Elenco Electronics MO-1251 Manual do Utilizador descarregar pdf (Página 32)

100

ping hit anywhere

in the

neigh-

borhood

usually

wiped out the

control

center. Fortunately,

false- triggering

no longer a problem

in the

newer pan-

els,

provided that

they are

securely

grounded to

the main

water pipe. But

if you have

one of the early centers

that

keep sending

false alarms,

you

now know

why. Also, grounding

not, some computerized

control

cen-

ters

still get clobbered

by a nearby

lightning

strike.

High -tech control

The difference

between basic -sol-

id -state and

high -tech control

centers

is that the

high -tech

device contains

microprocessor

that usually

controls

everything

except the

loop sensors.

For

example, even

the

simplest

high

-tech panel

provides

for a 24-

hour panic

switch and

two protective

loops: an

instantaneous

loop for ev-

erything except

the entry

doors, and

delayed

-entry

loop. Instead

of having

to arm and disarm

the door

sensor by

using

a bypass

keyswitch

for the front

door,

the microprocessor

allows

the

LOOP

CONTROL

FIG.

4-AN END -OF- LINE

-RESISTOR

loop

protects against anyone

bypassing

the

loop by simply

short -circuiting

the

wires.

user

a safe period

of 0-45

seconds to

get out

of the

house after

the alarm

armed. Similarly,

the user

can take

0-45 seconds

turn off the

alarm

after entering

through

a door.

The

microprocessor

also

provides

delayed entry

warning so

that you

don't

forget

to turn

off the alarm.

The

warning is usually

low-

volume

buzzer

that

will sound

off as

soon as

the door

is opened

-so you

don't

for-

get to

disable the

alarm -or,

sounds

off after 30

seconds as

warning that

in another

seconds the

main

alarm

siren or bell

will sound

off

if not dis-

abled.

The panic

function

is for emergen-

cies that

usually

require

a neighbor's

attention

rather than

the police

or fire

departments.

When

alarm system

is connected

to a central

station, all

alarm

conditions

except

the panic

loop are

transmitted

the central

sta-

tion.

Usually -not

always

-a panic

switch

sounds

the alarm

bell

or siren

to attract

a neighbor:

It might

be used

by an invalid.

both the

simple and

the

most complex

high -tech

alarms,

the panic

loop

will also arm

the rest

the alarm.

Why

panic

-arm the

alarm? Well,

assume

that

you're

home alone

and

you hear a

noise in the yard.

You don't

know

whether the sound

from an

intruder

if you're just

hearing

things

that go

bump

in the night.

your

alarm

sends a signal

to a central

station,

you don't

want to

hit the

emergency

hold -up

switch because

to do

that

will send an

alarm to

the

central

station,

which

might result

false -alarm

to the police.

you

hit

ARM

MONITOR

CLEAR

BYPASS

SCAN

RESET

EMERGENCY

ENTER

MEMORY

PROGRAM

EMERGI

FIG. 5 -THE

MOST

ADVANCED COMPUTERIZED

home -alarm

systems provide

both user

programming and

an alpha display

of all operating

conditions

and

circuit

problems.

.0 (

FIG. 6-A

SMALL SILICON

SENSOR

and

Its control

unit

can distinguish

between

the

footsteps of animals

humans.

the panic

switch,

which causes the

microprocessor

to turn

on the yard

lights, sound

the alarm

siren

that

your

neighbor

will peek out

his

win-

dow to

see what's up,

and automat-

ically arm

your alarm

system

if it had

been off.

If the sound

was actually

made by

intruder, and if

he attempts to enter

your home,

he triggers

the alarm to

the

central station.

The

panic

loop

is similar to

the 24-

hour,

or perimeter,

protective

loops of

some (usually

more expensive)

alarm

systems.

The primary

difference

that a

24 -hour loop

provides

full -time

24 -hour protection

even

if you're

home

with

most of

the alarm

system

turned

off. If the 24

-hour loop

is trig-

gered,

the control

center

sends an

alarm

to the central

station and

arms

the rest

of the alarm

system. (You

would

normally

keep the

non -24

-hour

loops

off so that you could

move about

freely,

without having to

worry about

whether opening

a closet

or a door

would

trigger

the alarm.)

Figure 3

is a generic block

diagram

of a low

-cost microprocessor-con

trolled control

center.

Note that

does

not

contain

a central

-station

di-

aler, although there

is a

set of "dry

contacts" that

can be

used to activate

accessory dialer.

(Dry

contacts

means

switch contacts

that have

resident

voltage source.)

Also note

that

there

is no EOL power

supply

for

the

loops -the

loops are powered

from

the center's

power

supply.

The more advanced

high -tech con-

trol

centers that

are used

in the

home,

such as those

in Napco's

800

and

900

series,

contain

from six

to nine pro-

tective

circuits

that can

set

intruder

loops, a panic

alarm,

fire pro-

1 2 ... 27 28 29 30 31 32 33 34 35 36 37 ... 99 100

Comentários a estes Manuais

Sem comentários

Elenco Electronics MO-1251 Manual do Utilizador Página 32

Comentários a estes Manuais