EasyManua.ls Logo

Sharp SM-510H - Equalizer Amplifier

Sharp SM-510H
16 pages
Save Page as PDF
Print Icon
To Next Page IconTo Next Page
To Next Page IconTo Next Page
To Previous Page IconTo Previous Page
To Previous Page IconTo Previous Page
Loading...
Referring
to
the
equivalent
circuit
in
Fig.
3
and
the
principle
circuit
in
Fig.
4,
we
explain
the
operation
of
the
circuit.
The
input
signal
is
applied
in
between
K313
and
earth
and
then
to
the
PIN
8
via
the
C301.
The
Q1
and
Q2?2
serve
as
differential
amplifier,
which
works
to
connect
the
signal
given
with
the
single
power
supply
(from
the
previous
stage)
with
the
amplifier
operated
on
the
split
power
supply.
The
Q3,
D1
and
D2
form
constant
voltage
circuit.
The
signal,
which
is
differencial-amplified
in
the
Q1,
is
supplied
to
the
base
of
Q4
via
the
PIN7
.
The
D6
~
D8,
connected
to
the
collector
of
Q4,
give
an
appropriate
bias
to
the
next
stage
and
also
supply
thereto
the
balanced
signal
with
the
earth
positioned
at
the
center.
The
Q11
is
NPN
transistor.
These
PNP
and
NPN
transistors
form
complementary
circuit.
Therefore,
the
upper
half
of
waveform
is
amplified
at
the
Q401
via
the
PIN
2
and
the
lower
half
amplified
at
the
Q403
via
the
PIN
13
,
which
then
appear
in
the
K313
as
output
waveform.
Since
the
DC
voltage
of
K313
is
of
OV,
it
is
not
needed
to
use
the
coupling
capacitor
conventionally
employed
in
the
SEPP
type
amplifier.
(The
name
of
OCL
is
derived
from
this
fact.)
The
Q15
works
to
filter
the
ripple
of
+B
if
the
capacitor
is
inserted
to
the
PIN
4
.
The
Q11
and
Q13
form
current
limitter.
If
an
abnormal
current
runs
in
the
Q401
and
Q403,
DC
voltage
increases
in
the
R313
and
R315
and
reaches
the
base
of
Q10
and
Q13
via
the
PIN
1
and
12
,
causing
the
signal
to
be
grounded.
The
minimum
current
required
for
operating
this
protection
circuit
can
be
adjusted
by
the
values
of
the
R309
and
R311.
The
R305
is
a
resistor
to
determine
the
negative
feedback
amount.
With
the
R305
lessened,
the
nagative
feedback
amount
decreases,
thus
increasing
the
gain
of
the
maplifier.
To
the
PIN
6
and
7
is
connected
the
capacitor
for
preventing
the
oscillation.
The
OCL
amplifier
is
an
ideal
amplifier.
from
the
following
points;
Its
low
frequency
response
characteristic
is
superior
in
particular
because
of
the
absence
of
the
coupling
capacitor,
and
flat
reproduction
is
assured
up
to
as
low
as
10Hz
in
the
case
of
main
amplifier
alone.
In
addition,
negative
feedback
is
sufficiently
applied
due
to
the
IC
driver
to
remarkably
lessen
the
distortion.
2.
EQUALIZER
AMPLIFIER
OUTPUT
!
Fig.
5
Equivalent
Circuit
Fig.
6
Equalizer
Amplifier
Explained
here
is
the
operation
of
this
circuit.
The
internal
equivalent
circuit
of
the
IC201
is
of
directcoupled
3-stage
amplifier.
The
first
stage
Q1
serves
as
grounded
emitter
circuit
and
the
input
signal,
coming
via
the
K202,
is
amplified
at
the
base
of
QI
and
then
appears
in
the
collector.
In
order
to
increase
the
collector
load
of
Qi
the
second
stage
Q2
and
third
stage
Q3
are
made
an
equivalent
circuit
with
Darlington
connection,
thus
the
input
impedance
at
the
second
stage
is
increased.
The
last
stage
Q3
serves
as
grounded
emitter
circuit
and
obtains
the
output
from
the
collector.
The
bias
is
supplied
from
the
emitter
(PIN
5)
of
Q3
to
the
base
(PIN
2)
of
QI
via
the
R205.
(DC
negative
feedback
type.)
agin,

Related product manuals