BWD MINI-LAB 603B Manual page 31

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603B
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APPLICATIONS (conMnued)
5
.
5
USE
OF
AMPLIFIERS IN
A
SIMPLE PUBLIC
ADDRESS SYSTEM
(Cont'
d)
Connect
the
equipment
as
shown below:-
The Voltage Amplifier gain
control
can be
used
as
a 'Volume
Control'.
5.6
WIEN
BRIDGE
OSCILLATOR
USING
THE
OPERATIONAL
AMPLIFIER;
Positive
feedback applied
to
an
operational amplifier
will
generally cause
the amplifier to oscillate.
If
the
feedback network
is
arranged
in
such
a
way
as to apply
positive
feedback
at
one
frequency
only, the amplifier
will oscillate at that
frequency.
The frequency
where
the
phase
shift
is
0°
is
given by:-
f
=_1
2nRC
5-7