brisk, high-volume sales, which is r{hy they have little go?" A wires custsmers. the and where do with "girnme one of those quantity orders from busy with large wholesaler's counter is usually working installers who know exactly what they needr and how many dozent so the novice who's looking to save a few percent on the cost of a trontrol panel stands an excellent chance of having a "white elephant" unloaded on him by a wholesaler who's been looking for an inexperienced amateur to dump iL on.
alright for a beginner to buy a control panel with a few, nece5sery control features built in, provided the dealer is willing to explain the various wiring connections and any special requirenents at the time of sale-- tnd provide additional information afterwardt i{ needed. After the first installation has been completedl the novice experience to evaluate the more sophigticated will have sufficient panels. the simpler the betterthenq Until control It
is
t6
BELLB & SIRENE
E=E=-==-='=--E3E-E==-=E
E
Because a burglar alarm bell will be perrnanently to a variety of weather extremesr one should not consider usingexposed e bell which is not "UL Listedr" meaning that its overall quality has been tested and found acceptable by the Underruriters' Laboratories. (The UL label is a generally reliable indication of quality where alarrn components are concerned' ) A burglar alarm bell should be contained in a heavy-gaugErr weather-resigtant , louvred cabinet, which be equipp.i with tamper-detecting sr"litchesr crF',tamper switches. should .,
The inset above shows a burglar alarm bell in a heavy-duty cabinet. Note that the gong is mounted on a removable plate, (called sion plate. ) The plate isolates the gong from the mountinga 5uspElnsurface rhich otherwise lrould absorb' the g-ng's reEiclnance. The iuspension plate is secured to internal brackets by machine screws, then the outer door is sealed by more screws. Renoving fine-threaded machine 5crews is a time-consuming Procedure which, in combination with the measurels outlined below, provide an adequate level of protection for the mounted bell. Even when a bell cabinet is msunted high above street level, sotn€! burglars won't hesitate to climb a ladder to get at it, provided they can do so withsut being seen. The following descrihes how a properly rrired bell will frustrate such a conprclmise attempt: Fig' 5-l {next page) shows a bell cabinet with the suspension and gong rernoved- Note the two tamper switches rnounted on the plate side of the cabinet, r*ith their plungers facing to the front and toinner the back' The ptunger of the front swititr protrudes through a hole in the suspension plate, (when it is in place), and the ptunger the rear switch protrudes through a hole in the back of the cabinet.of hlhen the cabinet is mounted'and sealed, the plungers of both switches are Ecrmpressed by both the mounting surface and the closed cabinet doorFig. 5-? is a close-uP view of the tamper switches (only) and how they are wired- (The three holes cln each switch are for the mounting. screws. ) Note that a short, ZZ gauge iurper wire (A) extends from a screw terminal of one switch to a terminal of the other switch, conjgining both snitches . series connection. B is a ZZ gauge pair, which is brought into Fy the premises and connected to any rooi oi the protective circuit17
Figurc 5-2
Figurc 5-t
(I+ convenient, this connection ,nay be made inside the control panel.) In effect, these switches represent a separate loop in the protective circuit and they serve the same purposel as any of the switches used inside the premiseg to protect windows and doorst etc. Fig. 5-3 is a side-view of a bell Even if a cabinet, mounted and sealed. burglar removed the three screws that seal the cover, the moment the cover is opened the plunger of the front switch and will release, opening the circuit The burglar still activating the bell. would not be able to reach the bell wirremovi ng three more i ng r+i thout f i rgt screns that secure the suspension plate. Not an easy task while standing cln a ladder with a 1OB decibel bell pounding artray in onEl's facet wondering i+ the politre are on the way.
I
l,
Likewise, i+ the cabi net the activated will be surface, the bell For this rear tamper. enough to release the pos=ible. be mounted as secunely as Flsurr 5-5
an attempt is made to pry ar{ay f rom i ts mounti ng moment the cabinet is pried reas;on, the cabinet should
to the traditional burglar alarm tone is similar in its oscillating which siren, bell is the electronic vehicleg. police ernergency cars and other in to the sirens used An increasingly popular alternative
sirens uged {or burglar alarms consist o{ a PA speakprotective cabinet, much like that of a bell cabinet' in a er contained siren is used in place of a bell, it is recommended electronic I+ an that a 12 volt model be used because of the relatively weak noise level of the 6 volt versions. The electronic
)}
t8
A typicat electronic siren speaker is shown above. The cabinet on the right is tamper-protected in the seme manner as a bell cahinet. l"tost of these siren= employ a remote driver/amplif ierr a :ieparate nodule which is contained in the control panel. The nrodule is wired to the bell terminals o# the control instrument, and the nires leading ttr the siren are connected to the module- (Some control panels have builtin siren drivers. ) l.tost siren drivers can acccrmodate up to f our separ(An tnnuncittorl. ate speakers, which enables the use of multipll "annunciator" is any type of noisemaker, a bell or a siren.) Bne technique which will greatly enhance the overall effect o{ e burglar alarm is to use an electronic siren inside the premisclsr in addition to the exterior beII or siren. The noise generated by an indoor siren is deafening and will deprive a burglar of the ability to listen for approaching danger. A convenient way to do this is by wiring a siren driver directly to any type of indoor FA speaker:ir or to a pair of existing stereo sPeakersAnother useful actressory ig a strobe. The effect of a strobe burst in a darkened area is virtually blinding, causing general disorientation and loss of balance. For outdoor application, weatherproof strobes are available for mounting directly onto betl or siren cabinets. Thege are powered by the bell circuit and serve as a beacon for responding pol i ce,
Thus far it has been shown how adding modular accclssories to a basic burglar alarm control can ring a bell outside and a siren insidet
temporarily blind a burglar with switch on outdoor or indoor lightingn guide responding police to the sound o{ an a strobe burst, 'visually active alarm arrnunciator, and automatically silence the annunciator(s) after a fixed period of time. The following sectictns are devoted to the many seng,ors, {detectors and switches}, which may bc wired into the It is assumed protective circuit to initiate the foregoing effects. of a operation acquainted nith the that the reader is sufficiently functions control of burglar alarm system that no further digcussion If not, a review of the foregoing sections is will be r=.===..y, recorotnended before Proceeding further. 19
I TESTINE IIITH A IIETER
Working with burglar alarms calls {or the performance of certain tests to determine the factors of polarityt continuity and voltage. Fortunatelyr these tests are quite simple and each nay be performed with an Elasy-to-use instrument called a ruftireter, or "meter" in the language of the trade.
There are hundreds of differe'nt types of multimeters availahle; ranging in price {rom twenty dollars to several hundred dollars. The more expensive rnodels are extremely accurate and are designed for sophisti(Such precision is not required for testing burgcated aPPlications. lar alarm circuits. ) Small r lightweight multimeters, which are ideal {or burglar alarm r+orkr are available from alarm equipment suppliers for around thirty or forty dollars.
Because of its highly technical appearance, e multirneter can be intimidating to the novice who has never used Eror. The face of the meter is graduated into hundreds of fine incrementg and there are many numbered settings to select from. However, the device ig extremely simple to use: A typical multi-meter is a rectangular device, with a pair of wire probes extending frorn its body. It rnay be set to test either Atr or DC
voltage or electrical continuity through a "dead" conductor. Fecause burglar alarros operate on DC, the only Atr test will be that of determining whether a wall receptacle is live prior to plugging in a polrer supply transforrner. This is done by selecting the AC funetion and inserting the probe tips into the receptacle. I+ the meter moveg, the outlet ig live. If it doesn't arsve, the sutlet is dead. Aside from thist the meter will be used exclusively {or DC and continuity testing: POLARITY:
Polarity means the difference between the Positive (+) and the Negative (-) "sides" of a DC power source. It is important to knon which is which because Dtr components require that polarity be observed during wiringr that is + ttr +t - to -. The terninals of most cclrnponents are clearly marked with a + or symbol r trF by color. Red is Positiver black is Negative. Connecting a component the rtrong way (cross-poIar izingl., will cause damage, malfunction or non-{unction. It is simple to deterrnine the polarity of a Dtr powrr source! The probe wires of a multimeter are color-coded red and black. These probes are applied to the terminals of the power scturce, (such as those of an unmarked battery Elr transf orrnEtr, ) If the needle of the meter swings to the right, (which is the normal direction), the terminal to which the RED probe is applied is the POSITIVE side. If the needle moves backwardr this roeans the RED probe is applied to the NEEATIVE 20
side. A simple way to acquaint oneself with this test is to alternately apply the probes of a multimeter to the terminals of any type of battery and note the direction in which the needle rntlves. Froper polarity must be observed when connecting the ends of a protective circuit to the terminalg of a control panelImagine that the protective circuit battery is located a considerable distance away from the ctrntrol panel to which you are about to connect the protective circuit pair. The polarity of the pair rnay be determined instantly by aPplying the meter's probes to the wire ends. If the needle snings to the rightr then the conductor to which the RED probe is applied is PCISITIVE. I+ the needle moves backward, the RED probe is applied to the (The control panel tenminals will always be markNEGATIVE conductor. edr either with the + and - symbolg or the colors red and black. ) CONTINUITY!
Eontinuity means the ability of a conductor, (a wire, etc, ), to accomodate the flow of an electrical current. To perform this test, the meter is set to the position marked OHHS, (meaning resistance,)
Probcs Touching
Fieuru 6-l hlhen the meter's probes are brought together the needlc will sning all the way to the rightr indicating unimpeded continuity. By bringing the probes together a circuit is completed, consisting of the probe wirest the neter's battery, and an electromagnetic coil inside the rnetelr that rocrves the needle. U the metet'= ptoUts are applied to any conductive rnediun, whether protective circuit, the shaft of a screwdriver or a I'OOO ft. the effect will be the same. So long as there is unbroken continuity throughout the conductor, the needle will indicate by swinging to the right. l+ the conductor.
needle doesn't
movc!, there 21
is
a break somewhere in thei
(INTAcT)
Circuit is intact - leter needle deflects to right
Flgurr 6-2 Fig. 6-2 shows a probes of a meter, conductor is intact, uity, (no resistance
conductor, (a pair o# wires open at one elnd.) The (A & B), are applied to the open ends. Because the (no breaks),' the aeter is indicating full continto the flow o{ electrical energy, )
(oPrN)
Circuit is broken (at arror) ileter needle does not
rove
Flgure 6-3 In Fig. &-3 there ig a break (open) in the lower leg of the conductor. Note that the needle hasn't moved frorn its extreme left positionr showing that energy cannot flow through the circuit. I
;
Breakg in continuity are rarely visible. One example of a situation in which a concealed break would be impossible to locatc nithout the aid o{ a meter is an clpcln occurring beneath the insulation of a conductor. This can be the result of a manufacturing defect, excessive strain when pulling wire through a tight space or careless use of a staple-gun while fastening the pair. The example seen in Fig. 6-s shows such a breakt it could be precisely located by advancing the probes of the meter along the length of the conductor a few feet at a time. trontact with the wire under the insulation is nade hy pushing map pins through the insulation and applying the neter probes to the pins. Ideallyt the tips o# the meter's probes will be alligator clipr into which pins may be clamped.
Burglar alarm wire is usually packaged on 5OO' spools. The wire is wound on the'spool so that both ends of the 5OO' pair are exptrsed and accessible' By twisting the open conductors at one end of the spool together and applying a areter's probes to the other endg, the entire 5OO'pair may be tested for a defect while stitl on the spool. It is reccttnmended that this test be performed on every spool of wlrc prior to using it. Each spool is factory tested right after it's wound, but damage could occur during shippingIt is rare that a broken conductor will be {ound in a fresh spool of wire but, i+ one exists, it's best to find it before the wire is installed-- especialty inside a wall ! 22
EENSORS
Ey now it should be clear that a burglar alarm is activated by sone action which causes an op€rr (break) to occur at rny point in the protective circuit. The open may be produced by disconnecting an external protective circuit battery, rernoving either o{ the protective circuit connectisns from Terminals 5 & 6 of the control panel r cutting a conductor or otherwine producing an opGn rnywhcrt elong thr lcngth of thr protective circuit wiring. As explained in the secticrn on PRETECTIVE CIRtrUITS, a wide variety of special devices ere situated at strategic locations within a Frotected premises and wired into the protective circuit. This variety of devices ranges from simple mechanical switches and {ragile conductors ("lacing" wire and windsw "foil") to sophisticated electronic nrotion detectorg such as passive infra-red, photoelectric, micro-wave, ultrasonic, capacitance and audio-discriminator devicets. Regardless of how simple sr complicated any of these devices might be they all serve the same Furposet that of producing an open in the protective circuit when disturbed by movementr oF excifed by the prennce o{ something apprclximate to a human form.
Any device that is wired into a protective circuit to detect movrnent or prasence when it is operated (as in the case of a switch) or cxcitedr (as in the cage o{ a motion detector}, is called a sensor. All sensoFs are connected into the protective circuit in the same mannerf by cutting one leg of the protective circuit wiring, stripping the severed ends and attaching thern to a pair of screw terminals on the devi ce.
The novice installer should not be intimidated by the complex nature of any type of motion detectsr apparatus. Like radios and tv sets, one needn't know what makes them tick in order to use them efficiently. All that the installer needs to know about an individual detector is its operational nature, its capabilities and limitationsr how to apply it and test it for proper operation. These procedures are covered in the following segments.
It is neither necessary nor practical for the installer to repair a motion detector device in the f ield, or othernise. I'lhen it is determined that a detector is malfunctioning, the accepted practice is to remove it and retul'n it to the supplier for repair. The malfunctioning device is then replaced with another of the same type. l+ a r€!placement is not immediately available, the wire ends from which the device is rernov€rd are spliced together to restore the circuit until the device is returned. Excluding a detector from a protective circuit, even for one day, is not a desirable practice, Professional installers avoid this by making sure they have an adequate gtock of replacement coroponents sn hand. ?3
PLUNGER ShIITCH
a plunger switch is no different from the springtrperationally, loaded button used to ring a doorbell, Pressing the button cltrsErs a pair of internal contacts, completing a circuit, sausing the bell to ring. lJhen pressure is releasedr the contacts release.
I I
et unlq
Compressed
r.
Extended
Fis. 8-2
Flc. E-l
The major difference between a plunger switch and a doorbell button Ag seen in Fig. B-lt the pushis shape and internal construction.
button is a plunger that protrudes about 3/4" from the {ace (C} of the switch. A relaxed spring is seen inside the body of the switch forcing the plunger outwardr leaving the contacts clpen at B. Fig. E-2 shows the plunger compressed into the body of the switcht collapsing the spring, causing a U-shapedl bronze jumper strip (D) to complete a circuit across the internal contacts. A pair of Ecrer{ terminals at A are seen as physical extensions of the internal contacts, (B). The reader who is experienced in electrical wiring will probably consider the foreloing description of a sirnple device to be somewhat tiresome, but this exhaustive explanation will be helpful to the novice in understanding how switches work and how they are used in a protective circuit. So long as pressure is maintained against the plunger of this switch the jumper strip remaing compressed against the contactst providing electrical continuity through the switch via the externrl terminals. lrrlhen pressurc! is relaxed the jumper strip withdrawsr producing an open This will activate the alarrn. in the protective circuit. 24 i
Although a Flunger switch is one of the simplest and least expensive of all sensors, there are many ways to use it. Fig. B-3 shows the rnost cr:tntncln application: The ptunger switch is mounted in a 3/4" hole bored into a door-#rame- The edge of the door will ctrrnpress the plunklhen the ger when the door is closed. door is opened the plunger will release' A pair of wires is seen attached to the terminals of the switch and drawn through a small hole drilled through a baseboard. This pair will be connected into the protective circuit at the closest junction. This wiring route Presumes an exposed wiring job. I+ concealed wiring is pre{erred, (which is optional } t the wlring may be snaked through the wall or tucked behind the baseboard.
iF 1l 1l
tt
li rl{
.jr
Fiq. E-$
Another way to use a plunger snitch is to mount it in the bottom channel of a double-hung window frane (and another in the top channel t i+ desired) and snake the wiring through the wall. t{hile this technique provides absolute concealment, a special r weatherproof Plunger switch must be used because of the direct exposure to moisture. The rubber boot and the weatherproof plunger is enclosed in a flexible houging of the switch is moigture-resistantThese are just two of ,nany possible applications of this versatile inaginare limited only by the installer's switch, other possibilities of surface in the ation: For example, a plunger switch may be mounted of a valuthe weight a table or cabinet and the plunger cotnpressed by able itern of property. Removal of the item will release the plunger. This type of application is called a "trap" and is useful to ensurEr that an alarrn will be activated even i+ a burglar toanages to bypass the periseter sensors and gets ingide. Such a "trap" may be rigged and wired into the active "zone" of a dayfnigh* syster to guard against renoval o+ certain items from a premises during nornal business hours. The "tamper" slritch described in the section on BELLS & SIRENE is simply a plunger switch that is speci{icatly designed for surface mounting inside a bell or siren cabinet. This type o{ plunger switch may al=o Ue rnounted on the sill of tn outward-opening casement window so the sash of the windon will compress the plunger when the window is cl osed.
?5
FIABNETIC 8I{ITCH t3-=E=E=E:EIEE--3I-t!aIt---!rEt-I-rItEC
A rnagnetic switch consists of two separate parts, the rwitch and the magnet. Except for a pair of strrew terminals on the switch, both parts are physically identical. one part is a short rod of permanent magnet sealed in a plastic enclclsure. The other part containr a clever rwitching mechanism.
Inside the switch housing are a pair of contact EFms. one arm is stationary, the other is pivotal. The pivoting contact apart from the stationary contact by the light pulling +orce isof held a tiny, bronze', coil spring. The arm of the pivoting contict is made of ferFous metal t which is receptive to magnetic influencer. gJhen magnet is brought into close Froximity with the switsh, its force the outweighs that of the coil spring and the pivoting arm is drawn sharply into contact with the stationary arrn. The screw terrninalg on the switch housing are extensions internal contact arms. lrlhen the two arrns are drarn together ofby the the magnet's influencErr continuity is established between the rtrre$, terminals. lrlhen the dominating magnet is withdrawn, force of the coil spring is restored and the pivoting contact is the putled away from the stationary contact. The operation of 'a rnagnetic switch may be observed by applying the probes of a rneter, (set to read continuity), to the screw terminals of the switch tt9 observing the behavior of the needle: (See 9-1, next Page. ) t{hen the switch is separated from the magnet , Fig. li/4^ or more) t its internal contacts remain oFen and there is no continuity, thus the needle will not move. When the magnet is brought ctose to the st*itch its internal contacts snap together ind the needfe swint- itr..ply to the ri9ht, indicating continuity betneen the screw terminals, 26
Sritch llagnet
*
*
f]]]-
Sritch
raonet
Fiq.9-l Because of its clever, tno-part design, the magnetic switch is compatible with a wide variety of applications, the most typical of which are depicted in Fig. 9-2, below,
Flg. 9-2 In Fig. 9-2, a series of five nagnetic switches are seen applied to a door and two windows. The switches are shown as Ar the magnets are B. The door switch is mounted on the door frame immediately over the upp€lr edge of the door. A magnet is mounted on the door directly beneath the switchr holding the internal contacts closed and maintaining continuity through the switch. The windons represented in this diagran are the standard, doubleThe switches art mounted on the window frarnes, the magnets are mctunted on the sashes. ltlith the window switches and magnets arranged as shownr normal novement of the upper and lower sashes is unobstructed. hung type.
The magnetic switch described above is the surface-mcrunted type. It may be fastened to either a wood or metal surface with a pair o,J t/2" (*6) screws. The ideal spacing between magnet and switch ig L/8". l{hen the mounting surfaces for the magnet and switch are offset, making it dif{icult to align the two segments, plastic spacers (and specially designed brackets) are available to cornpensate for the offset distanceThe plagtic spacers, (or "shims"), are l/8" thick and conform to the mounting base shape of the magnet or switch- lrlhenever a rnagnetic switch is used crn a ferrous metal surfacer at least two spacers should be used to move the magnet and switch farther away from the mounting 27
sur+atre. otherwise
the metarlic
,nass will
magnet and weaken its ef{ect on the switch.
absorb energy
from the
Dther types of magnetic switches are available for special applications. The shape and construction of these devices are dif{erent but the same operating principle applies to each of them.
€< /,
Item I is a sealed, cylindrical magnetic switch, which is L/4r, rlide X l-l/?" long. Instead of Ecrew terminals for connecting it into a protective circuit, a pair of wire tajJs is provided for soldering to the protective circuit wiring. ? is a bare (not sealed in plastic) rod of permanent magnet, which is the same size as the switch. S is a plastic mounting tab, curled at one end into a loop which accomodates the magnet or switch perfectly. On the back of tire tab is an adhesivec pad for convenient, stick-on mounting. This type of switch is commonly used on horizontal sliding, aluminum-frame windows, (on which the rectangular type described above cannot be used because of their shape and size.) A cylindrical switch and a magnet are slipped into separate mounting tabs- The switch is gtuck to the frarne above or alongside the sliding window- A magnet is stuck to the edge of the window glass in alignment with the switch, The mounting surfaces should cleaned with alochol be{ore applying the tabs or the adhesive is be likely to fail. This type of magnetic switch is alscl appropriate for concealed atrplications. One common example is that of boring l/4', hole up through a doot--fratne, and another l/4" hole down l-t/Z" a into the upper edge of the door. Both holes nust be carefully aligned. The switch is fitted into the hote in the frarne, with the wire tails extending upward into the hollow above the frame for connection to the protective'circuit. The magne't is f itted into the hole in the door edge. lrlhen the door is closed the magnet is aligned end-to-end with the switch. The foregoing arrangement also applies to wood-frame, double-hung windohrs, (both top & bottom), when a totally concealed installation is desirable. A large, heavy-duty magnetic snitch set, both parts encased in cast available for protecting rotl-up garage and warehouse doors. This switch has a long pair of connectirrg *irei extending from one endt protected.within a 24" length of f lexibl;, l/4,' alumir,,rn t,.,bing. The switch may be surface-mounted or set in poured concrete on the floor just inside the door and alongside the frame, where the tube is bent around the frame and upward along the inner wall. The wire tails are connected into the protective circuit. The magnet is attached to the lower edge of the door immediately above the switch. lrlhen the door is rolled down, the magnet engages the switch. This type of switch should not be used on -roll:tp doors which are loosely hung and subject to movE6Ent, (from wind, vibration, uumping, .t.. I aluminutnr is
28
LEAF SI{ITCH
The feaf switch is named for the flexible strip (leaf spring) that extends frorn one side, This device ig operationally similar to the plunger switch. It is equally inexpengive and very simple to use.
The major difference between the leaf and the plunger switches is that the leaf switch is surface mounted. Note that there are two pairs o* mounting holes on the body which enable the (1" / *6, mounting screws to be inserted either from the top or side of the device. Connection to the protective circuit is made via the pair of scFeht terminals seen on the front side of the device. The leaf switch is a quick, handy, inexpensive way to protect any type of opening which is covered by a movable barrier, such rs a roof hatcht trap-doorr etc. The device is mounted cloge to the barrier so that the lea{ is compressed hy the barrier when it is closed. Eompression o{ the leaf engagesi a pair of internal contactg. Relaxing pressure against the leaf separates the internal contacts, triggering the r alarm.
29
I.IERCURY 6T{ITCH
The principle of a mercury switch is expressed in the above diagramr Seen on the left is a laboratory +lask which is partially filled with merrcuryr a highly conductive, heavy liquid substance. Two rigid wires are Passed through the cork in the flask and extend donnward into the mercury. The probes of a meter (set to read continuity) are attached to the external ends of the two wires, indicating that the rnercury is conducting an electrical current between the two wires. On-6e rffght the flask is shown tilted to one sidel withdrawing one of the wires from the conductive ncrrcury. As indicated by the zero continuity reading cln the meter {ace, the effect is identical to opening the contacts of a switch. The portion of the wires inside the flask are regarded as internal contactst the tips of the wires extending outside through the cork are the exterior tertinajs. Thus there is no functional di{ference between this ingenious device and any other switch. I'techanically, the mercury switch is operated by simply tilting it.
l'tercury switches come in many shapes and sizes and are used in a wide variety of apFlications, such as sxitching on the light in an automobile trunk nhen the hatch is raised. Regardless of the shape of its housingt inside every rnercury switch is a sealed glass vessel with a pair of contacts and a pair of terminals arranged egsentially the Eiame as in the flask exaople seen above. In order to adjust the sensjtirityr or angle of activation of a otercury switch, the vessel itself is suspended cln some type of mounting bracket. The type of mercury switch used in burglar alarms is represented belowr
A is the mounting bracket.
SCreul.
Bis the switch. 30
Cis
the adjustment
the bracket is fastthe mounting surface, the probes of a meter are attached to the terminals of the The angle of the switch. switch is then adjusted to partilt the vessel. The tially objective is to cause activation when the mounting surfacc two or three inches is tilted in its opening direction. After
ened to
A mercury srlitch may be uged to monitor a hinged skylight cover, transom, cellar doort trap doorsr ctF whatever application calls for this type of sensclr. A special-purpose door cord (C) is available with a flexible connecting cable and a terminal block attachedl for applications like the one seen on the left:
This version enables the attachment of a foil pattern to the terminals of the switch (A) which is mounted crn a transotn. The terminal block (B) ig fastened to the adjoining frame. cablet (called a The flexible door cordl I enables free ncrvement of the transom when the alarm is not in use. hlhen the alarm is switehed oftr disturbance of the foil Pattern or mcrvement of the trrnsom will activate it.
No sensors are shown on the door below the transom becrugs
it is not relevant to this digcussion. Howeverr if a magnetic switch were usedt it could be connected in series with the protective circuit connection to the terminal block of the nGrrcury switcht (at B. )
3l
TRAPS
Although the cfrp trap goes back to the stone age of burglar alarn technologYr it continues to afford a sirnplen inexpensive means of nonitoring a variety of situaticlnst such as ventilator openitrgsr windswmounted air conditioners, garage doors, etc.
T
M
B-
A
I len+l
I
The clip trap shown above consists of two parts: A is the pfug, B is the jack. Eoth parts are seen in the center diagram with their trEtvers onf engaged as they would be in actual service. There are two dif{erent hrays to use a clip trapl oor is carled a ,, live trapr,' the other is a "dead trap. "
Protec t ive
Ci
rcui t
Figure tZ-l An example of a live trap is shown abover applied to the gritle of a ventilator duct: Note that both legs of the protective circuit wiring are connected to the scre!{ terrninals of the jacx (B}, which is {astened to the wall just below the duct. The continuation of the protective circuit is connected to the screh, terminals of the plug, (A). The protective circuit wi.r'ing is securely {astened to the r+all at the points
marked X.
hlhen A is plugged into B, the
path of electrical
continuity
may be
seen by examining the diagrams of both parts: The btades sectn protruding downward from the plastic base of the clip are metallic extengions of the terminal scrertls visible on top. The hooked posts in the center of the jack ?re shaped strips of spring steel, spaced to hold the
clip's
blade firrnly when it is inserted.' 32
It is not uncommon for a burglar to wriggle through a ventilator duct and cut through or kick out the interior grille. As seen in Fig. 12-1r i+ the grille is kicked out the clip witl be dislodged from the jack. If the hurglar reached through with a tool to cut the wire the ef f ect would be the sarne, thus the name live trap. This clip trap arrangement enables removal of the grille for cleaning and maintenance without need to disassemble a morc! permanent type of wiring. A typical use for the dead trap is that of a floor-level trip wire, which is use#ul in simple, "lohr risk" applications such as a tool shed, or the trip wire may be passed through a hole in a wall and stretched across an exterior driveway or path, enabling the outside of a premises to be nonitored by an interior alarm system. The same type of clip trap lnay be used for a dead trap, with two major differences in the wi ri ng: IJ
o t{
0)
IJ
o q) ! o t]
Ar
In the above rxample, the jack (B) is wired in series into one leg of the protective circuit (in the usual mannEr. ) The plug tA) is no.! Insteadt a used as a Live continuation of the protective circuit. short jumper wire (C) is connected acro:rs its terminals to affect (Review the drawings of continuity when it is plugged into the jack. the two parts if this is not clear. ) (at least 2O* test) t is atA length of fine, black fishing line, tached to A and stretched at baseboard height, where it is fastened at an anchor point shown as X. Trip wires of this typet strategically economical situated within a darkened premises are a simple, efficient, way to protect a low-risk premisrs. The floor-levef trip wire is but one! way to use a dead trap. Another technique is to stretch the wire across a closed doorl tack it to the lohrer sash of a window, or use it in any manner dictated by comnon sense and imagination. Its range of applications is limitlBSs. Any action which causes the plug of a dead trap to be withdrawn from its jack will initiate an alarm. Any action which causes the plug of a live trap to be withdrawn from its jack-- or revers thr suparvisod trip wiru (ag shown in Fig. 12-l)-will initiate an alarm' 33
VIBRATION
DETECTOR
contenrporary burglar alarms is an The vibration detector used in which was devised by the British adaptation o{ the "trenolo" switch, cloak&daggerservice(duringWhl-II)fordetonatingvehiclebombgin was designed to close a circuit sabotage operations. hlhile the tremolo circuit' upon sensing vibration, the burglar alarm version c'Pens a
Thedeviceisapprox.thesizeofpackofchewinggu'll. side and front viewg of a typical vibon the le#t are (with its trover removed. ) A is the ration detector, J+ pendufur, a smalI, cylindrical brass weight fastened to tf,in strip t:+ spring bronze' B is a pair of terminal "screws. The base of the device i5 non-conductive plas* A Note that another thin strip of bronze extends tic. under the from the lower terminal screH, upward and gengitivity B p=,.d.,I.,'. Not shown in this diagram ig a adjustment screw, which adjusts the spacing between thrg pendulum and the bronze strip beneath it' (e.9. a The device is fastened to a solid, vibration-frFe surfacer by extremely forceful tneanst brick wall), which might be penetrated etc. (Breaking through cellar wallsr of such as hammer-blows, orirling, entry method when the adjoining commercial pre6ise5 is not an urrcommon screws but epc'xy stakes are high enough. ) It may be {astened with iement provides a better union with the mounting surface' are apPlied to After the device is fastened, the probes of a meter adjustment Eicreu| is slswly its terminal screwg and the sensitivity closed contact between the rotated cl0ckruise until the meter indicates by swinging fully to the pendulum and the conductive strip beneath it, needle The adjustment screw is then backed of# until the meter right. pounding by alternately drops back, i.naicating loss of contact. Then,sensitivity srcrertlt the the re-adjusting and surface on the mounting wall' protected device is,,tunei" to detect a forceful attack on the indication bJhen using a meter (set to read continuity) the proper movement wide fixedl will occur as a slight bounce o{ the needle, not a blon A sharp closEd circuit' solidly to the right "= o.c,rts r*ith a (within the cause 'against the mounting surface a 12' radius) should protective a needle to movEl sfitfrtfy and fall back. Keep in rnind that to the circuit relay is extremely "fast" and sensitive, and will rerct it; through slightest disturbance in the flon of supervisory current a rePresents fluctuation of the meter needle therefore the slightest sufficient disturb'ance to trigger the alarn' will not be as Eonsider that a blow struck while testing the device nall t so the the on 5,evere as would be those struck in an actual attack to adjust not careful difference must be experimentally projected' Be routine such from the sensitivity too high t 07 false alarms will result is the sensitivity hlhen events as thunderstorms, passing trucks, etc. and terminalg the to the prot=clive circuit properly adjusted, connectgevice. (Not too tightly, or the sensitivity scre$, the cover on the adjustment might be altered. )
h
34
l l l
LACING tB=E!t=tttEEMEIGII
I=I-tt--I---3
hlire facing is a very sirnple $tay to monitor a door or window that is never usedt a weak section of wall, a workshop skytight and situations where the use of switching sensors, (magnetics, rt.. l, is neither netressary nor practical -
Lacing is simply a continuous pattern of fine, brittle r*ire, (either bare or in=ulated), which is fastened in an even pattern across the opening or barrier to be monitored' The door shown above operns inward and is fitted with three panels, any of which could easily be kicked in by a burglar- It is situated in an area lrhere appearances are not an important contrernr Scr lacing is the ideal sensor for it. The pattern was cFeated by driving ordinary carpet tacks into the dosr-frame on both sides of the door at 2" vertical intervals. The tacks are driven in only partially, leaving about !/g,, extended to wrap the lacing wire around the heads. Begin forming the pattern by wrapping about four turns around the {irst tack, leaving a short tail hanging to splice into the protective circuit. Then stretch the lacing r+ire acr(]ss to the corresponding tack and wind four turns around it. l"love the wire down to the tack below the one just wound, wind another four turns and stretch across the door again. Repeat the Frocess until the pattern is completed, leaving another tail hanging at the last tackt then gently drive the tacks almost flush with the wall. (A hard hammer blow r"litl easily break tne wI?EISplice the pattern into the protective circuit as shown and the job is finished. hrhile a lacing pattern is easy to by-pass, (by attaching a jumper to the strands at the top and bottom), access to the pattern would be necessary- To penetrate this pattern without breaking any strands would require careful, skillful cutting of the door, which only a sophisticated thief is capable of. This type of sensor is not recornmended for any type o{ high-risk application, however it is adffiate for protecting against the averager unsophisticated, ',crowbar', burglar. Lacing patterns are! useful for nonitoring potentiat points of forceful entry onto low or average-risk prernises such as {iimsy, adjoining walls, unused doors, windows and skylights, etc. Ventilator ducts are cornmonly protected by fastening a laced frane (next page) over the interior grille. 35
A laced frame is easily constructed from two sections of wt:od {rame (of optional shape and size) which are made from l" x !/2" strips. Thumb tacks are uged to stretch the lacing onto one of the frame sections. lrlhen the pattern is completed, the second section is applied over the first (leaving the two connecting tails hanging out), a hole is drilled through each corner of the frame and it is fastened over the ventilator grille. Againt this type of senstrr should be used only when the maximum level o{ attack sophistication is that of a burglar squeezing through the vent and kicking out the gritle-- breaking the lacing strands at the same time. (This diagram showg the completed fl-ame, not the unfinished sections. ) l"lore sophisticated versions of laced screenq are available, made to order according to size. One type is a finely-crafted window screren that looks ns different from ordinary screen but has insulated lacing wire woven into the screen material. Because the cutting or remtrval o{ window screEns is an extremely cornmon practice in regidential burglaries, screens of this type are uniquely efficient periroeter msnitoring devices. They, will activate the alarro if the screen is cut or removed. Also available from commercial suppliers are pre-assembled screens which are rnade {rom basswood dorrels that have the lacing wire imbedded in them. The wiring of these screens incorporateg both legs of the protective ci,rcuit rather than just one, as a measure of protection against 'by-pass' by the jumper method mentioned abtrve. This technique presents the burglar with a random arrangement of strands, some of nhich are extensions of the + (positive) leg o{ the protective circuit and sone of which a;e extensions of the - (negative) leg, rf a jumper is attached to a positive rnd a negative strand, the protective circuit will be shorted at that point and the alarm will be activated. ($ee the section on SH0RT trrRcurTs if this princitrle is not crear.) The wire used for lacing is available fron specialized suppliers and is designated as hard-drasrn ctlpper wire. This type of wire is especially suitable {or lacing because of its brittle, non-re=ilient nature. It will not stretch as will normal copper urire but will break easily i+ stress is applied to it, 36
BhIITCH ]'IAT
Switch mat is available in rolls of 1O to 25 +t. long x 30" wide and may be cut to any desired length for placement under carpeting. The strips, arranged one next to another and mat is made up of individual sealed r*ithin a thin, plastic cover. Each strip is an individual senscf,r, consisting of two metallic strips which are held apart by a resilient, insulative material. lrlhen the mat is compressed the two metallic A wire tail strips are farced into contact, which closea a circuit. When the mat is intact, the wire extends from each metallic strip. serve to conjoin the separate strip segments. The full-length tails nat may be placed beneath a carpetr oF it may be cut up into individual ovErr a wider area. Each segments (stripsi which rnay be distributed strip) cut from a mat has it's own wire tails for sectisn (individual Bo a full size mat will yield attachment into a protective circuit, several smaller sections Er a large number of individual strips. tl rl tl rl tl rl tl
tl tl rl rl tl tl tl
tl tl tl tl tl tl tl
rl rl rl rl rl rl rl
rl rl tl rl rl rt rl
tl rl tl rl tl ll rl
rl rl tl tl tl tl rl
tl tl rl tllt rl ll tl
lr lt lr lr lr lr
rl tl rl ll ll rl ll
rl ll rl tl rl tl rl
t:
PF: DT EC T T t/E
RCLJ
T
Eecause of the simple nature of gwitch rnat congtruction, which arnounts te several pairs o{ metal contacts (strips} held apart by thin
springy material, it maintains an open circuit until conpressed, (by a footstepn etc. ) Because a sensor which maintains optn contrtrtr cannot be series connected into a protective circuit, a device called a rat converter must be used. A mat converter contains a simple circuit that reverses this status, presenting a clond trgntact status to the protective circuit until the mat is compressed-- at which point the converter shows crpen contact status. An alternative to using a mat converter is to the protective circuit in seen below: The rnat ig wired directly parallel (compare the connections in both diagrarns) so that closure of blhen this wiring method is the rnat's contactg irnposes a rhort circuit. used, the protective circuit battery cannot be wired as shown in Fig. 3I, in SHtrRT CIRtrUITS. Review the section on SHURT CIRCUITS i+ this principle is not clear. rl tl tl tl rl tt tl
ll tlrl tl tl tl tr rl
rL |t rl rl tl tl rl tl rl rt tt tl rl
tt rl tl rl rl tt rl
tl rl tl tl tl tt rl
tl rl tl tl tl tt tl
tl tl rl rl tl tl rl
lr lt lr lr lt ll lr
tl rl rl rl rl tl rl
rl rl tt rl tt tl rl
37
PROTECTINB BLABS r-tr-tarr-t-lralll:--llt-rr-r'lrr!l'lttrl
notion that A number of imaginative moviEr =iequences have created the glass-cutter a it with scratching by plate glass is easily penetrated handle. and removing the scored section with a (suction-cup) glazier's virtually is it crovies, the for lJhile this is a very good trick manner! The impossible to penetrate a mounted glass Pane in thishand and rigid an experienced for calls prop", use of a glass cutter pane is the Once scribed. being support directly Uitrina the section a to effect side opposite the {rom ,.ribed, it rnusi EEGarply tapped clean separation. remcrve the entire Burglars do not use cutters on glass. They either ptacet or they smash in it hold that pane b! prying away the moldings burglar will panGlr sophisticated glass a it out! Befoie smashing a and supgtrips shattering, minimize to tape duct of cover it with wide TherenellsPaPer. soaked of thicknesses several press the noise with diswill noise of factor the that confident fore one should never be pane, to a smaller glassr espelcially breaking courage a burglar from gain entrY. method of protecting glass is to apply a continuous An efficient on the strand of conductive foil ribbon around the edges of a Pane protective into a strand the of ends the intrrior side, and connect If the pane is shattered, the {oil conductor (which is the circuit. equivalent o{ a strand of fragile wire) will be torn, interrupting the which triggers the flow of current through the protective circuit-al arm.
job Applying feil to glass is a simple procedure but making a neatpatBy experimentally applying a foil o{ it requires sooie practice. glasa, then scraping it off and doing it overt pane of tern to a small The follovring is a list a few hours. in mastered the technique may be of the technique {or description a with along of the item:i required, applying foil to window PanErs. 1>
2>
3>
Foitl comes packed on 1 rb. rolls of 3/8" wide ribbon. A roll contains several hundred feet, which is enough for dozen= of large windows. The most convenient way to work with {oil Fotl Dirprngrr above the working surfatre =itr the ribroll the is to suspend as it is applied. This keeps it downward drawn bon may be prevents tangling. A special dispenser is and out of the rray It is simply a pair of flat discs made for this PurFgl:;e. held in place by a screl{-cln are and roll the that clanp onto tlne digc for hanging the the from extends knsb. A bracket (If is not available the disPenser a nail. a on dispenser g1n heavy string-) or wire a loop hung be nray roll of {oil white varnish is Varnish, Thinner and Brughr t}'dinary (A small can is plenty' ) used as both adhegive and sealerAlso, a can of benzene or a similar thinning agent will be 38
needed, along r*ith a short, wide-mouth jar. An ordinaryr peanut-hutter jar is ideal.) artist's brush is used to apply the varnish. 4.)
EL dJ
6>
(A snall t clean 3/8" flat-tip
squeegeet A very handy item to use as a squeegee for Rubbermaid smoothing +oil ribbon to a glass surface is a (Bne that's off. dishwashing scraPer, with the handle cut well-) very work goftened won't by hot water been used and matchbook of a shoutder If this itern is not available, the cover may be used. trhalk and l'larking &ridrr An ordinary piece of Tailor't chalk is perfect for marking a (white or yellowl tailor'5 guide-line around the edges of a glasg' Pane. The guide lines align are marked on the ou-tside of the glass and are used to guideThe insi4e. apptied on the the pattern as the foif-s lines are marked by running oner edge of a rigidr 5'quare guide alongside the edges of the window frame while holding the chalk against the opposite edge of the guide. An ideal marking guide is a 2-Lf2" square block of wood for a small window, t]r a 5-1/2,' block {or a large window. In a pincht a deck of playing cards ctr a cigarette box rnay be used. splicing Toolr blhen an applied strip o{ foil is torn ar scratched it is easily repaired by splicingr oF aFplying a patch that overlaps the separated ends. lrlhen a splice or a patch is completed, it is necessary to puncture several holes tnrough the overlapping ends of the patch or splice. A special tool is available for this purposei it is a small, multitoothed disc, mounted like a wheel on a pencil-size handle' This tool looks very much like a miniaturized version of the gadget used to cut a Pizza into sectionsr but instead of a edge the blade has pointed teeth: Instead of cutiutting ting, the wtreet's teeth penetrate the over-lapped sections If this tool is not available .r*ry neatly and efficiently. (No less than a dozen holes any'type of pin may be used. ) overlap. each should be punched through
SPLICINB FOIL
BRUSH
DISPENSER
A short steP-ladder is
TOOL
needed to Provide a comfortable
usuallY 39
hrgrking Fosition through the separate stages of the foiling procedure. I+ the roll of foil cannot be suspended and centered over the working surface, it should be hung either on the belt or on a hook screwed into the edge of the ladder shelf' The Be{ore beginning, fill the wide-mouth jar halfway with thinner' glass mugt be cfeanr and the areas to be fsiled should be wiped with denatured alcohsl. or mineral spirits to reoove any oily film. PROTECTIVE CIRCUIT
\\
\
\.
'.--\
\
\
of a finished foil pattern applied to a Above is an illustration room or a pane of glass r*hich might be a picture window in a living pattern the plate glass window in a commercial premises. Note that corright-angle of six, begins at I and. progresses through a seguelnce upper the at pattern is terminated ner bends. In this example the center o{ the window, which does not imPly a gtandard or a rule: A foil pattern rnay be terminated rnynhrru on the window. The determining {actors are appearance and wiring convenienceThe {otlowing page shons a numbered sequence of tha steps involved in applying a {oil pattern to a window pane. In this case the pattern terminates at the upper left edge of the frame. The faintt broken line represents the guide-line marked with tailor's chalkThe first step in the procedure ig applying the adhesivel If the varnish is not fresh, a few drops of thinner should be stirred in to A thin coat is applied along the avoid a thickn gultmy congistency. Ll?" of drY spatre next to the frane guideline, leaving approxirnately will be tails to trhich the {oil block, for attaching a take-aff the guide-line through the coat along connected. Eontinue the varnish there. stop and progression shown in Steps 2 & 3r 40
i I I
--l
---''l
\
I I
- --t I I
lt
I
i I
\..
I
l_ -
-
-T I
-
t:
i
-
-l
-t I
I
I
i
I
_l \-I
I
i
;
I
I
I
I I I
L_
_-
_--
-
i
-J
i i
i
'-
IT
I I I
6
I
I
I
I
\
I I I
J
l7
l-\
J
i---tt
0 {.
I
l--.
--l I I
0
r^ 9
?
I I
+
it
{'l
t----
--J
I
4l
\
I+ the adhesive coat is continued around the entire Fane before beginning to aPply the foil ribbon, by the time the fourth or fi+th sections are foiled the adhesive will have dried out on the remaining While an experienced installer is usually abte to aPPly the sections. xith adhesive coat around the entire pane and folIow it rapidlyshould accurately positioned strips of foil r a beginner straightr After three sections of prog.===ion slowly and carefully. the {ollow the {irgt section adhesive coat aie appliedl wait a {en ninutes until If the ribbon is applied over becomes tacfry, (sticky and almost dry.) freshly laid lwet) adhesive, it will slide around and tend to fall away from the glass' is held by the thumb and A short section of +dil, (see Step l), 6 inch leader dangling from the {orefinger of both hands, with a 4 left hand, This {irst section is aligned urith the guide-linet pressed in place with the thumbs and srnoothed with a fingertip. The cclrner bend is made by simply folding the foil over itself as shonn in the diagran below.
0
Fold the first bend upward as :;een in SteP 2r then fold the second bend and appty the third section, which is the upper, hori=ontal strip seen in Step 5. Pause at this point, dip the squeegee into the thinner to lubricate it, then use it to smooth the foil tightty to the glass. Shake off the brush (which has been standing in the thinner jar to prevent the bristles from hardening) and aPPly a line of adhesive to two rtore sestionE, (4 & U. ) Then follow the same procedure through Steps 6 & 7, but leave another l/2" of glass dry betwcen the edge of the frame and the last line of adhesive applied. hlhen the last strip of foil is applied, tear the ribbon from the roll, leaving another 4 to 6 inch leader hanging loosely as seen in Step 7, The darkened arrcrhrs in Step B point to the tcrminel rndr of the foil pattern. The ends of the ribbon are attached here to a pair of foil take-off blocks42
FOIL TAKE-OFF
BLOCK
A take-off block is a small, plastic platform with a 3./8" recessed channel that acconodates the hanging the foil ribbon. A metal retainer plate (seen in diagraml is fitted into this channel and secured by a
Foil Strip
sloping edges and ends (feaders) of the upper right small screw.
Retalrrer Plate
1 -
The take-off block has an adhesive pad on its underside, by which it {astens to the glass surface. The reason why t/2" sipace:i are left unvarnished at the edge of the {ramE! near the terrninal points of each pattern is to accomodate the take-off blocks. These ll?" spaces should be wiped clean with denatured alcohsl before applying the take-off blocks, or the adhesive might fail.
After the blocks are firmly mounted, apply a +inal dab of varnish at the foot of each blockr squeegee the hanging tails of ribbon right up to the edges of the block, smooth the hanging tails of ribbon into the channel o* the blockt seat the retainer plates and tear off any excess foil. The retainer scrErhrs are used to connect the foil pattern into the protective circuit. To finish the job, apply a liberal (but neat) coat o{ varnish over the foil pattern to geal it, Step q depicts electrical continuity through the conpleted foil pattern. To test the pattern for continuity, apply the probes of a meter to the terminal screws o{ the take-off blocks. The foregoing procedure describes the "old $ray" of applying foil, which is the best way, The nen nay is essentially the sam€!, except that a time-saving, "self-adhesive" type foil is used, which requires no varnish coat. This type of foil is backed with a peel-off strip, much like a band-aid. It is much easier to applyl one just strips off the backingr sticks it on and applies the sealer coat. llhile everything ;ePpears to be the same, the problern with self-adhesive foil is that it's distinctly thicker, heavier and stronger than the fragile, non-adhesive variety. Because the objective of window foil is to separate (tear) easily when stress is appliedr the stronger it is the less ef{iciently it will perform. This brings up a very inportant factor which was not covered above: 43
PliThe ,'old-{ashioned," non-adhesive foil is extremely soft and practice of a beginner's stage first the so easily, able,, It stretches of foil ribshould be that of experimentally stretching a few lengths point. l'lhen apbreaking and tolerance its with bon to become familiar pressed onto it is ag be should rtrrttrhEd section each plying the foil purpose of The just tapeadhesive like on laid than Lfr* gi"=r, rather glass t'rill that the on skin tight thin, produce a to this stretching is easily separate when a crack oPens beneath it' arre disbJhen plate glass shatters, Eeveral generations of cracks pattern is foil tributed dor+nward and outward. Even though the typical just a few inches from the edges of the pane, it is extremely "ppii"u rare that the cracks rrill not extend down and out to pass underneath the foit pattern at thb sides and botttrm. A tightly stretched skinof ofa non-adhesive foil is far rnore tikely to separate from the stress time 5o the extra fine crack than is the heavier, self-adhesive type. paid off in many has way" the it doing in "old involved and wgrk i nstances.
a gecfion of foil is scratched or tsrn it can easily be repairA Fazor blade is used to dress the scratched ed by applying a patchl gap between them. A rePresents the dresclean a or torn-endsr-leaving sed ends of the damaged foil section. B represents clusters of Punctures through the patch, wedding it to the severed ends beneath. trlhen
Strip
Strip
BA Dip a pad of soft steel wool {OOO grade) in thinner and use it to (qentiy) rub.altay the dried sealer coat of varnish from the trimrned them rrrA=. Then aFply a thin coat of fresh varnish to the endsr spanabove nith a 2" tengtn o+ new foiL (seen as the shaded area in the splicdiagraml and iqueegee this patch firmly in place' Use either a ing tool or i pir, to puncture at least a dozen holes through the overlapped sectiBnsr as ghor*n below' Patch
, t,r.i \ l+ll+l
r,,,l,l
I
JJiltJr /
Patch
BREAK
Above is a,side view of a broken strip o+ foil which has been spanthe ned with a patEf,-I The clusters of arrohrs denote punctures. Finish probes of patch by applying a sealer coat of varnish. Then aPPly the(Di=connect rneter to both sides o+ the patch to test talr continuity. the foil pattern from the protective circuit before making this contin-
uity test,
)
of multiple It is sonreftimes necessary to aPPty foil to a grouping pane with separate each terminate prictical to pane5 in which it is not diafollowing The protective circuit. a separate connection into the situation. gratn depicts this kind of 44
CIRCUIT
PROTECTIVE
This diagram represents two horizontal rows of satall glass Panes. A separate {oil pattern is applied to each pane, The dots seen at the termination points of each pattern represent take-off blocksNote that there are only two ternination points on pane {lt. The arrcl$lEi point to a pair o{ short junper wireg, (cut from ordinary 2? ga. Protective circuit wire), which connect the pattern crn pane *l to the pPattern on pane *2, Pane *2 is connected to pane t31 3 to 4 and Eo crn. This arrangement of panGrs is not typieal (except on garage doors. ) The purpose o{ this diagram is to show that the basic configuration of a foil pattern should follot+ the contour of the pane it is applied to, and that the termination points are determined by the wiring requirements. Note that each separate pattern is a basic square, but the termination points vary according to the connection requirernents. The patterns on each of the separate panes are ccrrnected in a r,ray that a*fords series continuity throughout th entire sequErnce. The final ternination points are seen at the top of pane llB, where the entire grouping is connected into the protective circuit. Observe that the protective circuit wireg are! rnarked to indicate (+) wire is cut to polarity ( + - ). . In this example, the potitivr accomodate the connection. Using a pen or pencil, follow the + leg o{ the protective circuit through the entire "maze" a{ connected patterns, from pane llB to pane *11 and out again. This will grephically demonstrate the principle of a continuous selies circuit, showing the path volt that the 5 supprvisory current witi-Ellolr. to applying foil ribbon is to use . specially deThe alternative signed sensor called a ELASS-BREAK DETECTOR, a small, circular device that attaches to a glass sur{ace by means of a self-adhesive backing. 45
_......-F
3
The single advantage of glass-break detectorsr BS opposed to foil ribbont is ease and simplicity of installation: Atl that is required is to peel away the protective coating frorn the adhesive backing on the device and press it in place on the glass, (after wiping the mounting surface clean with alcohol!) A pair of rrire tails extend from the device for splicing directly into the protective circuit wiring. Before this connection is made the probes of a meter are attached to the leads so the sensitUfily level of the device can be adjustedt
hlhife a glass-break detector is not classified as a "vibration detectorr" it operates by sensing the high-frequency vibrations nhich are generated by the sharp crack of shattering glass.
The device on the right (above) is rated to detect glass hreakage within a 52 square ft- area, which works out apFroximately to a 4' x B' section. The diagrarn on the left represents an B' x B' pane with two detectors applied to the glass and wired into a protective circuit.
The drawbacks o{ using glass-break detectors instead of foil arGt cost Per device and a somewhat greater potential 4or false alarms. This does not imply that glass-break detectors are inherently falsealarm Prone. But they arE! activated by sensing a high-frequentry vibration-which might be generated by events other than actual breakaget such as a flying pebble striking the protected pane, etc. A high-quality glass-break detector is capable of providing years of stablet reliable protection, and is recommended for large, stationary picture windows and plate store-front winPanes such as retsidential dons' Howevert they are less practical for use on smaller, movable Panes such as the average double-hung and sliding aluminum window. The problem here exists in the volume of individual detectors needed and the requirement to wire each of thern with a flexible cord to enable unimpeded movement of the sash. (Remember that the detector is applied to the glass and its wiring must be carried onto the staticlnary, surrounding area. ) The problern of carrying the protective circuit onto a movable window sash is sqlved in the following manner. 46
PBOTECTIVB CIRCUIT
The device on the left is a sirnple but clever, two-part set of contacts that serves two purposes! It provides continuity from the protective circuit to the {oil pattern and acts as a sensor to detect rnovement of the sash-
A is a plastic block with a pair of screw terminals cln top. On the bottom o{ this block, (not visible in the drawing), are a pair of metal plates which are direct extensions of the screw terminals. This block is fastened by screws to the window sash shown on the right. B is another block with a pair of screl'r terminals on its front. This block ig {astened to the window frane with screns. Protruding from the top of this block is a pair of lea{ springs which are aligned to contact the metal plates at the bottom of A nhen the window is cloged. These leaf springsi are direct extensions of the screw terminals on the front of the block. Note that the foil pattern is connected to the scref', terminelsi on Ar while the protective circuit is connected to the screw terminals on B. hlhen the sash is closed, tight contact between A and B is effected by compression of the leaf springs of E against the metal plates of A.
47
PHOTOELECTRIC I}ETECTOR
The photoelectric detector is commonly referred to a!5 an "electric eye. " It consists of two separate parts, a transmitter and a receivert each o{ which operates independently, served by its own po}'tcrr source. The receiver of a modern photoelectric contains a hiqhly sophisticated
receptor cell which is sensitive to a pulsed, infra-red beam. Its companion transmitter projects a beam which is invisible to the naked eye and cannot be defeated by superimposing a secondary, bypass beam. (Early photoelectrics emitted a highly consipcuclus beamr and could easily be comprornised by aiming the beam of an ordinary flashlight into the receiver to override the companion transmitter. ) The transmitter serves the single purpose of emitting a beam, which is aimed directly into the eye (lens) of its companion receiver. The beam excites a photocell within the receivGlrr causing a pair of internal contacts to sr*itch closed. These contacts are continuous trith an external pair of terrninal screwst which in turn are wired into a probeam is momentarily interruptWhen the trangmitter's tective circuit. switch openr activating the alarm. instantly internal contacts ed, the Photoelectrics are available in a variety of distance capabilities, ranging from 50 to I'OOO feet and weatherproof versions are available Modern photoelectrics are generally stable for outdoor aptrlication. when properly alignedl but both transmitter and receiver must be sevibration-free mounting surface. The imcurely fastened to a rigid, portance of this requirement increases in proportion to the distance between transmitter and receiver.
Control
Panel
AC Porer
AC Poxer
-
Photoelectric
Eean
\/
)
TIIIDOTS
The layout shown above depictg a photoelectric applied to a very industrial situation, a factory corridor with a number of winIt is dows along one wall, spanning a distance of approx. ?5O feetl often dif+icult to protect such an area with foil patterns or individual window gwitches because of multiple pane:;t (often broken) t and deteriorated stone and metal fittings. common
48
The diagram shows a photoelectric transmitter (T' mounted at one end of the wall and the companion receiver (R) at the other end. The beam is projected across each of the eight windows and positioned so that an entry through any window would unavoidably interrupt it.
Foth transmitter and receiver are powered (via lZV DC transformer) by lt(t ACt but both units rnust be equipped with an internall tricklecharging standby power supply to maintain stability during momentary ar prolonged polrer loss. No other sensors are shown in this system. The receiver is wired directly to a protective circuit which is energized by a power supply within the control panel.
There is an endless variety of possible applications for the photoelectric detector' each of which must be evaluated on the basis of environment and other circumstances. Eurrently, the nrost popular type of photoelectric detector is the cleverly designed version shown below-t*hich is disguised as an ordinary wall receptacle.
There are two parts to this device, one of which is simply a reflector, It, too, looks like a wall receptacle but its only purpocie is (A) to the receiver (B), to bounce the beam back from the transmitter both of which' are built into the same housing. The transmilt.erf receiver unit is {lush mounted in the samcl mannElF aE any normal wall receptacler or it may be substituted for an Glxisting rctceptacle and connected directly to the Atr por.rer. The ref lector (C) is then situated on an opposing wall and aligned. (Alignment is perforned by simple strreh, adjustments. ) t{hile the range of this device is a liberal 73' it is most conmonly.installed in a narroril entrance corridor, thereby assuring tnany years of stable, trouble-free service. The nature of this device calls for fully concealed, in-the-wall protective circuit wiring unlesg the protective circuit is brought in through a small hole drilled straight through from the rear of the mounting wall, (which might be a closet, etc- ) In this case, the protective circuit r*iring may be carried along baseboards and door moldifigsr as explained in the section on INSTALLATION NOTES. 49
AREA PROTECTION DEVICEg
The devices used to monitor doors, windows and walls (such as tnagnetic, plunger and leaf switches, foil patterns and vibration sensorst etc. ) are classified as per iteter protection deviEesr for obvious reasg1n5,. hlhen a device is ernployed to monitor a specific volume of 5Eatrer it is called such as the interior of a roorn or a part of a larger €r protection device' space protection or device, an area
Before the photoelectric device (described in the foregoing section) along, the only alternative to perimeter msnitoring was the imagtrip-wires and inative application o{ "trapsr" such as clip-trapst switch mats situated in strategic locations. The example given in the photoelectric description is but one of many possible applications of this very flexible device, its full range of possiblities being limited only by the installer'E resourcefulness and the physical environment, trarn€r
The photoeleqtric detector is an area protection device. It was described separately because of its relatively simple nature and limitations in comparison with the sophisticated devices to be covered in Before proceeding it is irnportant to mention that the this section. of these motion detectors is of no coneeoporetlonrl tophitticetion This sectinn will describe the individual qurnrr to the insteller. Installing devic€lsf how they work and their rErspective limitations. and "setting up" any motion detector is no tnore di+ficult than installing a simple switch-typcr sensrrr. There presently are three separate types of motion detector devices available for burglar alarm application, these are l'lItrRO-hlAVEr ULTRASONIC and PASSIVE INFRA-RED. These device are made by nurnerctus manufacturers, therefore they ctrrner in many shapesr sizes and degrees of For the most part, however, the physical configurrelative quality. ation o{ these deviceg is basically similar.
FROTECT
IUE D IRCUI T
118
RC
The figure above depicts the rear panel of a typical area protection device, showing i.ts two wiring requirementgr The device is connected into the protective circuit at A by means o{ a pair of scr€}}', terminalst The other connection in the same manner ag would be a simple switch. (B) is the independent power requirement, which is usually facilitatad (The transformer is included as a separate by a plug-in transform€lr. hlhile most component and is connected to the device r*ith 22/2 wire.) of these deviceF may be situated on a shelf, each is equitrtred with a bracket for mounting it on a wall (which is recommended for stabitity and protection from damage and tampering. ) 50
o
OX
I
STFBLE
f,CT I VfiTEO
The front panel of a typical motion detector is depicted above. In the center is a "screened emitter aperturer" which is a hole through (in this r.rhich a f ield of active Ernergy is projected. To the right figure) is a tiny LED called the "walk-test" light. This light flashes on whenever the device is activatedt visually indicating its sensitivity and serving as an aid to adjustment.
Adjusting the device is usually a matter of rotating a snall knob, wheel or strrehtt which is also located on the rear panel. Turning it clockwige increases the'ranget counter-clockwise decrease:i it. Another way to observe the sensitivity of a motion detector is to attach the probes of a meter (set to read continuity) to the protective circuit connecting terminals. lJhen the device is activated by novenrent within its adjusted ranger the meter needle will swing to the righthlhen the movement stopst the internal circuitry of the device will stabilize and the needle will then drop back to the left. Installing a motion detector device in a burglar alarm protective circuit is sirnilar to installing a receiver clr a tape deck in a stereo trompctnent systemr (and generally easier.) One needn't know anything about vrhat makes the component "tick" electronically. It either works or it doesn'tt which is immediately apparent. I+ it doesn't work, it is removed and returned for service. I"IICRO-bIAVE:
(
(
.
ilICNO-H8UE DETECTON PETTENH
The l{ItrRO-hrAVE motion detector emits a focused beam of RF (radio frequency) energy, typically at 10,525 EHz, which is roughly the frequency of operational RADAR-- including highway speed detectors. projects en RF beam, which is hlhen the device is switched cln it re{lected by any solid object within its range. Its internal senstrry 5l
;rpparatus adjusts tcl the reflective constant, that the absence of any chinges- The movementr oF apFearafrce, of any issolid within the path of the bearn alters the constant, .-,r=in{t a pairobject of internal contacts to open, which activates the alarrn_ The pritnary advantage of I'lIcRu-hlAvE is its comparatively long range!r which is typically 3oo' long by t5' wide at mid-range. Another advantage is its ability to penetrate most rnaterials (exiept metall enabling one device to monitor tnore than one room ctr arela within the sa,ne prernises. However, inherent in this capabitity is an outstanding false alarm hazard-- as seen in the HItrRo-tJAVE PATTERN diagrarn:
This diagram depicts a t'lIcRo-hlAVE device mounted on one wall of an enclosed aFea and projecting its beam forward. In this the device is nst properly adjusted (or has "drifted" out of diagrap adjustment) and is penetrating the perimeter walls at the points indicated by arrows' Any rnovement occurring within this unintentionally extended field of coverage will cause a false alarm! Therefore, the factor penetration is the Achijres heel of the I'lrtrRo-l^IAVE motion detector. of Because t'trcRD-wAVE rnotion detectors operate in the same frequency range as highway speed RADAR guns, their radiations are detectablr by the same devices used to avoio ipeeoing tickets. ULTRA-SONItr:
AI /,?E -FF.,V-IC
L-€
'/-f
TB,F FT7,T [F,,F,V
The ULTRA-SBNIE motion detector emits ellipticatty shaped {ield {see diagram} o{ sound waves which are well anbeyond the range of hurnan hearing. The typical range of coverage is roughly 4olong -irr-r, by zo. wide at mid-range. (This range is consideiablv that available with a micro-wave device but there is no=r"ii.. penetration hazard. ) The lfansnlilte{- section of this device generates ultra-sound, which is monitored by the receiver section. The receiver adjusts to the stable level o{ ultraEilIE-Eent out by the transmitter and ,,listeng,, for any significant changes occurring in the ;shape" o+-tne sound waves, such as those which are caused by a solid object rnoving within the ULTRA_ soNItr field. The effect of disturbing an ULTRA-S0NIC +ield is simitar 52
to
cauging a ripple on a body of still water, but the sound waves move The receiver section of the device reacts to any disturbance by opening a pair of internal contacts. much faster.
A good quality ULTRA-SBNIC unit, properly adjusted and operating in a compatible environment, is capable of providing years of efficient, reliable service with littte or no attention. Proper adjustment nean5 sacrificing a {ew squarE yards of range to significantly decrease the device's false alarm potential. The typical range of an ULTFA-SBNIC device is mentioned above, hlhen the sensitivity is adjusted lower, (by rotating a thumbwheel), the elliptical pattern is proportionally reduced-- and so is the false-alarm patential. Even i+ maxiroutn range is required it is best not to adjust the device to its absolute limitt but to back aff a small degree. If a sFace does not call for maxinnum range sensitivity, the device should be adjusted to only the level required and not beyond, The ideal environment is quiet, clean and frcr of eny mrrvtmrlnt, whatsoever. Hoving drapest falling cartons or shelves and any kind of unanticipated physical movement within the adjusted pattern will activate an ULTRA-SENItrr so a cluttered environment is risky. Drafts are, a leading cause of false alarms, because dra{ts are perceived as rnotion by the ULTRA-SONIC. Forced air heating will de{initely cause priffiEr er=; will ,nany types of high-freguency sound wavcls. Some ringing telephones will activate an ULTRA-SBNIC device. The only way to know for surEr is to tlrt and obtrrv!. I+ a particular telephone seetns to caus€r activation when it rings, the frequencies may be altered by applying a small strip of electrical tape to the inside o{ its bells. Before an ULTRA-SONItr is installedr the environrnent nust be carefully surveyed for such things as whistling radiator valves, noisy heating and ventilating systems, hanrmering steam pipes and high frequency vibrations frsm passing traffic. The mounting gurface mu=t be absolutely free of vibration and movement.
Pets can be a problem if they cannot be appropriately isolated from an operating ULTRA-SONItr: Even a dog barking in an adjoining roorr could activate it. l"lost pets, €lspclciatly the littler onesr are receptive to high-frequency sound wave=; which, in sElmEl cases, causes thern great discomfort, On the positive siden it has been dernonstrated that these motion detectors o{ten serve the duat purpose of repelling rodents and certain insects from cellars, attics, etc. Ultra-sonic units are sold for that specific purpose-- with different nanes and significantly higher prfces, High-efficiency ULTRA-SONIC motion detectors are available for less than $2OO.OO. ULTRA-SONIC motion detectors, operating in compatible environments, have an impressive track record and are widely used by professianal installers. In spite of their early reputation for hypersengitivity, the major bugs have been removed and, at presentr the major cauges of false activation are improper adjustment, forced-air heating systems and such events as radiator valves that whistle when the heat comeg crn automatically at 4:30 am, etc. 53
PASSIVE INFRA-RED:
It'F,q,g-FFII
L7F fgf,,
TOF
Ffr .FF'V
to security The most recent application of sPace-age technology because called so pAssIVE detector, lnotion INFRA-RED electronics is the of a beam light the as such it does not emit an active energy beam, an of waves sound the or nicro-wave a photoelectri., it" radio beam oi pa5probes a* sensitive of number a instead it projects ultra-sonic; research, the "PIR" has sive energy. A product oi heat-seeking missile efficient detector of an as industry risen quickly tE popularity in the body heat and motion. glhen switched on, the PIR adjusts quickly to the arbjent temperature via the emitof its operating environment, which it rnonitorsigconstantly a surface radiating object an ied probes of passi,.6 r.r"tgy. I+ surrounding the of that than lower iemperature that is higherpIRor will detect it and activatct. CIbviouslyt (ambient) temperature, the compromised i+ used in an the e{ficiency o{ this type of device will be(room temperature) is close temperature environment where the ambient 98'6' is tcr that of the hunan body, which has attainSince its introduction, the relatively new PIR technology a pElnetrate can l'licro-wave stability: ed an excellent reputation for and it can be brick wall and pick up the movement of passing traffic triggered by be can Ultra-sonics signals. activated by =p,rtiorrt radio etc' A valves, radiator whistling dogs, ringing telephones, barking influences. these to FIR is not generally sensitive occurring change in temperature but PIR is sensitiva to a rrPidly changes or those occurring from weather not to gradual changes, such as exception is a forced air heatThe thermostatically contoifeA heating, ing system where a duct is likely to deliver a rush of superheated air directlY into the FIR field' bright sunA PIR device should not be aimed toward a window, because elevation in the sur{ace light striking a gtass pane can cause a rapid environment should be surveyed temperature of the pane, iftt---perating These are gteam PiPts; (eithin the -area o{ PIR focus for "hot spots. " lights that arei switched on by glr exposed or inside a wall), raditlots, 54
an automatic timer, etc. Fecau=e it is much easier to eliminate sources of rapid temperature variation than it is to elirninate ssund, vibration, and stray radio signalst the wider range of applicability and relatively low false-alarm potential of PASSIVE INFRA-RED is a good reason to select it over alternative types of area protection.
l,lith the exception of forced air heating, FIR is nst sensitive to the things that will cause an ultra-sonic to activate, and vice-vclrsa, nor will either device disturb sr interfere with the other. Therefore, a gaod way to combinet tnaximurn area protection with minimal false-alarm potential is to employ both devices in the same area, connecting them as shown below so that each devitre serves as a thunt {or the othei. I+ one device is activated by an accidental event the other remains stablet acting as a by-pass for the protective circuit current. But the movement of a human form entering hoth fields at the same tirne will trause hoth devices to activate siffiEaneously, opening both sets of contacts
This diagram shows an ultra-sonic motion detector (A) above (or in clcrse proxirnity to) a FIR motion detector (E), withsituated both devices focused in the same general direction. Note that the connecting wires of the PIR are attached directly to the connecting wires of the ultrasonic at the point indicated by arrows, This is a parallel connection and it functions in the same tnanner as a shunt lock (see the section on SHUNT LotrHs) with the PrR serving aE the shunt in this example. I+ the ultra-sonic activates but the PIR does not, the protective circuit current will simply conduct through the closed contacts of the PIR via the parallel connection. If the PIR activates but the ultrasonic does not, it cannot affect the protective circuit because the pIR (Review the diagrarn if this is not clear- ) is not nired in series. trnly if both devireE-Factivated at the same time nill the alarm be triggered. It doesn't matter which device is wired as the shunt, the ef {ect wi I I be the saflre. AUDIO DISCRII{INATORT As
its
name
implies, the
AUDro DrscRil.lrNAToR sensor
55'
,,listensr" via
by microphonesr f or- audio f requencies generated glassf breaking as such the typical noises made uuring forcible entry; creaking wood, etc'
rfne or r$ore amrli{ied
Ttr
F0HEFI SIIURCE
PF:frT
C
T]
c.f,?f]lJl r
VE
(as these devices are calA pro{essional-grade -
djscripjnate against routine environmental strunds, such as floor-waxing machines outsider etc., hut will activate i+ a drill or chisel hrGrrE! applied to its steel sur'taces. They are also suitable for monitoring school corridors and other premises where the attentions of a sophisticated thief are not anticipated. The second presumption is pretty close to accurate because mort burglars are un-skilled: If all locks are sGrcure against duplicate keys' simplt picking or frame-spreading techniques, and all windows are locked, 99Z o* the nation's hurglars will use relatively crude, forcible methods ts enter. Another factsr in favor of AUDIO DIStrRII,IINATtrRS is cost. When area protection is required in many separate roorns within the sarne premisesr the use of other types of area protection systems would cogt tnore! Ultra-sonic, photoelectric, infra-red or lnicro-wave dete'ctsr systems are available r'rith a central Frocessor and any number of remote head_q, but in larg.a quantity it is less expensive to buy twenty microphones than twenty micro-wave or ultra-gonjc heads for a raster/slave systemr ;rS these set-ups are called. AUDIO DISDRIHINATtrRS are classified as area cause they are not dedicated to monitoring one perimeter circuit, yet their pritnary purpose is fsrcible attack on a premises perimeter, (doors,
protection devices bespeci{ic point in a that of detecting a windows, walls, etc. )
EENERAL NOTEST
The principal value of perimeter monitoring devices (sr,*itches, foil patternsr etc. ) is that a burglary attempt will be detected in the initial stages of entry. The material cost of monitoring a large number o{ individual points around a premises perimeter wilt be less than the cost of rrne area protectisn device, However, when a contractor is hired to install a system, the cost of labor to install the perimeter devicesr particr-rlarly where a concealed installation is required, will far exceed the cost of several motian detectors. As mentisned previously, the ideal situatien is a perimeter system with one crr tnore area protection devices strategically located and wired into the protective circuit aE a back-up, in case a burglar gets past the perimeter circuit. This rneasure is particularly recomrnended in any situation where it is not possible or practical to monitor every individual point. of potential entryr Br- in commercial prernises where the possibility o{ a "stewaway" burglary exigts. A storuar,ray is a thief who conceals himself on a premises until it closes for the day, a technique which is comnonly used against large conmercial or industrial premises where no late-shift personnel or watchmen are employed.
57
PROXIFIITY EENSOR
Sometimes called a capacitance sens;or, the principle of this device is dernonstrated in many types of modern atrpliances and gadgets that use "ttruch sensitive" switching, in which the lightest touch of a fingertip to a solid, immovable surface is sufficient to operate the =witch. No pFessurer is required-- only the cloeie presentre tproximity) of a finger. Simply stated, this action exploits the small electrical charge (capacitance) inherent in a living body. At present, this technology is applied to elevator call-buttons, ecclnomy microcomputer keyboards, fight switches, tv and microwavE] trvErn controls, etc. The FROXIFIITY sensor used in burglar alarm systems is considerably more sensitive than those used in the applications mentioned above. In faet, when adusted to maximurn sensitivity these devices will detect the presence of a human body up to 24" away. However, when adjusted to its
level the device is susceptible to static electricity in the atmosphere.
maximum
disturbance (activation)
by
tr,?fur r This diagram depicts a proximity s;enscrr system monitoring a row of four (metal) +iling cabinets. A is the sensor control, which is powered by a plug-in AC transformer and connected into a protective circuit. A single wire, attached to the input terminal on the device, selrves as an extension to the sensor circuitry. Touching the bare wire at any point along its length will activate the control. The wire is attached to each +iling cabinet {at the points rnarked E) by using a sheet metal screw and a crimp-on terminal. Each of the cabinets thug become= an integral part of the sensor, touching any part of any cabinet will activate the alarm. Any metal object may be attached to the sensor wire, such as shelving units, racks, doors, doorknobs, window frames, bars, fences, screens, etc. Each metal object attached to the sensor wire becomes an estension of the sensor wire. Touching any of them will activate the alarrn.
58
b' THE SHUNT LOCK ====ttta=-E-!!-GEl!3-=_tlE_lEt!IMtlEtrtltt
rn the section on troNTRoLs, the detay timer was described as onE! means of departing from and- re-entering a premises when the alarm is
switched on without triggering it. Thi; describes another p'pular rnethod, called shunting the entrantresection door. The wsrd shunt neans cor'trcrr red by-pass! A shunt lock is nothing mclre than a key operated st'litch that enables the door sensor to be by-fassed from outside. A+
rl-
-.1
l-
The figure absve depicts a sens'r (A' connected into one leg of a pr,,tective circuitThe arrows represent the flow of superviscrry current through the closed switch, tA could be any type o{ senstrr, plunger, magnetic, motGilOetector, etc. l
Above, the sarne senssr is shown in the trpen condition, continuity, so the current cannot {low through it.
r
interrupting
qB
I
I
A'r I
I
Examine the above diagram closelyrt the sarne as the previous diagrams, with an important addition: A isis the sen5or, but a special type of snitch (B) has been imposed at c. open Note the wires of switch B are attached directly to the same terminals that that connect sens(]r A into the protective circuit. Also note that the supervisory current has followed the path of least resistance, try-passing ABefore going to the next revel of this expranation, think about the interaction of A'and B: r+ A is closed and B is open, then B cannot sElrvE! as a secondary path for the protective circuit current.
B represents a rock, nhich is a key-operated on/c,t,G switch, designed expressly -shurrt for ug;e with a burglar alarm system. hlhen the concept outlined above is understood, the pictorial diagram on the fotlowingexplanation, Page should clarify the function of a shunt lock without further 59
On the le{t is a magnetic sr*itch wired into a protective circuit in the normal tnannErrt r+ith a shunt lock connected to the same terminal scrElh,g. Betralrse a shunt lock is nothing but a key-operated switch' this may be bYmagnetic switch passed at will by simply inserting the proper key and rotating it to the riqht-- which closes the contactg within the sr+itch.
thunl tocl connacllon
Protactlvo
The first figure ahsve is an assembled ure shnws its parts: I ig the externally (cylinder.l 2 is the front washert' notice the mounting surface to prevent movement. ed sleeve, which couples with the cylinder. is a pair of terminals for attaching the the third figure.
shunt lock. The second figthreaded key-switch bodYt the spikes (31 which Pierce 4 is the internallY thread5 is the rBar washer. 6 connecting wiresr as seen in
En the right is a side-view INSIDE CUTSIDE cut-away shorring a shunt lock assembled through a 7/8" hole 20 bored through a door rail: is face. 2 the cylinder is 1 the front washer' 5 is the uPper piercing spike. 4 is the the body. 5 is cylinder sleeve, 6 is the rear washer. 7 is the the rear lug of the sleeve, which is flat on two DOOR EM sides to accomodate the jaws of a wrench when tightening the two sections together. B is a These wires pair of wires attached to the terminals o{ the cylinder. are passed through. a t/4" hole in the rear lug o{ the sleeve. NOTEI I'lost shunt lock sleeves are 2" long to accomodate freivy doors. The average residential door is 1-31Gl" to l-3/4" thick. one solution is to order a,shunt lock II I jf11-r, with a special "short sleever" or order f ive extra rear II Be certain that the -li--;-:-:t:jlH washers to -qhir up the dif{erence. II to make contact with the exposed terminals of the keyswitch-- f,|-Eey will be shorted, defeating the switch. 60
The figure on the left shows the most typical positioning of a shunt lock, (viewed from inside. ) Logically the device must be installed on the hinge-side of the door, =io a flexible cable (door cordl is used to carry the connection to the frarne. This enables door to be freely used with no strain on the the connection. A door cord is nrerely a +lexible, two_ conductor cable with a terminal block on each end- Each terminar brock has two terrninals and holes for mounting. Bne ='cr€'*!, end of the door cord is fastened near the shunt lock (A) and the wires fron the shunt lock are! con_ nected to it. The other end is fastened on the frame (B), a pair of wires are taken frorr it and connected directly to the terminals of the magnetic switch that rnonitors the door. Reviewino the operation of a shunt lockr A key is inserted into the shunt lock (outside the door), rotated to the right and removed. This closes a pair of internal contacts in the shunt lsck, enabling the protective circuit current to by_parg rnagnetic switch. The doolnay nou, be opened without triggering thethealarm. In ather words, the magnetic switch is neutralized by this action. t'Jhen departing from the premises-- after switching the system on-the key is inserted in the shunt lock and rotated to the left. This PEens the internal contacts, diserr gaging the by-pass. The magnetic switch is now fully active and will trigger the riarr if the door is
opened.
The advantage o{ a shunt lock is that no delay is imposed system's reaction to an attempted break-in
on
the
The disadvantage of a shunt lock is that it presents a skilled burglar with an opportunity for external tampering: I+ a shunt lock is to be.y=.91 do 4or! purchase one that u=;ErEi a flat, brass key with cutg on both sides- These are the least expensive types, but can be picked Epen very easily Hith a {ew strokes of a "rake,, type pick and a simple tensinn tool ! A shunt lock that uses a "tubular" (round) key offers a much higher level of security'. They cost a few dollars more but are well worth it. These locks are also Eusceptible to picking, but a special tocl and a hiqh level of skill is required to do it. -itris type of shunt lock is perfectly adequate for the average situation where a sophisticated attack is not anticipated. At the top af the line i= tnr highly pitrk rasistant shunt lock, which is recommended for any installation which qiqttt ccl,rlGl under attack by :. ski-llgd, professional burglar. These are designated as maximum srcurity devicis' and are Uf- appr;ved for burglar alarm use. The l.lEDEtrB(tm) shunt lock is very Eiecure. 6t
TROUBLEBHOOTIN6
the most comroon causes of "trouble" in a burglar alarm system no maintenancE, damaged componentsr adverse are careless installation, environment, routine wear and de{ective cornponentsr in that order. Among
loose or Careless installation includes poor rriring discipline, poorly improper fastened and connectictns, switches sloppy terminal placement or adjr-rstrnent of area protection devices, etc. Defective, rnalfunctioning components are frequently the result of buying burglar alarm equipment from sourcErs other than knowledgeable, specialized dealers; but even a professional-grade component can be damaged by unusual events, movement and traffic, or af#ected by its environment. Furniture roovers and window-washers are the rrorst enemies of a burglar alarm system. Next on the list of troublemakers is a greasy environinent, such as a busy kitchen, a gas station workshop, etc. Airborne grease accurnulateg on anything that ign't frequently cleaned, and it gets into the smallest cracks. I+ the grease cantains salt, the film it deposits is corrosive. Some components will just naturally wear out frorn routinEr Llse, such as; the switch t:n a heavily-used door. Pro{essional-grade sensors are test-rated at X operations betore anticipated failure, (several million operations, typically. ) By estimating the avGrrage daily traffic rate through a door and dividing that figure into the test-rating figure, the expected li{e span of the sensor may be projected. l*lost senscrrs will outlive their rated average-- but should not be expected to. A sensor attached to a door that is opened and ctosEil ZOO tirnes a day (amounting to 4OO separate operations) should last b-l/? years with a test rating of one million operatitrns. A switching sensor that isn't operated enough (at least Ence a day) will tend to get "la=y" from accumulations of corrosive film and stiffened springs. Using a switching sensor (a magnetic, for example) rrn a r+indow that is rarely opened is not rElcornrnended. A more straight*orward, non-rnechanical type of sensor should be used, such atr a wire lacing pattern, a laced frame, or a foil pattern with the protective circuit wired to take-off blocks. (Foil may be applied to walls as well as glass! ) If carefully installed and protected from damage, these "f ixed" sensors will sierve reliably for many years r+ithout attention. Any type of mechanical, switching sensor must be periodically operated to keep its contacts "wiped" clean and to exercise its springs. There are two common categories sf burglar alarm malfunction: operatjonaf and pre-aperationaf. An operational malfunction is a false activation (or failure to activate) while the system is armed. A preoperational malfunction is one that is discovered when the user tries to switch the system on and it won't set upt indicating a problem either in the protective circuit or in the control panel. 62
The first step in troubleshooting a pre-operational malfunction ig tt] make sl-lrE that all switching sensors are engaged (windows and doors -;;; are closed-) Next, set a test meter to read Oi volfnsE (at the voltage rating as the protective circuit battervl antapprv the ieter's probes to the protective circuit terrninals inside the'control panel. I+ the needle rnovErs ("reading" the battery) this indicates that the protective circuit is intact and the problem is either a qreak battery or it's sornewhere in the control panel. Brisk, energetir ro[6r,-o+ the needle is an indication that the battery is string, a laey, sluggish rnotion of the needle indicates a weak orEonversely, discharged battery.
A multimeter can test for the presence of electrical Elnclrgy, it can rneasure voltage levels, but it cannot accurately measure the and amount of stored Energy (amperage) remaiiG-g in a battery. only a battery tester (arnmeter) can do this. A fuliy discharged will often contain enough residual elnergy to excite the sensitivebattery coil o{ meter, but not enough to puII in the contacts of a protective circuit a relay. sot when the systery lcon't set upr but the protective circuit reads apply a freEh battery directly to the protective circuit "live," terminals i5 & a-in ttte control panel. ) I+ this doesn't f orce the systern to set uPr it proves that the problem is in the control panel. A simplel premium quality control panel (such as the.,lOO,) rarely rnalfunctions; if it does, the entire circuit board (control instrunrent) may be replaced by removing four strrehrs. (This is one advantage of using a simple control panel.) Returning tr: the initial step; i+ the meter needle doegn't move at all when atrtrlied to the terminal ends of the protective circuit, but ,nEves briskly when apPlied directly to the terminals of the battery, it Froves that the protective circuit is open at some poinil--TFilrs a sirnpler two-step procedure has isolaterd the problem to the protective circuit. Troubleshooting is a ioqical progression of stages, of which further isolates the problern and eventually will pin-point each it. Fig.?1-l (next page) shows a top-view of the perineter (outer wallsl of a rectangular, single-story commercial prernisEs, which is monitored by a 12 sensor systern. (trount these sensors before proceeding. ) The control panel is shown fastened to an interior wall, the bell wiring "snaked" through the wall to a bell mounted on thewith exterior. The dstted line represents a protective circuit pair, originating at the control panel and running in the direction of the arrows around all four walls of the premises. The two doors are designated D (for Dsor) I & 2' the windons are designated N (for Hindon) 1 thru B. Each sensor in the prolective circuit is designated S, (for Bensorl I thru 12. The protecti've circuit ends at the 3 volt battery'which is shown as a pair of circles in the lower left corner, marked * -.
51 is a rnagnetic switch monitoring the entrance door, which is Dl. a foil-pattern trn a window at bll. SiS is a laced screen fastened t:ver a ventilator duct in a toilet. 54 & 55 are'foil patterns on windows lJZ & ulS- 56 is a PIR {passive in{ra-red) motion detector, projecting its bearns down the length of a center corridorThe remainiiig-sensors monitor f ive rnore! windows and the rrar door. S? is
63
UIBRBTIOH
5le
CLTHTROL
OETECTOR
,PRNEL +
]fc'
t
k- BELL
Fig.2l-1.
'lt
+ TE
5s+
+ TA
T$
+
T9
Fig. 2l-2. of FiS' ?L'lr ghowing onlY the control Fig. 2t-2 is a simpli{icationcircuit wiringt with twelve sensors cclnpanel at A and the protective 64
nected in series and terminating at the batteryt B. In this hypothetical example, the bell reng when the systen r*as switched orr (a pre-operational malfunction. ) A visual inspection revealed no apparent causer so a service technician was called. The initial trouble-shooting step isolated the problem to the protective circuit. A direct reading at the battery terminals shows the battery to be futly charged, The next step is io tegt for a reading further along the protective circuit wiring, beginning voltage at Tl (for Test-point t) in Fig. ?t-2.
AE/P PHIP
FIN -.?
TII I STET] IJIFIE
Flg, 2l-S, The way to perfonn a meter test when ncl exposed terminars atrc€lssible is shown in Fig. 2t-3. l'lap pins (which are better for are this than ordinary straight pins) are pushed through the insulation of task the wirest making contact with the conductors beneath. The meter's probes are then applied to the pins. When aPplied at T1 the meter indicates live voltage, which means the circuit is intact between that point and the battery. This step is repeated at T? and again indicates voltage; likewise at TS, T4 and TS. lrlhen the meter is apptied at T6, however, the meter needle doesn't budger indicating that somewhere between that point and the last testpoint (TS) there is an oPen in the circuit. Between TS & is l,rlindow 4t which is monitored by a foil pattern, the most probableT6 location of the trouble.
Itl4 is a picture window, which is depicted in Fig, Zr-4 (next page.) To tegt the patternr the protective circuit connections are removed from the take-o*f blocks at A. The meter is set to read CSNTINUITy and its probes are applied to the terrninal screws of the take-off blocks. r+ the pattern is intact the needle rritl swing to the right.
In this example the meter showed that the foil pattern is open at point- Foil damage is sometimes visible scratch but just as often it is an invisible, hairlinea clearly crack that rnust he further isolated by probihg short spans with the meter. In order to penetrate the insulative varnish coat r*ithout having to gouge holes in the +oil, the meter probes must be needle sharp. The ideaf meter for burglar alarm work will have 36" leads with alligator clips at the ends iinstead of pointed tips) for probes. Eiripping map pins in the jaws of the alligator-clip probes, is the best way to test a foil strip. The meter at position I is reading to the rightr showing continuity between its probes. Likenise at positions z and s. At position 4 the sorne
65
needle doesn't move, indicating that the break is somewhere betwesn the
probes.
Fig. 2l-4. Now that the oFEln has been isolated to a relatively short section, and it still cannot be seen, a sequence of probing steps at l' increments will quickly locate it. Fig. ?l-5 depicts a short strip of foil with a crack in it. One of the meter probes is applied at A and the other probe is applied at l. Becauge the foil between these points is intactr the meter will show continuity. hlith one probe still +ixed at Ar the second probe is moved to point 2, then 3n then 4-- at which point the needle will not move! Thus an invisible, hairline crack in a 2OO foot protective ciFE[it, rehich contains numerous sensors (inclr-rding a sophisticated motion detector) has been isolated to a 1" area. This problem is easily corrected by stripping away a 2" section of foil with a razor blade and applying a patch. R
rt
e
Fig,2l-5. 66
'l
just as easily isolate a defective door The sarne procedure will switch, a torn conductort a broken strand o{ lacing wire in the frame over the ventilatcr ductr oF eny other problam in the protective circuit. Although thig explanation has been carried throlrgh exhaustive detail to illustrate the use of a meter, under actual circumstances the problem could be istrlated and repaired r+ithin a {ew minutes. In {act, this example hes taken the "long way home" to denonstrate the troubleshooting protrEdure: Referring ta Fig. 2l-2, the following explains a much faster way to find the problem. After determining that the protective circuit battery is good, instead of malcing the first test at T1, logic dictates that the best place to gtart would be at midpoint in the circuit, in the area of T6. For example, if the first test was made between Ei5 and 5i6, the absnnce of voltage would immediately show that the problern is somewhere between that point and the battEFyr thereby isolating the problern to 11ne protective half of the circuit. =peci{ic The next step is ts rnove back toward the battery (instead of away frsm itl r again dividing the remaining distance in half by testing between 59 and SlO. This time the test would show live voltage, indicating that the problem is somewhere between that point and 55. Again dividingt the next test nrould be between 57 and SB, where live voltage would show that the problem is between that paint and 55. Dividing the remaining distance would narroe* the search to approximately the area of T6. Thus the problem has been isolated to Si7 in only three steps irrstead of the six steps taken in the first explanati en. l+ the problem nas the rnagnetic sr*itch at Sln instead of the foil pattern at 57, eleven steps would be required to find it by taking the "long way home. " Fy dividingt that is starting at T6 and reading live voltage therer t:ne step would elirninate half the circuit; thus the prob1em would be located in just three or four steps, Live voltage at Tb wot-tld dictate that a test be made between Ei3 and 54, then between 51 and 52' Finallyn a dead reading betrreen Sl and the control panel would the problern is in the magnetic switch at 51. Dropping the =uggest that circuit protective connections frsm this sr+itchr applying the meter probes to its terrninals and operating the switch would reveal the problern. Replacing the switch r+ould solve it. The foregoing has described the sinrple, logical procedure involved in troubleshooting a corrs*ant rnalfunction, that is a problern r'rhich appears and remains constant. Host pre-operational malfunctions are constant, deriving irclm pfrysicaf darnage to a protective circuit component while the system was grritched o{{. As shown in the foregoing examplen a constant rnal{unction (torn or scratched foil} is relatively elasy to locate by moving a test meter along the protective circuit wiring in a logical progression sf steps and observing the meter'g needle. An operaticrnal malfunction is one that clctrurs while the system is in service, usually producing a false alarm. trccasi6ETly an operational malfunction will be the result of damage caused by an unugual event 67
such as r4ater leakage, rodents (whs like to chew wires), falling boxes ar shelves, etc. This kind of damage will produce a problem which is easily traced because it is constant, (a broken senscrr, scratched foil, a broken conductor, etc. ) Host frequently, howeverr Efi operational problem, often referred to as rnalfunction is cauFed by an interrittent statedr En intermittent problem is Ene a "swinger" or a "hider. " Simply rnornentarily, often causing the protective that appears spontaneously, and then restores itself. circuit relay to drop out--
problem is an irnperceptible (usually pattern at the base of a take-of{ block} which crack in a foil when the window-pane contractg from the during a winter night, otrcurs to flex with it. is too brittle The crack is barely csld and the foil current flow through wide enough to interrupt the the protective cir(and glass relaxes) the begins to rise the cuit. When the temperature protective restoring the circuit. As previously tiny crack closes, protective circuit the will not stop the bell {ron explained, restoring ringing, Eo unless a cut-off tirner ig used it wilT ring until someone arrives with the prciper key to turn it off. The classic example of an intermittent
specific problern is to leave a little One way to prevent this slack strip meets the take-of{ block (don't at the point where the foil stretch the foil tightly there) and apply a generrous amount of varnish at this point for added support. This point, incidentally, is usually subjected to darnage from a careless window washer's squeegee. So in patterns situations where commercial window waghers are used, foil should be considered a prime suspect, especially i+ an intermittent problem arises shortly after the window*washer has been around, trheap or worn-out sense:rs can trause intermittent probl€rfns; so can loose or corroded splices, loose or corroded terminal connections and damaged protective circuit wiring. The fact that msst false alarmg occur in the middle of the night (most often in wintilna during thunderstorrns) directly implies the contributing factors o{ temperature change and vibration. The rnost e{fective approach to locating arr intermittent problem is a physical "shakedown" of the protective circuit: The system is switched on and, beginning at the control panel, the protective circuit wiring is tugged at and prodded, especially at corners and splicesr and in the area of each staple. Sensors should be tapped nith a screwdriver hanor a rubber hammer. dle and the surrounding areas pounded with a fist The type of foil crack degcribed above can sometimes be found by poking around at the take-o{{ block with a finger, but the best way to test foil for a "hiding" crack is by spraying a film of aerosol frost directly onto the foiJ-- concentrating on the base of each take-off block and on patches. (A carelessly applied patch hag a high potential for problEr,ns. ) Aerosol frost is available from eleccausing intermittent tronics suppliers, it is commonly used to coax out invisible cracks on printed circuit boards,
Nine out of evErry ten swingers can be located by a good shakedown of the protective circuit, which includes a careful visual inspection of the circuit while tugging, tapping and pounding its components. Screw terrninal connections should be lot:sened and re-tightened, eEpecially in 68
a damp Br greasy envirgnment, hecause grease and corrosion can accumr!late under these screws and produtre an insulating filrn. lllhen shaking down a protective circuit, remember that Erv6ln a brandnewt mechanically perfect magnetic switch can be disturbed by a heavy blsw. The feef o{ just how hard to tap a rnagnetic switch during a shakedown may be developed only through experiment and practice, Obviouslyt vibration detectors cannot be tested by this "shakedown,, proceduret scl they nust be jumFered out of circuit be{ore proceeding. hlhenever a vibration dectector is in use' it sheuld be regarded as a probable trause of an intermittent problem. I+ a better "suspect" cannot be located, all vibration detectors should be temporarily removed-trr their sensitivity adjusted to rninimum to see if this solves the problern. The same reasoning applies to any type of motion detector: I+ a rnore apparent cause o{ an intermittent problem cannot he found, these devices should likewise be suspected and adjugted to low gensitivity, or temporarily jumpered out a* circuit. Just because a system false alarms once, after a long period of stable operation, does not mean there is a swinger in the circuit. The mt}st stablet trouble-free system can be subjected to an uncommon event such at a severe, localized tremorr irn unusually loud or high frequency noiser BF the spontaneous discharge of atmospheric static. llthile an attempt should be made to locate the cause sf any operational mal{unction, an interrnittent problern is one that rfcurs. Sometimes it will atrpear r"lithin a few hours after the system-iE-Ewitched on and sometimes the interval between aFpearances will be several days. In either c5rse, there usually is some corresponding cause. In one example, a system that contained a nurnber o{ vibratisn detectsrs began to {alse alarm trn l"londay nights only. This system nas thoroughly inspected (r.lhich included tno vigorous Ehakedowns) but no caug;e was fsund- The fact that it happened only on t"tonday nights suggested an external, corresponding callse. A long-duration tape recorder {with a Fre-amplified microphone) was situated on the premises and syritched on at closing time. Flaying back the tape after the fourth, ctrnsetrutive Bctrurrence revealed the cause: The l,londay night (relief ) barmaid in an adjoining tavern liked rock music and ran the juke-box up to full volume after the place began to empty, at about l!O{r Atl. The juke-box speakers htere mounted on a r.lalI that was continuous with an adjoining wall in the protected prernises, which was monitared by vibration detectors. The problem was solved by replacing the vibration detectors with a PIFI motion detector. Long-duration tape recorders are an efficient means of deterrnining the cause of suctt probl€ltns. In this case, the sound of a throbbint bass guitar was heard on the tape immediately before the alarn bell started ringing. The foregoing is an example of a cofltmcln audio-surveillance technique applied to a very legitimate purpose. The same technique has been used to identify villains as whistling rad?!ch trouble-causing iator valves, timer-activated heating systems, banging steam fripr=, ringing telephones and, in one instance, the nsise of a garbage truck's 69
hydrar-rlic hopper at 5 Al't, All of these things, and quite a few rnore, aFE caFable of disturbing motion detectorg and hypersensitive vibration is one way to discover such detectors. The tape retrorder trick mysterious events. (Long-duration tape recorderg and ampli{ied microphones are available from gecurity & surveillance equipment suppliers.) blhen no arnount of probing, prodding, tugging, pounding or Sherlock Holmes-type deduction succeeds in ferreting out the cause of a swinger, the process of elimination is the least desirable but mast positive way to get rid of the problem. I+ e system consists of rfiany sensors the elimination prtrcrss can take several days, during which time the system alarms until the problen is rRr-rst be shut down to avoid repeated false el i mi nated: One nay to proceed ig to rernove the bell cnnnection from the control panel terminals and attach an indicator lamp trated at 6 voltslin its (remembering place, then disconnect hal{ of the sensors in the circuit, to clip or twist the vacated protective circuit wires together to close the circuit. ) If the problem does not recur, which is determined by oblamp upon opening the prenises each day, begin serving the indicatsr replacing the components onr at e time until it does. hlhen the problem recurs, the last component replaced is probably the cause and should be changed.
I+ the intermittent does recur while half of the components are disconnected, begin removing the remaining cotnponents one at a time until the problem stops. lrlhen it stops, the last compclnent removed should be changed. Then replace all components and return the system to service. Rarely will a simple, professional grade contrsl panel be the cause o{ an intermittent problem, but when the process of elimination doesn't wsrk the panel must be tegted. One way to do this (after the bell connection is replaced with an indicator lamp to avoid disturbing the neighbors) i= to drop the protective circuit connections from the control panel, attach the battery directly to the protective circuit termI+ it does, the panel is inals and wait to see if the lamp lights. obvior-rsly defective, Another nay to check out a suEpect control panel is to just EhraF it fsr another and see what happens. Batteries are strmetimes the cause of an interrnittent problem: l"{ost batteries will discharge at an even, predictable rate with an average service life of r:ne yErar, but a defective battery will sometimes disdropping well below the minimum service level then charge erratically, resurging to full power. Another potential battery problem is a broken carbon rod, r+hich is an extension o{ the positive terninal on a carbon./ This br-ittle rod extends through the center of the cell and zinc cell, is sometimes cracked by rough handling. Like a latent crack in a foil pattern, temperature changes will af$ect it. hlhen the crack opens, the l'toigture and temperature extremes will alss cell will become erratic. af{ect batteries, By follor*ing the principles outlined in the foregoing pages any type of problem in any burglar alarm system can be pinpointed and corrected. Ey now it should be clear that trouble-shooting is a logical process of The first step in learning the procedure is to obtain a elimination. 70
b. tuitable test meter and learn how to use it-- which takes about ten minutes' Once the meter, itself, is understood, applying it to a protective circuit is incredibly sirnple. Special rneters are available r.lhich are designed expressly {or troubl e-shooti ng a hr-rrgl ar al arrn system. One such i nstrument t "peter 's Heterr" degcribed elsewhere) provides LED indicators and an audible tone in additisn to a movable needle, thr:g it may be observed from a distance while shaking down a system to locate a gwinger. A set t:f clip-on test leads tjumperg) r which are short lengths of insulated wire with alligator clips at each end, comes in handy ior bypassing segments of a protective circuit, or individual sensors, when testing for an intermittent by eliminating trorrponents, The clips are =imply attached to both terminals of the sensor to be by-passed, Host interrnittent preblems are the result of careless installation practices and therefore are avoidable. trlhen a staple is shot through a conductor {instead af around it), in time the f ine copper strailGl;ithin r,ri I I become corroded and f ai I . Spl iced joints, which were twisted t+ith grimy fingers and nrapped loosely with tape, will eventually corrode and fail. One major cause o{ intermittents are spliced connections in a bell cabinet that are twisted and taped without first being soldefed. Focd wiring discipline calls for soldering all splices, but rrany installers are delinquent in this arEla, Failing to solder on interior wiring significantly increases the possibility of =pii.== future problerfis' but failing to solder the splices in a betl cabinetn where they are exposed to meisture and temperature extra;esr-IE-Eilning for trouble. A portahle soldering iron makes the job of soldering a very simplE! oner scr there ig no reason to ignore this important=pii.=, task. Experienced trouhle-shooters know that the JrttJe ttrrngsn like a lsose terminal screwr in un-scrldered splice, a little too much gap between the two parts of a magnetic switch, etc., are tlie things that causs the higgest headaches. The phrase rliring disciplirte is not loosely applied: Running wire, attaching sensors and aptrlying foil can be tedioug work, so it is often tempting ta ignore a little detail here and there. Ey selecting top-quality components and installing thern care{ully it is possible ts produce a systern that will perfarm for rnany yeers without the slightest problern. hlhen an intermittent problem is traced to a motion detector, is possible that the device is being triggered for a brief instant byitsome rnomentary disturbance such as discharger ;rn unusual vibration, noiser oF a gust of wind blowing=tatic under a docrr, Such events are capable trf causing e motion detector to activate for a split second, which is roorE than enough'time to "drap sut" the protective circuit reiry. This actisn tnay ssmetimeg be observed by sitting quietly in a rogrn nhere a motisn detectsr is operating and observing the walk-test light: Usually a slight rnovement of a hand or foot will cause the device to activate fsr a moment (causing the r.lalk-test light ts yrink on and off very briefly. This is not the normal action of a mation detectsr when it is sen=ing the massT'+ a whole human body movinq within its field. The difference may he seien by simply walking a few steps instead of 71
just moving an arrn or leg: The walk-test light will trornEr on and stay on fcrr at least three crr four seconds, depending on the speed and distance covered. A motion detector which is activated by an actual bodily rnovement will activate and maintain its active state for several seconds.
The foregoing implies that a slomer protective circuit would solve Ey slightly "retarding" the the problern-- and in most cases it will. nornally instantanslous drop-out action of the protective circuit relayt ignore a momentary interruption in current flow, a so that it will false alarrn-prone systetn may be stabilized. The drop-out speed of the protective circuit relay may be retarded by attaching a simple, gemi-conductor component to the protective circuit terminals (5 & 6, inside the control panel as shswn in the figures below.
TUBULftR ELEETROLYTIC CAFfiCITON
capacitor with axial leads, (a The device is a tubular, electrolytic small, cylindrical obje,ct with a lrire gticking out of each end. ) The wires are bent as shown and simply fastened underneath the ser$e The function o{ a terminal screws that hold the protective circuit. capacitor is ts store a specific amount of Ernergy, much like a battery, and discharge it slowly when the parent energy source is removed. COHTNOL FRHEL TEFNIHRL STNIP - SHOIIIHG HONilRL CO]IHECTIOHE IIITH 8SI UF CFPNCITON NDDED TO INPOSE fi IIELfiY
IH
PNOTECTIUE CIRCUIT RELfiY DROF-OUT
TIIIE.
The capacitor absorbs a tiny amount of energy from the protective circuit battery. l,lhen the protective circuit current is interruptedt instead of the relay dropping out instantly as it nornally wouldn the tiny amount of energy stored in the capacitor wil.l maintain the relay The exact number of seconds until that stored energy "bleeds off." 72
b,n" thrs takes ithe delay peritld) depends on the rating o{ the capacitor. These capacitors are available at electronic supply rn a wide variety of ratings' capacitors are rated in fractionsstores of a farad (a unit of measurementi called rtcrcr-farads, (one millionth of a farad,) l-he syrnbol for micro is the character u, the symbol for farad is f ; thlrs the markingn 6l)(lt-t+r oFl the body o{ a capacitor means 60(r nicro{arads' which will provide approximateiy ? seconds o{ deray. Another rnarking on the capacitor indicates its polrrity, and it ig rrnportant that nire on the + side of the capacrtor be attached to the same terrninal as the + side of the protective circuit-sr 'lhe it work' polarity marking will either show as a + srgn at one won,t end of the device or an arFc,H pointrng toward one end, indicating the Fositive {+, end. Ihe ob jective s{ this sectisn is problern in a burgrar alarm sv=tern eliminationFor example, the bell the belI circr-rit cgnnection at the these wires to a 6 volt hattery. If entire beil circuit is intact. Eut panel is activated, the problern is probably the bell relay.
ts is
ttiat f inding type of simplv a process ill-y_ of gradual rnay be tested hv simply dropprng control panel end directly applying tn* bell rings, this means the if it won't ring when the control obviously in the contror panel-shourr
Ey drepping the protective circuit connections at the control panel and directly attaching a 3 volt battery to the vacated terminals, the control paner may be tested wi_tr-rgg!
a protective circuit. Eecaltse sq ' 92 of al I probl erns otrtrur somewhere i n the protecti ve circuit' trornmBn sense dictates that this sheuld be tested first. r+ the meter does not read voltage,frErn the;f volt battery when its probes are applied at the contrsl paner end, go directly to the battery and apply the meter to the battery terrnirr"i=. r+ the battery is okay, rrove further alang the protective circuit and take another readrng. f;eep moving until the meter stops reading voltage, then rrrrve back tin shorrer step=) roward the point Ll_yg readrns was tal':en' In thrs tnanner the proLtem will;;;; be in"-i"ll isslated to within a few feet' {or inches') Eegin disconnecting every sensor twithin the isolated area) trsm the protective circuit and test each one for contin!l-i!y and proper operatron- r+ all of the sensors see,n to--ul--f;n;;, check all splrces in the sarne erEra.
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73
INSTALLATION NOTES
is to evaluate the vulThe first step in planning an installation nerable points of a premises to determine which type of Eensor is nogt spprapriate fsr each point. If there are simply too many individual points to rnonitor in a given arear rrF the physical environment is somethen csnsider an area how opposed to the wiring o{ a perimeter circuit, protection device. Also censider the merits of using area protection devices in addition to a perimeter circuit. to select the best locations for the control panel and annunciatortg). Eefere deciding these locati{f,ns, all rriring routes must be carefully considered. Sometimes the rnost convenient or desirable loce:tions ft:r the control panel and annunciatsrtsi will impose in bringing the bell and pratective circuit wiring special difficulties ts thern. Keep i n rni nd that the bel I ci rcui t wi ri ng murt be total I y concealed frsm view or securely armored to prntect it from being cut. The next step is
The best location {or exterior annunciatsrs is anynhere that is not accessible without a ladder and affords a secure, concealed routs for wiring to the control panel. The best running the bell circuit location for the control panel is sonewhere that affords reasonably convenietrt access by the user and concealment from general view. If a power =upply is to be used (instead of dry-cell batteriesi, access to AC power is important. Whether a single.eorre or a multiple-zone control panel is to be used, the control panel must be located where it is acce=sible to the protective circuit (s) wiring, After weighing the circumstances of foregoing factr:rs and requirements, the individual each individual job should dictate the priorities, Except {nr high-risk situation=, where sophisticated tampering and protective circuit wiring need bypass attempts are a real pos=ibility, ncrt be concealed, So unless hidden wiring is absolutely necessary for protectitrn frsm tampering,, crr simply {or aFpearances, semi-concealed,
-qurface uiring af f ords a signif icant trouble-shooting advantage, hlhen and repairing a a protective circuit is tstally concealed, isolating problem which is'hidden inside a rrall can be a tough job. That thought sheuld prevail throughsurt any contrealed wiring joh and inspire close attention to proper wiring discipline. looks better, and a{fords prohrhife a fully concealed installation tectir:n frorn tampering and physical damagen it calls for a significantly greater amount of patient, careful work. Laber is the biggest f actor in the f inal cost of a cornrn€]rcial ly instal led burglar alarm: the cost r:f a concealed wire installati-on is usually triple the cost of the with serni-csncealed niring. same installation by ordinary telephone wiringt typified which is generally stapled along baseboards, up and ov€ir door-frames and moldirrgsf etc., and passed from room-to-rootn through small holes dritled in trorners. lrlhenever a closet can be exploited as a "tunnel" to another levelr or a shortcut between rt:orns;, it is. trlhenever the wiring can be tucked behind a loosened baseboard, it is- hlherever wire can be csncealed without major wsrk and reconstructiont it is. SemiSemi-crrncealed r.liring is
74'
concealed wiring is taken through snall holes drilted in the side or bottnm of kitchen rabinets, then through a wall or up through the ceili ng , i nto an r-rpstai rs cl oset , etc.
Frstective circuit wire, which is little different from telephone wirer can be hidden behind furniture and stapled into the edge= .igngside wall-to-wall carpeting, 5 volts is very lsw-voltage so there is littfe risk o{ a protective circuit starting a fire. High (hazardous} voltage is rated at 4O volts and above by most electrical standards, but a staple that pierces the insulation of a pair, causing a dead sficrrt acrt:ss the protective circuit, will radiate a hiqh tempirature a5, it rapidly drains the battery. In a hot, dusty environnent, such a5, an attict special care must be taken when stapting wire. Stapling r.lire is a simple procedure but a beginner should practice stapling a few 6 {t' lengths of ??/2 la a lumber scrap be{ore starting a first jt:bt because it takes a few minutes to get used to the proper feej sf the staplegun. Regardless of how profiiient one becomes this tool r every staple should be closely observed in good light towith be sure that the legs of the staple straddle both legs of the pair and haven'.t punctured either teg. The first staple is the anchor, from there each successive, lB', length of wire is stretched tight before the next staple is shot. The nsse of the Arrow T-18 staplegun (the standard of the trade) is grooved tt: accept a 2?/2 tt*isted pairr sB the gun is slid down the wire as it is worked into positionr pressed down tightly and snapped. Before shooting the staple, look to make sure that the groove is straddling bCIth wire legs. After shooting the staple, regardless o{ hor* good it felt to the hand, look again to make surEl. This is good wirinq JiscipIine and prevents a great deal of future trouble. Staple pun.iures poorly crafted spliceg arE! a major cause of intermittent problErms. and An unsoldered splice is alright fsr a temporary situation (a year or sEr for exarnple) but it cannot be depended on a{ter that time. A staple puncture is certain to cause a problem in the future. Baseboards and corner motdings tran usually be pried array to accg'rngdate a 2?/2 pair but they must be replaced carefully, naking sure the pair is not crushed in the trorners, Never withdraw the finishing nails all the way because they must serve as guides for the wires as the melding Br basebsard is being replaced. Dropped ceilings and acoustical tile ceilings are ideal wiring conduits because they often are common to numerous rooms within the same premises. Attics and cellars are another way to rnovEr niring {rom one area to anolher. By drilting up through closet ceilings oi do*r, through coFners in a flosrr wiring can easily be taken from one end of a premises ts another. hlhen it is not practical or possible to hide wiring behind baseboards and moldings, in closets and cabinets, attics, celiars, etc., it may be stapled along the top of baseboards and alongside moldings. If it becornes necessary to run a length of wiring straigfrt up a wali tnitf, no concealment) and this looks unsightly, there aie. several types of decorative "Facee{ay" available to make a neat job of it. hliring 75
--=
lengths of low-profilet plastic ctr fastened to a waII surface. The to clips attach metal conduits that size and a variety of corner sE!cright to the ratrepay is easity cut hliring ratreelay is appearance. a {inished to create tiens are available and electrical hardware, centers, available at most do-it-yourself and to work with easy very is inexpensive, It lighting supplierg. wiring' surface to ePpEarance inrparts a very neat Snaking wire inside walls is an intimidating prospect to anyone who experieince at workhas never done it, especially to one who has tittle procedure involves removing the treset sorne In ing with wiring tools. plasterr Fulling punching in paneling, holes of wall entire sections through the 2 x 4 "Ertrssholes boring and out bunches o{ insulation methodg These require Ee:nstructior.. wcod-freme in cets,, and "headers" platrElt wiring is in the work after finishing skilled reconstruction and planning routeswiring when which must be considered "raEeway" is usually sold in 6 ft.
EELLffR
Fig. 22 -l . The figure above reipresents the wiring routes o{ a residential inThe control panel (shown at A) is situated in the entrance stallation. The bell is mounted under the eaves at B. The dotted line corridor. (C) represents the bell circuit. A is mounted on a r*all in the corridor closet. It is a two-zone control panel with a built-in ptrrler supply and entry/exit delay. Directly over the closet where A is located is an upstairs bathroom. Ey removing the medicine cabinet and drilling a ltr hole down through a a "cross Eat" (a horizontal 2 x 4 used in fraatework) t and drilling larger hole in the closet wall, it is easy to srrake the wires up from the closet to the medicine cabinet, which is located at C. By drilling 76
up through another cross-cat, the wiring ]tas passed up {rom there to the attic and taken directly tE the bell location, at B. An ejectrician'-s srrake can be purchased at any wel l-stocked hardware store. This is a ?4 ft' (or longer) coil o{ tempered steel r"lire, 3/16" wide by lllb" thick. From thisr sevElral shorter lengths are cut, z ft. 3 +t. 4r 5 and 6 ft. These five lengths are usually adequate for ' jabst r except rnost where wiring must be pulled through an extremely long conduit. Using the jaws of the same sjde-cutfer pliers that hrere used ts cut the heavy wire, a narrow,3/4u hook is bent into one end of the shorter snakes. The figure on the left shor*s the typical use of a short snake, which is shonn at B. Note the short hook at one end and a larger loop at the gripping end. In this diagram the snake will be pushed through a small hole drilled through a wall in a baseboard corner (Cl, end used to "fish" for the length of heavy bead chain which is shown lowered from a hole drilled through the opposite side, at A. A 20' length of bead chain (stored on an empty wire spool) comes in very handy for situations like this, because it's sometirnes di++icult to bend a snaking wire at a critical angle- After the bead-chain is hooked and pulled through at C, the wiring will be fastened to the end of the chain at A and will follow it when the chain is pullled through the rrall.
Another handy wiring tool is an ordinaF1r' tubular aluminum r .ZZ rifle-cleaning rod. A notch can be cut or ground out o.f one side o{ the patch loop (o{ the right size {or snaggr,rg bead chain and 22 gauge wire. ) These rods are sectional and an unlimited number Fig. ZZ -2 r
of sections rnay be joined together for reaching through long, t'cragtl spaces, " etc.
attic
In
Fig. ?? -1 t the fine, solid lines represent protective circuit The wires of zone 1 are pulled up into the attic along with the bell circuit. At L-l and L-Z (for Loop t and Loop 21, this circuit is pulled through a closet ceiling, where a separate loop is connected into it. Zone 1 is taken right to the bell connection, where the tamper switctt. loop is connected to it, (not shown. ) zorres I and 2.
Zane ?t tE) is passed down {rom the closet at A into the cellar. In nogt caseg the plurnbing from the upstairs bathroom would be {ound in this patht which sometimes provides a ready-made conduit to follow. Eare must be taken whenever drilling into a wall where plumbing pipes and high voltage wiring are likely to be hiding. To be on the safe sider use a 3/E}" or t/7" chuck, heavy-duty, variable speed, rclvElrsible drill because they are easier to control. Bore slowly untii ttre tlp 77
breaks through to the hollob, sFace behind the wall, then stop. tlithpush the tip of a screwdriver in, tap and feel around draw the bit, with it. hlarningr Never drill into g wall with an un-grounded drill ! Zone 2 is brought up through the floor inside a kitchen cabinet at LI, where the kitchen loop is connected into it, at L-3. It then eccomodates the living roorn loop at L-4 and finishes up at the cellar loop, (not shown. )
Note that one of these two zones makes an "appearance" in every rtrom In the satne way that an unlimited nutnof the hause and at all levels. ber o{ senstrrs may be added to any separate loopr eny number of loops future expansion of the system ig may be added to these two zsnes i{ desired. These arE! the prirnary wiring routes mentioned in THE EASItr EURELAR ALARH SYSTEH and they should impart a general idea of how to "lay Eut" a system.
This example does not imply any rules, it simply suggests sorne of the tricks of the trade useful to snaking wire. Sometimes the only way to run concealed wiring is to break through plaster, cut out panels of drywall, tear up wallpaper and, sometirnes, remove door frames. These are radical methods and should be avoided whenerver possible.
--.5.
*iffii*
Fig. 22-3. Fig. shows an example of protective circuit wiring stapled "2-3 along baseboards, up and over lrindow and door moldings. In most situations the vertical lengths of"wire sEren running up a bare wall to a windorr frame would be concealed by drapes, along lrith the sensorg and ??/2 is available in their tronnections into the protective circuit. either brown or ivory color so it usualty blendg well with the color of a baseboard, especially when it's been painted ovErr. Furnishings normally hide a good percentage of the baseboard wiring, Ieaving only the 78
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wiring aroLrnd the door frame conspicuously exposed. The r+iring shor+n in Fig. ??-J may be totally concealed, but ing on the physical congtruction of the premises, the amount of dependional r*orl'; involved could be considerable. Sonretimes the hollow additspace in=ide the walls is accessible from an attic or cellar, which rnakes the job of snaking wire rnuch easier. I+ not, it might be necessary to pull out sectiong of paneling, punch holes in plastei walls, etc. As mentioned previously, the average handyman-for-hire is extremely conpetent at this type of work and r+ould charge considerably 1ess than a prcl{essicrnal electrician or alarm installer to do it. Assume that the cost t:f trcrrrpt:nents for an alarm system is 35(r.OO and the cost of having a surface-wired or semi-concealed installation done by a contractcr is 1'5OO.OO, the job will cost ITBEO.OO. The job with fully concealed wiring rnight cost two to three thousand same dollars Fut i+ a local handyman is hired to do nothing rnorEr than snakemore! the wiring through the walls, leaving an exposed ,'appearance,, near every windsw and dor:r, the cost of his labor might be bbo.oo to 1rooo.oo. l"lany independent burglar alarm installers operate in exactly thiEi mannerr using local handymen es sub-contractors, finishing the job themselves (which amounts to fastening and connecting the o{f to the exposed appearances) and walking away ruith a lr5oo.oo tosensors 2r5oo.oo profit !
Surprisingly, in spite of the fact that most local handymen are Erxtremely skillful at carpentry, rnascrnry, high-voltage wiring, etc., few sf them have tnrf,re than a general idea of hsw a buiglar aiarm w(f,rks. It ign't necessary to explain anything rnore tn"r, where to system the expesed apPearance.s. After the concealeO wiring is in place,leave and the handyrnan is paid off and gone, the control panel, U=fl and =iensors are installed. This completes the installation.
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79
SPECIAL TOOLST PARTS AND TECHNItrUES g3-EEaE=====3--:E4
t==!E-===E====-=----=a==E====--==
components' The foregoing sections describe a variety o{ specialized electronic an in together explaining how they interact when connected assemble to ea!3y relatively is hJhile it system called a burglar alarm. sePareach how (as understanding to an aid a working systern on a bench of task physical the iFstalling ate cornponent functions in the systern), proper the of herp the with simplified greatly be will co{nponents these tool s. (by trorresFonding letter) to the The following descriptions refer tot:ls shown on the next Pagel
BIT (or) BELL HANEER BIT: Thege A> FEELER EIT (or) ELEtrTRICIAN,s ?4" and 4E}" lengths; t/4" and lB", bits are available in 1?", drill drilling FaEisage holes through for 3/8,' diarneters. They ar€! excellent baseboardsn floors sheet-rock), hollow walls (p1aster, Plasterboard, into hollow reaching for useful are The longer ones and ceilings, wallstgdrillthrough2x4crosgcatgandheader=. of lengths, from 4" to 24" and B> l,lAsoNRY BIT: Available in a variety bits to use for drilling inthe are diameters frsm 3/L6" to 1". These cementt tile and plasconcrete, brick, to any type of fnasonry, such as {or drilling metal}t (those made are which ter. Never use,,twist" bits will be ruined inthey (including plaster) or on any kind of rnasonry brick, cement or as such masonry, through thick lrlhen drilling stantly. and stall' shriek to begins bit cement block walls, ind the masonry to lubricoil use Never water. of r*ithdraw it and dip it into a cup ate or cool a masonrY bit. * 6 - g (x 7/8" tr> PLASTItr ANtrHBR: These trome in several * sizes: which are a L/4" hole and will accomr:date 6 - B screg|st long) fits Lz (x 1") * 10 objects' small used to fasten sens,Err and similarly to mount bells, sirens and accomodates *lo - 12 screws, which are used(masonry) mounting surfatres' solid on csntrol cabinets. These are used L/8" (diameter) x 4" D> TOEGLE FOLT: Available in several xsizes: 4". used for mounting heavy 4"| !/4" (length), 3/!6- x 3"I 5/16'x hollsw plaster, plasteras such (]bjects on thin mounting surface=, board, sheet-rock, paneling, etc. The to991e slips through a drilled hole'snapsoPenandgriPs+irmlywhentheboltigtightened. of sizes' An alternative to E> I'loLLY ANCHBRS:' Available in a variety the toggle bolt. A ribbed sleeve that surrounds the bolt expands as the bolt is tightened. of widthsr from s/4" to 2-l/2"' F> HtrLE SAhl: Availabte in a varietywallboard, etc. trarbide version is panel, used to bore holes in wood, etc' available for boring metal. usea for shunt lock installationt of sizes. The smallest gize is B> SPADE TON6UE: Available in variety 9/4i4*, r*hich accomodates 22 - 1€l gauge wire. (Perfect size {or burglar
B
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WW
alarm work.
)
The split btade of this screr*driver exinside a screw index, holding the screw firrnly. This tool is particularly handy when working with window foil take-o{f blocks. Also useful for handling screws in tight working sPacesr EF when working fron a ladder, I> StrREtrt STARTERI Similar to a screwdriverr br-rt the tip is a hardenedr threaded strrew, (instead of a Ecrew-driving edge. ) Very useful {or starting screw-hsles with one hand, An extremely handy tool.
H>
EUII{-WEDEE StrREbIDRIVER:
pands to grip tightly
J> SIDE-CUTTER PLIERS (or) LINEi'|AN'5 PLIERS: Useful fsr cutting Er forming snakeg, cutting heavier wire (16 gauge zip cordl etc.), and such tasks as rerroving the "knockout" slugs from the back of bell and control panel cabinetsr etc. K> |{IRE STRIPFERI The perfect tool 'For working witln ?,212 wire. Easily adjusted to accornodate any size r+ire. truts and strips wire very quickly. The stripper groove is screw adjustable to any wire gauge. L> CORDLESS SBLDEFINE IRON: Eontains rechargable battery, Sold with Eharges up overnight. Full charge will accornodate charger stand. Extremely handy for soldering splices' esPecabout 5O solder joints. ially the splices in a bell box. tl> ARRObI T-19 STAFLE-EUN: The standard fastening tool for burglar alarm (and telephone) wire. The only alternativeg to using this tool are wiring tacks and the type of wiring staples that must be pounded in r*ith a tack-hammer. N> 6 VOLT LANTERN EATTEFY: (Heavy-duty. ) Used for powering bells & sirens. Lif'e-span is about one year (with no prolonged "ring-offs.") O> 1.5 VBLT IGNITION CELL: Two of these, connetrted together by jumpering the Positive terminal of one to the Negative terminal of anothert produces a 3 volt battery. Used to provide "supervisory" current fsr protective circuitg. Life-span is one year. P> I"IULTIIIETER (or) V-O-tl (or) I'IETER: This is a standard electrical testing instrument and is indispenEable when working with hurglar alarms. Eurglar alarm supptierg sell meters which are spetrially modified for the trade. B> "FETER's l"lETERl': (Named f or its inventor, who designed it specifically for the burglar alarm trade. ) Has several unique features that make the job of testing for an internrittent much easier, Two of thege features are an audible tone and an indicator light, in addition to the meter #ace. Another feature is a special circuit that sets uP and holds (just like a protective circuit relay), then indicates ("drops out") when the swinger "appears" during a shakedown. Recommended for anybody who intends to work with burglar alarms as a sideliner crr a 1 iving.
To avoid several trips up and down a ladder when mounting a bell, trece the mounting holes on a sheet of stiff cardboard to use! as a templateTie a le'ngth of wire tr: the bell cabinet and climb the ladder with the template, a drill, and the hoisting wire end, Use the template ts merk the msunting holes, drill the holes, then hoist the bell & cabirret up by the wire.
Set a srnall level on top of or inside a control panel when marking the msunting hsleg. It's hard to square off the box while holding it against a wall, and even a t/4. titt is unsiqhtly. hlhen it'g convenient to run protective circuit wiring under a walltcr-r+all carpetr sPlice in a section o# 22 gauge speaker wire for that purpose' This nirer called "72/2 paraIIeIr" is nuch thinner and won't shor+ thror-rgh as will 27/? twisted. When drilling through a hollow wall and you don't knors where the bit will ernerge on the other side, LrsEi a side-cutter pliers to cut a short gection of wire coat-hangtrr with a sharpl angle at one end. Chuck the other end in a high-speed drill (2r2OO rpm) and apply moderate pressure trr drill through with this improvised "bit." It bores a very small holer which tnay easily be patched with a dab of filler (Spackie, DaF, Plastic lrlclod, etc, ) i+ it breaks through in the hrong place. After mounting a bell (crr siren) and splicing the connections, apply a genercrus coating of RTV tRoom Ternperature Vulcanizing) cement to the tamper switch strrew terminals. This stuff forms a rubbery skin overnight which will protect against corrosion for many years. RTV comes in a tube and is available at any hardhtare store. lrJhen drilling a passage hole in a brick or stone wall for the bell circuit wiring, drill the hole at a slight angle (airning upward from autsidet or downward from inside) to prevent rain-water from seeping in through the hole. Also, block the hote with RTV.
Whenever wiring is to be concealed inside a rrallr oF anyrrhere that will be difficult to accesg and repair it after the wall is sealed, run an extra pair (spare) alongside it to be used as a substitute if a future problern develops. Four conductor cable, such as telephone wire, is recommended ft:r this aptrlication. Eonceal the tails of the spare pair in st]rne cr:nvenient place, to be retrieved and used if ever needed, Figure 3S-1 (next page) shows trne way to produce a strong splice: A represents t*re ends of two 22 gauge utires. 3/4" of insulation has been striptred away and the exposed wire strands twisted into rigid posts.
E shows the two posts twisted together; (apply a film of golder to these joined posts befsre prcrceeding to the next step, ) C shows the soldered joint bent backs.lard at its base and pressed tightly against one section of wire. 83
D shows t he finished jt:int el ectri cal t aP e.
covered with about three turns of plastic
..f-----it
R
B
Figure 25-l \ E
\ \ \ Figurr 2S-? two pairs of wires together! prepare the ends ag ghown at E, in Fig 23-?: Note that the stripped ends of the legs to be joined are offmt from each other. Thig is to eliminate the possibility of a loose strand of wire from one leg corning in contact with the other leg (and causing a shsrt. ) This also enables a much neatert finished wrap when the two legs are ready to be bound together, (see F. ) If the individually wrapped jointg are taped side by sider iD unsightly bulge wilt result when the two legs are bound together. practice to get but it takes a little Soldering is not difficult, (with plug-in an extension cord) iron used to: Use either a 3O Watt, Allow the iron to heat solder. Br a portable, and '60/40 rosin-core" posts for a few secondst twisted to maximum. Apply the irsn to the posts (near to the heated solder untit they become heated, then apply gecond puddle and will abruptly the solder or two, the iron. ) After a quickly rtiron should be time the run into all the. cracks, at which joint in a few seconds. and cools hardens moved. A soldered blhen splicing
is be=t to leave an exposed "test For trc:ubleshsoting purposes, it An poi nt " wherever a loop is connected into the protective circuit. to test a loop isolating when point helpful enormsusly is exposed tegt it {or continuity,
Without a test point it is necess'ary to open and are retroflr-
rewraF a splice, which is a troublesome job. The following mended rnethods of providing exposed test points.
?9 0'"
SCREU TERN I NFLS
r)J I TlP.OH TERIl I NRL CR
,1,
COHNECTOR
Figure 23-3
Figure 23-4
Figure ?3-3 depicts a ?-post, barrier tertinal blocki a small plastic block with two pairs o{ Ecrew terminals, which are separated by an insulating barrier. The two pairs of screw terminals are isolated from each othert but a netal strip provides continuity between both Ecreps o{ each pair. Figure 23-4 depicts a handy little item called a spade tonguer which ig =lipped onto a prepared wire post and tightly crimped in place (either nith a special crimping tool or a corner sf a sidecutter pliers' javrs.l rhe spade tongue *its perfectly under any type o{ strreh, terrninal, producing a much more e{ficient connection and affording great conveniencEl t*hen the connection must be removed and replaced during troubleshooting.
e-P0sT
TER}1I I.IHL
Figurr 23-5 Figure 23-S shows a one-sensor loop connected into a protective circuitn using a terminal block instead of a wrapped splice. Foth legs of the lcrcrp are fitted with spade tongues and fastened under the upper screws of a terminal blockr ;rS shonn. The ends of the severed protective circuit leg are likewise prepared and fastened under the lower screws rrn the terminal block. The continuity o.f this connection is the sa.ne as a spliced junction, but it provides conveniently exptrsed test points. To isolate the loop from the protective circuit (to test it for continuity), .just loosen the upper screws of the terrninal block.
P,PA
TEf
Figure 23-6 85
These terrninal blscks may also be introduced at intervals in long with wir-e runE to eliminate the need for penetrating wire insulation As pins when taking voltage readings along the protective circuit, (spade pair in two is cut circuit protective the 23-6, Fig, in sh13r*n
tr:ngues are attached ts each stripped end) and attached to a terminal for bleck. tNote that the block in Fig. ?3-= is situated vertically a making 23-6 ft:r FiS. in horizontally but cannection; a series rnaking parallel connection. ) lrlhen attaching a wire to a strrew terminal without using a spade bend the twisted post tongue, strip the wire end, twist it tightty; around the shaft of a screwdriver to form a hsok, then solder the hook. This ig the next best method to using a spade tongue and will prevent the gire strands frorn fraying and corroding under the screw terminal.
The uE,e of exposed test points should be restricted to areas where in the public areas of they witl not be accessible to tarnpering (i,e', a trBrnmercial premises, ) All it would take is a jurnper acrrrss the two One way to upper screws in Fig. 23-5 to shunt the loop out of circuit. provide a concealed test point is to use a covered telephone connecting block (,'basebsarO Ufock") instead of a barrier terminal block. Another handy technique makeg use of a 3.5mrn plug {"mini-plug") and jack set. A 3.5mm plug is the small plug usually found at the end of These nost tape recorder accessory rrtiresr rniniature headsets, etc. black plastic sleeve that gcrews off plugs usually have a cylindrical, to accomodate the wiring connecticlnsr as seen in Fig. 23-7.
SLEEVE
Figure 23.7 The "jatrk" is the female part of the setjack, which csmes with a screw-off sleever 35
Use Seen
the "in-Iine" in Fig. 23-4.
type
PROTEET I VE
SLEEVE
Figure ?3-B These plug & jack sets sffer a convenient way to improvise a "trap" or to monitor a ventilator E,Elnsgr, such as e "live trap" trip-wire, (see CLIF TRAPS- ) duct grille, etc; llB" The way to wire a plug./jack set is seen in the above figures: protective circuit severed of a endg the from is stribp"O of ingulation pair. The separate ends are passed through the gleeves of both plug 86
and jack and soldered to the terminalsr- then the sleeves are screwed in place to cover the connection. FLUE
JfiCT
Figure 2S-? l{hen the plug is inserted into the jack (as seen in Fig. Z3,-g, I csntinuity is egtablished. A slight tug at the wiring will the tr^lo parts, having precisely the sarne ef fect as reparatingseparate a clip trap.
In addition to a trap function, venient test point:
this plug./jack set provides a con-
FROTECTIUE EIREI]IT
Figurr 25-lO The tip of the plug is separated from the shaft by an insulative band- The tip is continuous with one of the terminals, the shaft is continuous with the other. FiS. Z3-1c shows how to apply the probes of a rneter to a plug for testing: One probe is applied to the tip (A), the clther is aPFtied to the shaft (8. ) This is identical to applying the probeg to strrew terminals. The tip and shaft are continuous r+ith the separate legs of wire. Ts use a meter on the jackr ein extra plug twithout a sleeve) be usedl Slip this plug int6-the jack and apply the meter.s probesmust to the plug's solder terminals as shown in Fig. ZS-11. .rRCl(
PFIOTE']TIUE CIRIUIT T
II I THOUT
SLEEUE }
Figure 23-11 87
The previous paragraphs refer to using a plug/jack set to achieve the same effect as seen in Fig. 73-6, which is direct continuity of the protective circuit pair. A plug/jack set may also be used ts connect a Ioop into the protective circuit, as shown in Fig. 23-5. -+E+=+r+=+E+E+=+8+3+-+3+3+Er+rr+E+r+tB+!E+-+E+E+=+=
A good source of standard tools and hardware items is,
U.E. EENERAL TOOL CO. IOO General Place Jeritrhof New York I l75S
This is a mail-order supplier. All prices are discounted {rom the A large tool catalog is available for 2.O0.
suggested retail.
-+s+rs+=+=+-+!.+E+E+E+a+-+E+E+!+-+r+=+E+r+E+3+-+
An excellent
source of supply for professional-grade burglar alarm
ccmponents and special equipment is,
EARRISON PROTECTIVE ELEtrTRBNICS
Kew
Box l2B Berdenr, Nrw York I t4l5
This supplier has been around the burglar alarm buginesg for many years and handles nothing but top-quality equiprnent. Their price:i are reasonable and they provide informational support to their customers. trle recommend this supplier to any reader who wishes to take the next step in the direction of learning this fascinating skill. Garrison will supply special 'package' sets of equipment, including supplEmtntary instructiong that conform with the in{ormation in this book. They stock the nl00rr control panel (and others), and will make retrcrmmendations pertaining to a customer's individual requirements. A catalog is 2.O0, which may be applied to any equiprnent order. 88
EOUIPI'IENT COST REFERENtrE =a- - -= == ==
t=
-!E=rr-=
The *olltrwing are typical retail prices of professional quality hurglar alarm components, (list conpiled in the Fallr 1gg4.) listing is provided as a reference to calculate the approximate costThis of installing a burglar alarrn system. t{holesale suppliers (r*ho depend on volurne salesi generally do not invite small orders from beginners, and are too busy to provide inf orrnational support. To avoiA malcing costly. tror-rbleEorne rnistakes, the beginner is advised to deal with a retail sr-rpplier who has installation experiencE!. CONTROLS}
Expect to pay about 75.OO for a'UL Listedr', basic control panel, such as the sne described in this material. I+ acc€lssory features are requiredr dln entry./exit-delay timer will cost about 6ct.oo, A bell cut-r:ff tirner, about 4o.oo. An AC srritching relay, about zo.oo. A permanent power supply (with ptug-in transf61rmer, trictcie charger and standby battery), about 80.Oo. Reliable control panels are available with built-in power supplyn entry/exit delay timers, and two zones, tor sbout 2(lo't)cl. (Ee sure that clear, supplementary wiring instructions arE included with any multi-f eatr_rred panel. ) BELLS & SIRENS> A uL Listed belln contained in a weatherproof cabinet with pre-wired tamper switches will cost about z5.o{r. A siren with speaker, rernote driver and tamper protected cabinet cost about loo'(io. Remenber that a 12 volt system is recommended will i+ an exceptionally loud siren is required. f,IABNETIC BhIITtrH EET}
UL Li sted,
operations) will cost about g.OO to PLUNEER SWITCH>
(rated at ,nore than one mi I I ion 6.OCr per set, nith cover.
hleatherproof type: 4. OO.
LEAF ShIITtrH> 5.
trLIP
TRAP}
UL
OO.
Listed type:
4.OO.
I.IERCURY SWITCH)
UL Listed typer wi th adjustable bracket: llith adjustable bracket & door cord, 12. OO. VIBRATION DETECTOR}
UL SWITCH IIAT>
Listed type:
B. OO.
lO +t. length x 3O,, width: 89.
SO,OO
per roll.
lO.OO.
SHUNT LBCK>
Round key
PHOTOELECTRIC SENSOR>
PROXIT.IITY SENSOR>
type: 15.OO. UL
About
Listed type: Average 15O.OO.
35O.OO.
ULTRA-5ONItr I'IOTION DETEtrTOR>
About l50.OO.
PASSIVE INFRA-RED T.IOTION DETEtrTOR> T.IICRO-TdAVE I.IOTION DETECTOR>
WIRE>
FtEDEtrB: SO.OO.
About
About
15O.OO.
175.OO,
27/2= B,OO per lOO ft. coil. S5.OO per SOO {t. spoot. Lacing wire: (hard-drawn copper) ?O.OO per 5OO ft. spool
FOIL> B.OO
per
5OO
+t. roll.
ELASS-BREAK DETECTTIR>
FIULTI-''IETER}
UL
Sel{-adhesive type: lZ.OO.
Listed typer
Standard type:
7.OO.
About 55.OO.
Peters I'leter (specialized for alarm work) ARRIII'I
T-lB
STAPLE-6UN>
FEELER BITS>
40.OO. Staples, 2.OO per
7E.OO.
ITOOO.
Range from 10.OO to ?O.OO, depending on length
and
di ameter.
In the way of miscellaneous hardware and fasteners, a box of lOO *6 screh,s costs about ?.5O. Spade tongues: about 1O.OO per lOO, Because retail
equipment suppliers make a better profit on the seII to beginners, they generally will include such item as fasteners with an order.
trclmponents they
incidental
90
The burglar alarm kit you've installed urill protect your property, family, and valuables, right? Not necessarily. A majority of the so-called burglar alarms currently in use can be defeated by amateur crooks using the least sophisticated methods. And many systems will malfunction within a matter of months, leaving the do-it-yourselfer with a collection of useless hardware fastened to the
walls.
T
Tricks of the Burglar Alarm Trade will help you find and fix the weaknesses in your current system or show you how to select and
install a new one that will make your home or business truly secure. And you won't have to wade through technical jargon, cryptic diagrams, or complicated references to electrical theory. Author Mike Kessler's straight-
forward, get-down-to-the-basics approach will familiarize you with the principles that govern all closed-circuit burglar alarms and then provide you with countermeasures that will defeat any attempt to bypass your
system.
_T_
Whether you own an apartment, liquor store,
or mansion, Tricks of the Burglar Alarm
Trade will help you keep your property and loved ones safe from intruders. A PALADIN PRESS BOOK ISBN 0-87364-550-2
