TM 5-6350-262-14/6
NAVELEX 0967-LP-466-9062
TO 31 S9-4-33-1
(2) Alarm generated by impedance of ≤ 10K
and is switched on or off by the analog switch.
4-11.
Driver or Buffer Amplifier
between the inner and outer enclosure. This condition
The driver or buffer amplifier is also a switched on or off
occurs whenever an intruder attempts to bypass the
by the output of the analog switch. The driver amplifier
tamper switches by cutting through the sides of the
accepts the output of the VCO, amplifies it and applies
enclosure. This represents an impedance change and is
the signal to the power amplifier.
accepted as an alarm condition by the impedance
4-12.
Power Amplifier
monitor. A tamper alarm indication is sent to the Control
This circuit increases the audio signal from the driver
Unit which activates the level detector of the Audible
amplifier to the power level needed to operate the
Alarm, turning the unit on and producing an audible
speaker. The power amplifier produces 25 watts. Since
alarm.
its output reflects its input, the amplifier is always
connected to the regulated +27.5 to 28 volt line.
(3) Alarm initiated by door tamper switch
4-13.
Speaker
Whenever an intruder attempts to get into the audible
This is the acoustical alarm component of the Audible
alarm through the outer enclosure door, the tamper
alarm. It is driven by the power amplifier and produces
switch opens. In the open position the + 5 V dc is
an audible signal (145dB) during an alarm condition.
interrupted, which provides an alarm output of < 1V dc
4-14.
Alarm Conditions
to the control unit.
a. There are four separate conditions that will cause an
alarm output of 1V dc or less to be provided to the
(4) Alarm initiated by pry-off tamper switch
control unit:
Whenever an intruder attempts to disable the audible
alarm by prying it loose from its mounting surface, the
(1)
Alarm sensed by the control unit.
external or pry-off tamper switch opens. This switch is
Whenever an alarm is sensed by the control unit the
also in series with the + 5V dc no-alarm output voltage.
voltage at L2-1, with respect to L2-2, drops to 1-volt or
Therefore the + 5V dc output to the control unit is
less and an alarm condition (level change) is sent to the
interrupted, which provides an alarm output of < 1V dc
level detector of the Audible Alarm. The level detector
to the control unit.
will turn on the analog switch which will activate the
ramp generator, VCO and driver providing a signal to
4-15.
Operation Under Emergency Power
the power amplifier and speaker and subsequently, the
The Audible Alarm automatically switches to emergency
audible alarm sounds. In addition, the analog switch will
power supply when primary a.c. power fails. It should
turn on the impedance monitor, sending a tamper alarm
not be allowed to operate on battery power above for
indication back to the Control Unit.
more than 24 hours (12 hours if battery is two years old
or if operating temperature is -20F.) If ac power is off
for more than the specified maximum, the battery must
be recharged as directed in chapter 5. Failure to do so
may create a safety hazard.
Change 2 4-2
