46018-0198 <90-00007>
P
AGE
3
CIRCUIT DESCRIPTION
F
ig. 1 shows the 46018 Audible Alarm functional schematic.
The circuit consists of:
An Oscillator
The oscillator receives a ground from any one of four inputs;
each of the inputs having four common pins. When grounded, a
voltage comparator enables the oscillator tones.
DIP Switches
The oscillator feeds two separate DIP switches from inputs 1
and 2 or inputs 3 and 4. each switch contains eight manually set
selectors. Activation of input 1 overrides activation of inputs 2, 3
or 4 for alarm priority purposes. Input 1 automatically switches
to the most important alarm levels.
A Function Generator
The frequency tones route to a function generator strapped for a
sawtooth or squarewave (low or high tone) alarm signal configu-
ration.
An Operational Amplifier
The signal routes through an operational amplifier where the
front panel “LEVEL ADJ” potentiometer (R26) adjusts the
signal gain.
Two Panel Speakers
The panel speakers audibly present the generated alarm signal.
A Voltage Regulator
The voltage regulator consists of transistors Q1 and Q2 that
provide a regulated voltage of -20 VDC for the module.