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Farnell TSV 70 - Circuit Description; Overall Supply Architecture; 35 V 10 A Range Circuitry; Control Circuitry Function

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SECTION
11|
CIRCUIT
DESCRIPTION
The
supply
consists
of
a
mains
transformer
feeding
two
bridge
rectifier,
reservoir
capacitor
and
series
regulator
Systems.
On
the
35
volts
l0
amps
range
the
outputs
of
the
two
systems
are
paralled
by
switch
Sl.
The
series
regulator
bank
driver
inputs
are
paralled
by
SlA
and
driven
from
the
main
control
circuit
board
No,
1.
On
the
70
volts
5 amps
range
the
outputs
of
the
two
systems
are
connected
in
series.
The
upper
system
is
driven
from
the
main
control
circuit
board
No.
1,
and
the
lower
system
is
driven
from
circuit
board
No.
2.
35
Volts
1O
Amps
RANGE.
Mains
Transformer
MT1l
feeds
MR1
from
a
37V
R.M.S.
secondary
winding.
MR2
is
fed
from
a
second
37V
R.M.S.
secondary.
The
negatives of
reservoir
capacitors
C21
and
22
are
connected
to
the
negative
output
terminal
via
fuse
F2,
switch
DlD,
current
monitoring
resistor
R67, and
switch
S3.
The
positive
is
connected
via
series
regulators
VTl7-23
to
the
positive
output
terminal.
The
negatives
of
reservoir
capacitors
C25
and
26
are
connected
via
fuse
F3,
current
monitoring
resistor
R67
and
switch
S3
to
the
negative
output
terminal,
The
positive
is
connected
via
series
regulator
transistors
VI24 -
3O
and
switch
SIC
to
the
positive
output
terminal.
The
input
bases
of
VTl7
and
VT24
are
paralled
by
SIA,
The
control
circuit
of
circuit
board
No.
1
consists
of
Diodes
Dl
and
D2,
and
Rl
which
are
fed
from
a
36-0-36V
winding
on
MTl
and
feed
reservoir
capacitors
Cl
and
c2
This
provides
an
unstabilised
D.C.
supply
for
zener
diodes
Z1
and
z2
which
are
fed
via
R2.
Zl
and
z2
provide
a
+15
- 0 -
-10
Volt
supply
for
the
reference
and
control
amplifier
circuitry.
VT4,
Rll,
Z4,
Rl4
and
R15
comprise
a
constant
current
source
which
feeds
z3,
R8
and
T2,
pins
3
and
18
being
linked
externally.
Z3
is
the
main
reference
zener
diode
and
provides
a
+5.1V
source
with
respect
to
Pin
l1
which
is
connected
to
the
+ SENSE
front
panel
terminal.
Pl
and
P2
are
the
coarse
and
fine
voltage
controls
on
the
front
panel
and
are
connected between
the
"-SENSE"
terminal
and
Pin
17
on
control
circuit
board
No.l.
Pin
7
is
connected
via
Rl6
to
VI5
base.
A
potential
divider
comprising
Pl,
P2,
T2
and
R8
forms
the
output
voltage
sensing.
The
control
amplifier
vT5,
6,
8,
9,
10
drives
emitter
follower
vT7.
drives
the
series
regulator
banks
VT17-23
and
vT24-30.
connection being
from
Pin
13
on
the
circuit
board
No.
1
via
the thermal
trip
TT1
to
Pin 9
on
circuit
board 2 then
via
Rlll
on
circuit
board
No. 2
to
Pin
10 and from
there
to
the
base
of
VTl7
and
via
SlA
to
the
báse
of
VT24.
The
control
loop
acts
in
such a sense
as
to
oppose
any
signal
change
on
vT5
base,
- 4 -
This
The

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