CIRCUIT DESCRIPTION
Model
2001
The following circuit descriptions are referenced to the
schematics appearing in Section
6.
4.3
POWER SUPPLY (PS6)
The PS6 power supply provides three regulated voltages and
an optional "pen-lift'' circuit.
AC POWER
&
RECTIFIER CIRCUITS
A dual-primary transformer allows operation at a line vol-
tage of 115 or 230 volts. AC power is supplied through a
4
wire receptacle from the Front Panel ON/OFF switch.
The transformer is located away from the sweep drive
module to reduce magnetically coupled line ripple. Un-
regulated plus and minus voltages are supplied by two full
wave rectifier circuits and filtered by
C1 and C7. A 12 pin
plug, mounted to the printed circuit board, provides access
to three unregulated voltages as well as the regulated +18
-18, and
-20V. This plug also accepts a scope horizontal
signal for connection to a Rear Panel connector. The pen-
lift switching circuit is also enabled through this plug.
PEN
LIFT OPTION
lns~allation of K50 and Rear Panel jacks provides a contact
closure which occurs during the sweep on-time. 011 is
normally conducting from current supplied through pin
9
of the 12 pin plug. When the base drive to 011 is removed,
the relay
is
energized by the turn-on of 012. To prevent
early failure of the relay contacts, the relay is only ener-
gized during slow sweep speeds and in the manual position
of the front panel sweep rate selector.
+I8
VOLT
SERIES REGULATOR
Regulation is provided by
IC1 which contains its own inter-
nal reference supply.
R9 provides an adjustment to +18.00
volts. An external pass transistor, 02, boosts the current
capability, and
01 improves the current limiting character-
istics of
IC1 by providing amplification before limiting.
The +18 volt supply is protected against reverse voltage by
CR7.
-18 VOLT SERIES -SHUNT REGULATOR
The voltage reference for this supply is obtained from the
+I8 volt supply through R20, and R19 provides the feed-
back which is applied to IC2 which provides high gain forc-
ing 05 to maintain a shunt regulated voltage across
R13.
03
and 04 provide the series pass element and are con-
nected as a compound emitter follower so that the voltage
across R13 is not loaded heavily. Short circuit protection
of
05
is provided by
CR8.
Current limiting
is
provided by
05, when
06 conducts sufficiently to forward bias CR9
and CR 10. Reverse voltage protection is provided by CR12.
-20 VOLT SERIES REGULATOR
The reference voltage for the
-20V supply is applied to a
differential amplifier, 09 and 010, which in conjunction
with 08 provides a compound emitter following action
similar to the pass element of the -18V supply.
CR 17 provides reverse voltage protection. Current limiting
is provided by shutting down of the -18 volt supply by 07
through CR14 to the base of 05, reducing the reference vol-
tage to the base of
09. This action is helped along by the
conduction of CR13 if the -20 volt supply drops below -18
volts.
4.4
SWEEP
RATE
(MODULE M1H)
MIH SWEEP RATE GENERATOR
This module generates a variable rate square and triangular
waveform. Front Panel switching provides recurring, trig-
gered, or manual modes. The triangular waveform is a 32
volt peak-to-peak signal with a sweep time variable from
10ms to 100 seconds in four steps. Retrace time is held
constant at the fastest sweep time of each range. The tri-
angular waveform
is
used to provide the sweep drive and
the scope horizontal signals.
The square wave output is a -1 to +15 volt signal whose
-1
volt level corresponds to the sweep time and whose 15 volt
level corresponds to the retrace time. The square wave is
used to provide blanking of the RF output during retrace
time.
Triangular waveformsaregenerated in an integrator, 01, 02,
03, and 04, by applying positive and negative voltage levels
to the integrator input. When the integrator positive ramp
output exceeds a threshold voltage, a bi-stable hysteresis
switch
is
switched, reversing the polarity of the integrator dc
input, causing the triangular waveform to start down toward
another threshold. If the module
is
programmed in a recur-
ring mode, the negative ramp will trip the hysteresis switch
producing continuous oscillations. The hysteresis switch
output is clipped on the negative polarity and is used for
blanking (pin 10).
The symmetrical square wave output from the hysteresis
switch (pin
9)
isconnected, through the Front Panel SWEEP
TlME vernier and one of the range determining resistors of
the SWEEP TlME selector switch, to the integrator input
(pin 7). Since the integrator output voltage change is pro-
portional to the input voltage level, the SWEEP TlME ver-
nier provides a sweep time increase by reducing the hysteresis
switch output if the polarity is negative. If the polarity
is
CIRCUIT
DESCRIPTION
The following circuit descriptions are referenced to the
schematics appearing in Section
6.
4.3 POWER SUPPLY
(PSG)
The
PS6
power
su
pply provides
three
regu lated voltages and
an
optional
"pen-lift"
circuit.
AC
POWER &
RECTIFIER
CIRCUITS
A
dual·primary
transformer
allows
operation
at
a line vol-
tage
of
115
or
230
volts. AC
power
is
su
ppl ied
through
a 4
wire receptacle from
the
Front
Panel
ON/OFF
switch.
The
transformer
is
located away
from
the
sweep
drive
module
to
reduce magnetically
coupled
line ripple. Un-
regulated
plus
and
minus
voltages are supplied by
two
full
wave rectifier
circuits
and filtered by
Cl
and C7. A
12
pin
plug,
mounted
to
the
printed
circuit
board,
provides access
to
three
unregulated voltages as well as
the
regulated
+18
-18, and -20V.
This
plug also
accepts
a
scope
horizontal
signal
for
connection
to
a Rear Panel
connector.
The
pen-
lift switching
circuit
is
also enabled
through
this plug.
PEN
LI
FT OPTION
I nstallation
of
K50
and Rear Panel jacks provides a
contact
closure
which
occurs
during
the
sweep on-time.
011
is
normally
conducting
from
current
supplied
through
pin 9
of
the
12 pin plug. When
the
base drive
to
011
is
removed,
the
relay
is
energized
by
the
turn-on
of
012.
To
prevent
early failure
of
the
relay
contacts,
the
relay
is
only
ener-
gized
during
slow sweep
speeds
and in
the
manual
position
of
the
front
panel sweep rate selector.
+18
VOLT
SERIES
REGULATOR
Regulation
is
provided
by
ICl
which
contains
its own inter-
nal reference supply.
R9
provides an
adjustment
to
+18.00
volts. An external pass transistor,
02,
boosts
the
current
capability, and
01
improves
the
current
limiting character-
istics
of
ICl
by providing amplification
before
limiting.
The
+18
volt
supply
is
protected
against reverse voltage by
CR7.
-18 VOLT
SERIES
-
SHUNT
REGULATOR
The
voltage
reference
for this
supply
is
obtained
from
the
+
18
volt
supply
through
R20,
and R 19 provides
the
feed·
back which
is
applied
to
IC2 which provides high gain forc-
ing
05
to
maintain
a
shunt
regulated voltage across R13.
03
and
04
provide
the
series pass
element
and are con-
nected as a
compound
emitter
follower so
that
the
voltage
across R 13
is
not
loaded heavily.
Short
circuit
protection
of
05
is
provided by
CR8.
Current
limiting
is
provided by
05,
when
06
conducts
sufficiently
to
forward bias
CR9
and CR 10. Reverse voltage
protection
is
provided by CR 12.
4-4
Model 2001
-20 VOLT
SERIES
REGULATOR
The
reference voltage for
the
-20V
supply
is
applied
to
a
differential amplifier,
09
and
010,
which
in
conjunction
with
08
provides a
compound
emitter
following action
similar
to
the
pass
element
of
the
-18V
supply.
CR 17 provides reverse voltage
protection.
Current
limiting
is
provided by
shutting
down
of
the
-18 volt
supply
by
07
through
CR
14
to
the
base
of
05,
reducing
the
reference
vol-
tage
to
the base
of
09.
This
action
is
helped along by
the
conduction
of CR
13
if
the
-20
volt
supply
drops
below -18
volts.
4.4
SWEEP
RATE (MODULE M1H)
M1H SWEEP RATE
GENERATOR
This
module
generates a variable
rate
square
and triangular
waveform.
Front
Panel switching provides recurring, trig-
gered,
or
manual modes.
The
triangular waveform
is
a 32
volt
peak-to-peak signal
with
a sweep
time
variable
from
10ms
to
100
seconds
in
four
steps.
Retrace
time
is
held
constant
at
the
fastest sweep
time
of
each range.
The
tri-
angular waveform
is
used
to
provide
the
sweep
drive and
the
scope
horizontal
signals.
The
square wave
output
is
a
-1
to
+15
volt signal
whose-l
volt level
corresponds
to
the
sweep
time
and
whose
15
volt
level
corresponds
to
the
retrace
time.
The
square
wave
is
used
to
provide
blanking
of
the
RF
output
during
retrace
time.
Triangular waveforms
are
generated
in
an
integrator,
01,02,
03,
and
04,
by
applying
positive and negative voltage levels
to
the
integrator
input. When
the
integrator
positive ramp
output
exceeds
a
threshold
voltage, a bi-stable hysteresis
switch
is
switched, reversing
the
polarity
of
the
integrator
dc
input,
causing
the
triangular waveform
to
start
down
toward
another
threshold.
If the
modu
Ie
is
programmed
in a recur-
ring
mode,
the
negative
ramp
will trip
the
hysteresis switch
producing
continuous
oscillations.
The
hysteresis switch
output
is
cl
ipped
on
the
negative
polarity
and
is
used for
blanking (pin 10).
The
symmetrical
square
wave
output
from
the
hysteresis
switch (pin 9)
is
connected,
through
the
Front
Panel SWEEP
TI
ME
vernier
and
one
of
the
range
determining
resistors
of
the
SWEEP
TI
ME
selector
SWitch,
to
the
integrator
input
(pin 7). Since
the
integrator
output
voltage change
is
pro-
portional
to
the
input
voltage level,
the
SWEEP TIME ver-
nier provides a sweep
time
increase by reducing
the
hysteresis
switch
output
if
the
polarity
is
negative. If
the
polarity
is
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