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Tektronix FG 5010 User Manual

Tektronix FG 5010
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If
excessive
collector
current
is
drawn
through
Q1511
,
this
is
sensed
via
R1520
,
and
the
non
-
inverting
input
of
U1432A
moves
negative
.
The
output
in
turn
moves
nega
tive
,
reducing
conduction
through
Q1510
and
thus
,
Q1511
.
Stabilization
of
U1432A
is
provided
by
Q1420
and
CR1523
,
which
come
into
operation
whenever
the
output
,
pin
1
,
of
the
amplifier
rises
more
than
two
junction
drops
above
the
+8
V
at
the
cathode
of
CR1523
.
At
that
point
,
Q1420
con
ducts
to
limit
the
range
of
U1432A
by
furnishing
another
current
path
for
the
inverting
input
of
U1423A
.
Main
Current
Limiter
.
Amplifier
U1432B
,
transistor
Q1422
,
and
related
components
make
up
the
Main
Current
Limiter
.
Operation
of
this
circuit
and
that
of
the
Current
Limit
Amplifier
is
similar
.
Sensing
of
the
current
is
performed
across
the
parallel
combination
of
R1510
,
R1511
,
and
R1512
.
When
the
main
current
limit
is
reached
(
about
4
am
peres
)
,
U1432B
pulls
negative
on
the
base
of
Q1510
,
reduc
ing
the
drive
to
the
power
module
pass
transistor
.
Amplifier
U1432B
is
held
from
moving
out
of
its
operating
range
by
the
action
of
Q1422
and
CR1522
.
Over
-
voltage
Protector
.
This
circuit
consists
of
compa
rator
U1320
,
SCR
Q1310
,
and
related
components
.
Should
the
+5
V
line
rise
too
positive
,
U1320
provides
the
firing
potential
for
Q1310
,
which
fires
and
pulls
the
+5
V
line
to
ground
potential
.
Current
surges
during
SCR
turn
-
on
are
limited
by
R1410
.
If
Q1310
is
fired
,
the
fuse
through
which
the
current
is
supplied
from
the
+8
V
power
module
supply
will
open
.
Driver
Stage
.
This
circuit
consists
of
common
-
emitter
stage
Q1510
and
Q1511
.
The
base
of
Q1510
is
the
junction
of
the
output
of
amplifiers
U1420
,
U1432A
,
and
U1432B
.
Thus
,
depending
on
the
operating
conditions
of
the
regula
tor
(
normal
,
overcurrent
,
etc.
)
,
one
or
another
of
the
amplifi
ers
will
have
control
of
Q1510
.
(
The
other
two
amplifiers
will
be
kept
in
bounds
by
the
self
-
regulating
circuit
in
each
stage
.
)
Emitter
-
follower
Q1510
furnishes
the
base
drive
current
for
driver
Q1511
,
which
is
also
an
emitter
-
follower
,
and
pro
vides
the
base
drive
for
the
Power
Module
pass
transistor
,
which
is
located
off
the
FG
5010
chassis
for
better
cooling
characteristics
.
23
12
V
SUPPLIES
Introduction
These
two
voltage
regulator
circuits
,
which
are
located
on
the
Sine
Shaper
Board
,
derive
power
from
the
Power
Module
voltage
supplies
.
The
output
voltages
are
applied
throughout
the
FG
5010
circuits
.
Theory
of
Operation
-
FG
5010
+
12
V
Regulator
The
regulator
consists
of
amplifier
U1520
,
transistors
Q1530
and
Q1630
(
and
the
pass
transistor
in
the
power
module
)
,
plus
related
components
.
The
+26
V
from
the
Power
Module
enters
the
board
at
P1700
pin
12A
and
12B
,
through
fuse
F1610
to
a
filter
cir
cuit
.
This
consists
of
L1620
,
C1620
,
and
C1523
.
From
L1620
,
the
+26
V
is
connected
to
both
supplies
to
act
as
a
current
source
.
The
+26
V
leaves
the
board
through
filter
L1221
and
C1220
for
application
to
the
Loop
1
circuits
.
Reference
for
both
supplies
is
6.2
V
Zener
diode
VR1431
.
This
voltage
is
applied
through
R1430
to
the
non
-
inverting
input
of
U1520
.
The
inverting
input
of
the
amplifier
is
con
trolled
by
the
voltage
at
the
wiper
arm
of
R1427
,
the
+12
V
adjustment
.
The
+12
V
is
applied
to
the
top
of
divider
R1426
,
R1427
,
and
R1425
,
so
the
voltage
at
pin
2
of
U1520
ranges
from
+5.9
V
to
+6.5
V
,
approximately
.
The
voltage
resulting
at
the
output
of
U1520
controls
driver
transistor
Q1630
,
which
in
turn
controls
the
pass
transistor
in
the
Power
Module
.
At
the
output
of
U1520
,
Zener
Diode
VR1430
prevents
the
base
of
Q1630
from
going
beyond
+18
V
,
limiting
the
output
voltage
in
case
of
amplifier
failure
.
Current
limit
tran
sistor
Q1530
senses
the
voltage
across
R1535
,
and
,
should
the
current
rise
to
900
mA
,
Q1530
conducts
to
reduce
the
output
current
to
400
mA
under
a
direct
short
across
the
output
.
(
This
is
called
fold
back
current
limiting
)
.
The
+12
V
output
is
fed
off
the
circuit
board
as
two
sources
,
the
+12
V₁
and
+12
V₂
.
Each
of
these
output
lines
is
filtered
by
an
LC
circuit
before
leaving
the
board
.
Resistor
R1540
provides
protection
for
Q1630
in
case
the
FG
5010
is
installed
in
an
energized
Power
Module
.
If
during
connection
the
pass
transistor
collector
did
not
connect
,
Q1630
would
attempt
to
draw
the
entire
load
,
and
destroy
itself
.
However
R1540
limits
the
output
current
if
this
should
occur
.
-
12
V
Regulator
The
12
V
Regulator
consists
of
amplifier
U1521
;
tran
sistors
Q1611
,
Q1610
,
Q1430
,
and
the
pass
transistor
on
the
Power
Module
;
and
related
components
.
The
regulator
receives
the
-
26
V
from
the
Power
Module
and
converts
it
to
the
12
V
for
use
in
the
FG
5010.
The
–
12
V
regulator
is
very
similar
in
operation
to
the
+12
V
regulator
,
except
for
the
polarity
of
the
output
.
-
The
26
V
is
applied
through
fuse
F1630
and
input
filter
L1640
-
C1530
-
C1525
to
the
regulator
circuit
,
and
through
4-45

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Tektronix FG 5010 Specifications

General IconGeneral
BrandTektronix
ModelFG 5010
CategoryPortable Generator
LanguageEnglish

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