Datapulse 101 Manual

SECTION 1
SPECIFICATIONS
l. 1 GENERAL INFORMATION
The Datapulse Model 101 is an unusually compact high performance
and low cost pulse generator. Unique circuit design utilizing a minimum
of advanced solid state components, sets new standards for pulse generator
reliability and economy and extends versatility.
The instrument is designed for a wide spectrum of pulse testing,
circuit development and general laboratory applications. Its capabilities
include simultaneous positive and negative variable amplitude outputs; single
or double pulse operation; internal or external triggering; synchronous or
asynchronous gating; and internal or external sine wave triggering. Each of
the two outputs deliver 2 watts into 50 ohm loads. All operating controls and
test connectors are on the front panel except the 115-230 line voltage selector
switch which is on the back.
1.2 REPETITION RATE
The repetition rate is continuously variable from 10 Hz to 10 MHz by
means of a six step decade selector switch and a fill-in vernier control for
either single or double pulse operation. Effective repetition rates to 20 MHz
may be set up in the double pulse mode by proper positioning of the second
pulse.
1. 3 EXTERNAL TRIGGER
Reliable triggering at any point on the input waveform between 0. 25
volts and 5 volts above (or below) its average dc level for positive (or
negative) going waveforms with a minimum duration of 30 nanoseconds at
frequencies from 0 to 10 MHz is obtained by proper selection of slope polarity
and level controls. Sine wave signals above 1 volt rms at frequencies of
50 Hz to 10 MHz may be used for external triggering. The input impedance
is greater than 2. 5k ohms and the maximum transient amplitude which may
be applied is :5 volts.
1.4 LINE VOLTAGE TRIGGER
The unit may be triggered from any point on the positive or negative
slope of the ac line voltage waveform for either internal or external (see 1. 3
above) operation. In both cases the trigger point is determined by the setting
of the slope level control. The trigger signal is supplied by the power trans—
former secondary for internal operation. To simulate triggering on the crest

of the sine wave where the rise time is less than the minimum required,
it is necessary to incorporate a suitable pulse delay setting.
1. 5 SINGLE PULSE
The instrument may be triggered manually by a pushbutton for one
cycle (single or double pulse) of output.
1. 6 GATED OPERATION
External gate signal levels more positive than +1 volt are required
to enable the main pulse outputs for either synchronously or asynchronously
gated modes. Levels greater than 10 volts may not be applied.
1. 6. l Synchronous Gating
The repetition rate generator circuit is disabled in this mode of
operation until the unit receives an external gating signal. The generator
turns off again when the signal is removed. This synchronizes the first
main pulse of the gated burst to the leading edge of the gating signal and
stops the pulse train when the signal turns off. Both trigger outputs are
also gated.
l. 6. 2 Asynchronous Gating
In this mode, the time delay circuit is disabled while the repetition
rate generator operates continuously. Both the main pulse output and the
reference trigger begin with the first cycle occurring after the application
of the gate for either external or internal triggering. The advanced trigger
output is not gated and is available as a clock pulse on internally triggered
operations .
1. 6. 3 Coincidence Gating
This mode of operation is achieved by combining external gating
with external triggering so that the main pulse outputs occur only when the
two are coincident.
l. 7 TRIGGER OUTPUTS
The trigger outputs are positive with an amplitude of 2 volts from a
50 ohm source impedance and a duration of approximately 50 nanoseconds.
1. 7.1 Advance Trigger
This trigger is available on internally triggered operations only and
occurs approximately 10 percent of the repetition rate period before the
reference trigger.
1. 7. 2 Reference Trigger
The reference trigger occurs approximately 30 nanoseconds after
1-2

the unit is triggered from an external source, or 10% of the repetition rate
period after the advance trigger on internally triggered operations.
1. 8 PULSE MODE
Single or double pulse operation is available.
1.8.1 Single Pulse
In single pulse operation one pulse per cycle occurs at the main
pulse outputs at the end of the delay period.
1. B. 2 Double Pulse
Two pulses per cycle occur at the outputs in this mode. One pulse
occurs approximately 30 nanoseconds after the reference trigger and the
second at a position determined by the pulse delay controls. The two pulses
are essentially identical in width, amplitude and polarity.
1. 9 PULSE DE LAY
The pulse delay (with respect to the reference trigger output) is
continuously variable by means of a six position decade switch and a
fill-in vernier control over a range of 30 nanoseconds to 10 milliseconds.
The maximum duty cycle is at least 70 percent.
1.10 PULSE WIDTH
The pulse width (at 50 percent point of rise and fall) is continuously
variable by means of a six position decade switch and a fill-in vernier control
over a range of 30 nanoseconds to 10 milliseconds. The maximum duty cycle
is at least 70 percent.
1.11 MAIN PULSE OUTPUT
Positive and negative main pulse outputs are provided simultaneously.
They are dc coupled to voltage sources with their baselines at ground
potential and are accessible through separate 50 ohm variable attenuators.
The source impedance is very low at maximum amplitude, increasing to
essentially 50 ohms at amplitudes of less than 5 volts. The amplitude controls
are continuously variable from 10 volts to less than 0. 5 volts when the outputs
are applied to 50 ohm loads.
1.12 PULSE OUTPUT COUNTDOWN
Main pulse outputs stably counted down from the trigger repetition
rate by ratios up to 100:1 are obtainable by setting the pulse delay controls
for a delay time that is greater than the trigger period. External or inter—
nal triggers received during the delay are held off. On countdown operation,
the reference trigger output occurs at the counted-down rate while the
advanced trigger which is available on internally triggered operation occurs
at the trigger rate.

1. 13 RISE AND FALL TIME
With a 50 ohm resistive load applied to the output, the main pulse
rise time is less than 5 nanoseconds and the fall time is less than 7 nano—
seconds.
1.14 JITTER
Repetition rate, delay and width jitter are less than 0.1 percent.
1. 15 WAVEFORM ABERRATION
Overshoot, undershoot, ring and top slope aberration are typically
less than 15 percent (with a maximum of 17 percent) at amplitudes greater
than 2 volts when the outputs are properly terminated by 50 ohm loads.
1.16 OUTPUT PROTECTION
Output stages will not be damaged by any combination of panel
control settings and will withstand short circuits to ground of any duration.
The unit is not rated for operation into loads at other than ground potential.
1. 17 OUTPUT MIXING
Multiple units may be diode mixed with no loss of amplitude when
the outputs are of the same polarity by means of the Type 2302 Pulse Mixer,
available as an accessory. Opposite polarity outputs may be resistor
mixed with a resultant loss of amplitude.
1. 18 OPERATING TEMPERATURE
The instrument is rated for operation in ambient temperatures of
0° to 50° c.
1. 19 POWER REQUIRED
Approximately 10 watts at 105—125 volts and 50-400 Hz ac is required
by the unit. All power supplies within the instrument are regulated against
line and load changes. A two-position slide switch mounted on the back panel
permits the unit to be operated from either 115 or 230 volt line sources.
1. 20 PHYSICAL CHARACTERISTICS
The cabinet is russet brown with brushed aluminum trim and has
removable top and bottom covers and tilt-up brackets for bench use. The
front panel is brushed aluminum finished with black etched and filled
markings and trim. The unit weighs approximately 8 pounds and is 3-1/2
inches high by 8—1/2 inches wide and 11 inches deep. Units may be rack
mounted by means of Type 1005 (single unit) or Type 1006 (double unit)
Rack Mounting Sets .

l
.21
ACCESSORIES
AVAILABLE
1.
21.1
Type
1005
Rack
Mounting
Set
This
standard
modular
relay
rack
panel
(19
inches
wide
by
3-1/2
inches
high)
permits
single
units
to
be
rack mounted.
1. 21. 2 Type 1006 Rack Mounting Set
Two instruments are mounted in this 19 inch wide, 3-1/2 inch high
standard size rack panel.
1.21.3 Type 2003 50 Ohm Termination
This characteristic impedance load may be used as a convenient
termination of either the output pulse in various test applications or as a
load
for
the
idle
output
to
avoid
distortion
interference
of
the
output
being
us
ed.
1.21.4 Type 2101 lnverting Transformer
This transformer is used to invert the positive trigger output (ad-
vanced
or
reference)
for
test
applications
requiring
a
negative
synchronous
pulse
output.
1.21. 5 Type 2302 Mixer Unit
Multiple unit outputs of the same polarity are conveniently mixed
with no loss of amplitude by this accessory-
l.21. 6 Type 2401 Variable Integrator
The application of the Model 101 puise generator with its fixed rise
time output pulses may be extended by the 2401 Variable Integrator which
provides a means of varying pulse rise and [all times.
1.21.7 Instruction Manuals
One instruction manual is supplied with each unit. Additional
manuals are available at $5.00 each.

SECTION II
OPERATING INSTRUCTIONS
Z. 1 GENERAL INFORMATION
The basic capabilities of the Model 101 Pulse Generator satisfy a
broad range of pulse test requirements. These consist of repetition rates
to 10 MHz, single or double pulse mode operation, 5 nanosecond rise time,
i10 volt output amplitudes, i250 millivolt trigger sensitivity and variable
pulse width and delay to 10 milliseconds. Flexible external gating and
triggering with countdown capability extends this usefulness, and 100021
coverage on delay and width timing control ranges provides extra convenience
of operation
The external gating capability makes synchronous, asynchronous or
coincidence gating possible. In the synchronous gate mode, the output pulse
train is synchronous with the leading edge of an externally applied gate wave-
form with negligible difference in the pulse waveform between the first and
last pulse in the gated burst.
In the asynchronous mode, the output pulse train is normally off while
the oscillator continuously provides advanced trigger outputs. Application
of an external gating signal enables the pulse outputcircuitry, beginning with
the first advanced trigger after the gate is applied and continuing until the
gate is removed. The reference trigger output is available during the pulse
train.
Coincidence gating is achieved by application of a gate pulse at the
gating input and a trigger source at the external trigger input. The 101
produces a pulse whenever the two are coincident.
The external trigger circuit utilizes slope level and polarity controls
and provides sensitivity of 250 millivolts for oscilloscope type triggering.
Synchronous countdown of external trigger is useful in applications
requiring frequency division. With the delay set greater than the period of
an external trigger, the output pulse rate is a subharmonic of the trigger
rate, counted down by a factor set by the delay control. Similar operation
may be secured by using the internal oscillator. The advanced trigger out—
put
occurs
at
the
oscillator
rate
and
the
reference
trigger
and
pulse
outputs
occur at the subharmonic rate.
The
repetition
rate
selector
switch
permits
the
unit
to
be
triggered
from
any
point
on
the
positive
or
negative
slope
of
the
ac
line
voltage
wave—
form. This may be applied to power control circuity design using SCR's
thyratrons, etc.

The
1000:1
coverage
on
delay
and
width
timing
control
ranges
made
possible
by
a
unique
circuit
design
allows
extremely
wide
vernier
coverage
with
little
or
no
sacrifice
in
resolution.
2.2
DESCRIPTION
OF
CONTROLS
AND
CONNECTORS
2. 2. 1 Power Switch
WARNING
Do not connect the unit to a line
source nor turn it on before veri-
fying that the 115-230 line voltage
selector switch is in the correct
position.
to
the
transformer
primary
within
the
instrument
and
lights
the
red
pilot
lamp
when
it
is
turned
ON.
2. Z. Z Repetition Rate Control
The
larger
eleven
position
REPETITION
RATE
knob
selects
either
the
trigger
mode
or
the
repetition
rate
range
and
the
smaller
vernier
knob
provides continuously variable frequency control for each repetition rate
range setting.
-
1
The
POWER
toggle
switch
connects
or
disconnects
ac
input
voltage
There are six repetition rate ranges in decade steps. The instru-
ment
will
be
set
to
the
repetition
rate
indicated
by
the
selector
knob
position when the vernier knob is fully clockwise.
The EXT TRIG SLOPE (+) and (-) pOSitions provide for instrument
triggering from an external source by either a positive or negative going
waveform.
In the LINE SLOPE positions the unit is triggered from either the
positive or negative slope of the ac line voltage waveform.
The SINGLE PULSE position of the REPETITION RATE selector
knob allows the instrument to be triggered manually by the red SINGLE
PULSE button for one cycle of output.
The setting of the TRIGGERING LEVEL control determines the ampli-
tude point of either a positive or negative signal that will operate the unit for
both external and line voltage triggering.
A BNC connector (TRIGGER INPUT) is provided for the input signal
when the instrument is triggered from an external source.
2.2. 3 Gate Mode
The three position GATE MODE slide switch determines whether the
2-2

main
pulse
output
will
be
continuous
(in
the
NON—GATED
position)
or
will
occur
in
gated
bursts
as
controlled
by
an
externally
applied
gating
signal.
In
the
two
gated
modes,
internal
circuits
are
disabled
and
main
output
pulses
occur
only
when
a
gate
signal
is
applied
to
the
unit.
The
repetition
rate
generator
circuit
is
disabled
when
the
GATE
MODE
switch
is
in
the
SYNC
position.
The
first
main
pulse
of
a
gated
burst
in
this
mode
is
synchronized
to
the
leading
edge
of
the
gating
signal.
Both
trigger
outputs
are
also
gated.
In
the
ASYNC
position
the
main
output
is
held
off
by
disabling
the
time
delay
circuit
and
the
repetition
rate
generator
is
uninterrupted.
Both
the
main
pulse
output
and
the
reference
trigger
begin
with
the
first
cycle
occurring
after
the
application
of
the
gate
for
either
internal
or
external
triggering.
The
advanced
trigger
output
is
not
gated
and
is
available
as
a
clock
pulse
on
internally
triggered
operations.
The
BNC
connector
labeled
ENABLING
GATE
INPUT
is
provided
for
the
gate
signal
input
when
the
unit
is
operated
in
either
of
the
gated
modes.
2. 2.4 Trigger Outputs
Two
BNC
connectors
labeled
TRIGGER
OUTPUT
provide
for
advanced
and
reference
trigger
outputs
of
approximately
50
nanoseconds
duration.
The
ADVANCED
trigger
is
available
on
internally
triggered
operations
only
and
occurs
approximately
10
percent
of
the
pulse
period
before
the
reference
trigger.
The
REFERENCE
trigger
occurs
approximately
30
nanoseconds
after
the
unit
is
triggered
from
an
external
source.
2.2. 5 Pulse Mode Switch
Single
or
double
pulse
operation
is
selected
by
the
two
position
PULSE
MODE
switch.
In the
SGL
position
one
pulse
per
cycle
occurs
at
the
outputs
following
the
reference
trigger
by
a
period
determined
by
the
pulse
delay
controls.
Two
identical
pulses
occur
when
the
slide
switch
is
in
the
DBL
position
with
the
second
pulse
at
a.
position
determined
by
the
pulse
delay
controls
and
the
first
pulse
approximately
30
nanoseconds
after
the
reference
trigger.
2.2. 6 Pulse Delay Control
The larger six position PULSE DELAY knob selects the range in decade
steps
and
the
smaller
vernier
knob
provides
continuously
variable
control
for
each
position
for
delay
times
ranging
from
30
nanoseconds
to
10
milliseconds.
The
instrument
will
be
set
to
the
delay
indicated
by
the
selector
knob
position
when the vernier knob is fully clockwise.
2.2. 7 Pulse Width Control
The larger six position PULSE WIDTH knob selects the range in decade
steps
and
the
smaller
vernier
knob
provides
continuously
variable
control
for
each position for pulse widths ranging from 30 nanoseconds to 10 milliseconds.
The instrument will be set to the pulse width indicated by the selector knob
position when the vernier knob is fully clockwise.
2—3

1
a
Z.
2.
8
Amplitude
Control
The
POSITIVE
and
NEGATIVE
AMPLITUDE
knobs
provide
continuously
variable
control
from
10
volts
to
less
than
0.
5
volts
for
the
simultaneously
occurring
positive
and
negative
main
output
pulses.
For
both
outputs
the
baseline
is
at
ground
potential
and
the
source
impedance
is
very
low
(approximately
50
ohms
or
less).
The
POS
OUTPUT
ENC
connector
couples
the
variable
parameter
positive
pulse
to
an
external
load.
The
NEG
OUTPUT
BNC
connector
couples
the
variable
parameter
negative
pulse
to
an
external
load.
The
GRD
jack
provides
access
to
the
instrument
ground
for
test
connections.
2. 3 OPERATING PROCEDURE
2
3.
1
Equipment
(or
equivalent)
Required
a.
Tektronix
Model
661
Sampling
Oscilloscope.
b.
Tektronix
Model
543
Real
Time
Scope
with
CA
Plug-in
Unit.
c,
Datapulse
Model
101
Pulse
Generator.
d.
Datapulse
Type
2003
Power
Termination.
2. 3. 2 Preliminary Settings
WARNING
Do not connect the unit to a line
source nor turn it on before veri-
fying that the 115-230 line voltlge
selector switch is in the correct
position.
a.
Turn
the
REPETITION
RATE
selector
knob
to
the
O.
1
MHz
position
and
the
vernier
knob
fully
clockwise.
b.
Turn
the
PULSE
DELAY
selector
knob
to
the
0.
l‘pS
position
and
the
vernier
knob
fully
clockwise.
c.
Turn
the
PULSE
WIDTH
selector
knob
to
the
l.
0
uS
position
and
the
vernier
knob
fully
clockwise.
d.
Turn
both
AMPLITUDE
knobs
fully
clockwise
to
the
10V
positions.
I
2-4

I e. Set the GATE MODE switch to the NON—GATED position.
f. Set the PULSE MODE switch to the SGL position.
g. Connect the Datapulse Type 2003 Power Termination or a suitable
50 ohm, 2 watt (minimum) load to the POS OUTPUT jack.
2. 3. 3 Main Pulse Output
a. Set the front panel controls to the preliminary settings in step
2.3.2 (above).
b. Turn the POWER switch ON. The pilot lamp should light.
c. Synchronize the sampling oscilloscope from the REFERENCE
TRIGGER OUTPUT, set the sweep for 0.2 pS/cm and the
amplitude for 2V/cm.
d. Monitor the positive output at the terminating load with a high
impedance probe. A single flat topped pulse 5 cm wide and 5 cm
high with near vertical rise and fall time should appear on the
oscilloscope.
e. Turn the POSITIVE AMPLITUDE control counterclockwise and
note that the amplitude decreases without any noticeable effect
on waveshape down to 2 volts. Return the AMPLITUDE to the
10V position.
f. Disconnect the load from the POS OUTPUT and reconnect it to
the NEG OUTPUT. The negative pulse should look like the
positive pulse inverted on the oscilloscope.
g. Repeat step e (above) for the NEGATIVE AMPLITUDE control.
h. Turn the PULSE WIDTH vernier counterclockwise. The pulse
width should follow the control and decrease successively.
Return the vernier to its clockwise position.
i. Vary the PULSE DELAY vernier. The pulse should move
smoothly left or right, following the control movements.
._ 2.3.4 Double Pulse Mode
I I' a. Turn the unit on with its controls set to the preliminary settings
’ ofstep2.3.2.
b. Set the sampling oscilloscope sweep to 1.0 us /cm and synchronize
' it to the ADVANCED TRIGGER OUTPUT.
c. Set the PULSE MODE switch to the DBL position.

d.
e .
Turn
the
PULSE
DELAY
selector
to
the
10
uS
position
and
its
vernier
fully
counterclockwise.
Turn
the
PULSE
DELAY
vernier
clockwise
noting
that
a
second
pulse
appears
on
the
oscilloscope
and
moves
smoothly
from
left
to
right
as the
vernier
is
turned
clockwise.
Vary
the
PULSE
WIDTH
vernier.
Both
pulses
should
change
successively
and
follow
the
control
variations.
2.3. 5 Single Cycle Operation
a.
b.
d.
(D
Monitor
the
output
with
the
real
time
oscilloscope
synchronized
to
the
REFERENCE
TRIGGER
OUTPUT
with
its
sweep
set
to
O.
l
MS/cm
and
its
amplitude
set
to
5V/cm.
Set
the
GATE
MODE
switch
to
the
NON-GATED
position
and
the
PULSE
MODE
switch
to
SGL.
Switch
the
REPETITION
RATE
selector
to
the
SINGLE
PULSE
position.
Turn
the
PULSE
DELAY
to
10
uS
and
its
vernier
fully
counter-
clockwise.
Set the PULSE WIDTH to 0. 1 MS with its vernier fully clockwise.
Turn the AMPLITUDE to a convenient setting and switch the
POWER ON.
Press the SINGLE PULSE button and verify that one pulse only
appears on the oscilloscope each time the button is pressed.
2.3. 6 External Trigger Operation
a.
Switch the REPETITION RATE selector to the (+) EXT TRIG
SLOPE position and the PULSE WIDTH to 10 uS but retain the
other control settings and oscilloscope connections of step 2. 3.5.
Connect the external trigger source (Datapulse 101 or equivalent)
to the TRIGGER INPUT jack and set its REPETITION RATE to
10 KHz with vernier fully clockwise, its PULSE DELAY to
minimum and its PULSE WIDTH to approximately 30 nanoseconds.
Turn both the trigger source and the unit under test on.
Adjust the TRIGGERING LEVEL control until several pulses
appear on the oscilloscope.
Turn the external trigger source REPETITION RATE vernier
counterclockwise and note that the number of pulses on the oscillo-
scope reduces successively as the trigger repetition rate is
decreased.
2-6

Switch the REPETITION RATE selector to the (-) EXT TRIG
SLOPE, the external trigger source to its negative output, and
repeat steps d and e (above).
2. 3. 7 Line Slope Triggering
a.
b.
Turn the REPETITION RATE selector to the (+) LINE SLOPE
position but retain all other control settings of step 2. 3. 6.
Set the oscilloscope sweep to 5 MS/cm and synchronize it to the
ac line (by the oscilloscope sync control).
Turn the unit on and vary the TRIGGERING LEVEL control noting
that pulses appear on the oscilloscope, then shift and disappear as
the control is varied.
Switch the REPETITION RATE selector to the (-) LINE SLOPE
position and repeat step c.
2. 3. 8 Gating Operation
a.
b.
Set the REPETITION RATE selector to 0. 1 MHz with its vernier
fully clockwise.
Turn the PULSE DELAY selector to O. 1 us and its vernier fully
counterclockwise.
Switch the PULSE WIDTH selector to l. 0 uS with its vernier
fully clockwise.
Set the
PULSE
MODE
switch
to
SGL
and
the
POSITIVE
AMPLITUDE
to
the
10V
position.
Set the GATE MODE switch to the SYNC position.
Connect
an
external
gating
source
(Datapulse
101,
or
equivalent)
to
the
ENABLING
GATE
INPUT
jack.
Set the
gating
signal
REPETITION
RATE
to
1.
0
KHz,
PULSE
DELAY
to
10
uS and
PULSE
WIDTH
to
0.
1
MS
with
all
verniers
fully
clockwise,
and
adjust
its
POSITIVE
AMPLITUDE
to
2
volts.
CAUTION
Do not exceed the maximum permis~
sible signal level of 10 volts.
Use
the
real
time
oscilloscope
with
its
dual
trace
attachment
to
monitor
both
the
gating
signal
(upper
trace)
and
the
POSITIVE
OUTPUT
of
the
unit
being
tested
(lower
trace).
Synchronize
the
oscilloscope
with
the
gating
signal
generator
REFERENCE
TRIGGER
OUTPUT
and
set
its
sweep
to
20
uS/cm.
Adjust
the
amplitude
of
2-7

the upper trace to lV/cm and the lower trace to SV/cm.
With both the unit under test and the gating signal generator turned
on, several pulses should appear on the lower trace synchronized
with the gate pulse on the upper trace.
Vary the gate signal PULSE WIDTH vernier and note that the pulses
on the lower trace disappear successively as the gate pulse width
(upper trace) is reduced.
Monitor the ADVANCED TRIGGER OUTPUT of the unit under test
on the upper trace of the oscilloscope and synchronize the oscillo-
scope to the REFERENCE TRIGGER OUTPUT of the unit under test.
Set the oscilloscope sweep to Z uS/cm and the amplitude of the
upper trace to ZV/cm.
Set the REPETITION RATE selector to l. 0 MHz with its vernier
fully clockwise, the PULSE WIDTH vernier fully counterclockwise,
and the GATE MODE switch to ASYNC.
Set the gating signal REPETITION RATE to 10 KHz and PULSE
DELAY and PULSE WIDTH to 10 uS with all verniers fully clock-
wise.
Vary the gate signal PULSE WIDTH vernier and note that the
pulses on the lower trace disappear successively as the vernier is
turned counterclockwise. The advance trigger pulses on the upper
trace are not affected.

SECTION III
THEORY OF OPERATION
3. 1 GENERAL DESCRIPTION
Refer to the block diagram for the following discussions.
A clock pulse (1 C) with a variable repetition rate is generated
by the rate oscillator and applied to the trigger multivibrator which
produces the system clock pulse (1 D) for the pulse generator. The
oscillator output is also applied to the advance trigger amplifier to pro—
vide a synchronous “zero" time reference trigger output for internally
triggered operations. When the rate oscillator is turned on by the
repetition rate selector in any of the six range positions, its output
governs the operation of the remaining circuits through its control of the
trigger multivibrator.
When
the
repetition
rate
selector
is
in
either
of
the
two
external
trigger
or
the
two
line
trigger
positions,
the
external
trigger
amplifier
is
turned
on
and
its
output
(1
B)
controls
the
system
clock
pulse.
No
advance
trigger
occurs
because
the
rate
oscillator
is
turned
off.
A sample of the ac line voltage is taken from the power trans-
former secondary for the line trigger positions. A pushbutton trips the
trigger
multivibrator
directly
for
one
cycle
of
output
when
the
repetition
rate switch selects single pulse operation.
The main output will be continuous in the non-gated mode of
operation
but
will
be
interrupted
and
will
occur
in
bursts
in
either
of
the
two
gated
modes
of
switch
$2.
The
AND
gate
permits
the
delay
multi—
vibrator
to
be
driven
continuously
by
the
system
clock
or
to
be
turned
on
and off by gate signals from the gate emitter follower.
In
the
synchronous
mode
the
external
gate
amplifier
controls
the
rate
oscillator
and
turns
it
on
and
off.
The
main
output
pulse
train
is
synchronized
with
the
leading
edge
of
the
gated
waveform
and
is
turned
off
at
the
trailing
edge.
In
the
asynchronous
mode
the
output
of
the
external
gate
amplifier
is
applied
to
the
gate
emitter
follower
to
control
the
delay
multivibrator
rather
than
the
rate
oscillator.
The
signal
from
the
gate
emitter
follower
gates
the
signal
from
the
trigger
multivibrator
through
the
AND
gate
to
the
delay
multivibrator.
This
permits
the
rate
oscillator
to
provide
a
continuous
output
of
advance
trigger
pulses
and
causes
the
output
pulse
train
to
begin
with
the
first
advance
trigger
after
the
gate
is
applied
and
to

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continue
until
the
gate
is
removed.
The
reference
trigger
output
is
gated
in
both
modes
of
operation.
Both
the
leading
and
trailing
edges
of
the
delay
multivibrator
output
waveform
are
differentiated
to
produce
trigger
pulses
separated
in
time
by
the
delay
period.
These
are
applied
to
the
reference
trigger
amplifier
and
to
the
width
multivibrator
through
the
OR
gate.
Switch
S71
disconnects
the
leading
pulse
from
the
input
to
the
width
multivibrator
(l
E)
in
the
single
pulse
mode
so
that
the
main
output
is
a.
single
pulse
separated
in
time
from
the
reference
trigger
output
by
the
delay
period.
In
the
double
pulse
mode,
the
width
multivibrator
is
turned
on
twice
during
each
cycle
by
the
two
trigger
pulses.
The
first
pulse
occurs
approx-
imately
30
nanoseconds
after
the
reference
trigger
output
and
the
second
at
a
point
determined
by
the
pulse
delay
controls.
Both
pulses
are
essentially
identical.
The
pulse
width
in
either
mode
is
determined
by
the
period
of
the
width
multivibrator.
The output of the width multivibrator (2 A) is us ed by the output
drivers
to
generate
a
signal
(2
C)
to
drive
the
positive
output
amplifier.
An
inverted
version
(2
B)
generates
the
signal
(2
D)
used
to
drive
the
negative
output amplifier.
Variable attenuators provide output pulse amplitude control. The
overload protection circuits are current sensitive and turn off their
respective power supplies when either output is overloaded.

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3.2 CIRCUIT DESCRIPTION
Refer to the schematic diagram for the following discussions.
3 2.1 Repetition Rate Oscillator
The internal rate oscillator is an emitter coupled multivibrator
with high level positive feedback for ac provided by the timing capacitors
C6 through Cll. This circuit supplies a free-running basic rate that
governs the remaining circuits and provides system clock output pulses.
In addition, it has the capability of synchronously starting oscillations
that begin at the leading edge of a control gate and continue until the gate
is removed. The oscillator circuit consists of transistors Q2, Q3, and
Q4 and their related circuit components.
To trace the cycle of operation, assume that Q4 is cut off and Q2
is conducting; the waveform at the base of Q4 will then be rising exponentially
toward ground. The emitter of Q4 will be held near ground by the conducting
emitter of Q2 and when the base of Q4 reaches ground, Q2 will start to cut
off. The resulting positive step at the collector of OZ will be transferred
through emitter follower C3 and the timing capacitor (C6 through C11) to the
base of Q4. QB provides a low impedance discharge path for the timing
capacitor through diode CR3 to ground. C4 will regeneratively turn on
while QZ is turned off but the circuit will remain in this condition for only a
short time because of the low impedance of CR3. It will again become regen-
eratively unstable and Q4 will be cut off when the timing capacitor discharges
through CR3, starting the cycle over again.
The collector of Q4 provides an isolated output that does not affect
the timing circuitry and is used to drive the trigger multivibrator (CR50 and
08) and the advance trigger amplifier (Q7). The positive step at the collector
of Q4, when it is cut off operates the trigger multivibrator and the negative
step, when Q4 again conducts drives the advance trigger amplifier. The
negative step always appears somewhat before the turnoff of Q4 and is present
whenever the rate oscillator is running.
3, Z. 2 External Gate Amplifier
Q1 is a buffer amplifier stage which inverts the external gate and
provides the standardized output to gate the rate oscillator and the delay
multivibrator. The base to emitter drop of Q1 sets the gate amplitude
requirement and base resistor R2 provides input impedance as well as
protection from overdrive.
In the asynchronous gating mode, the output of ()1 drives Q9 which
is used to gate the delay multivibrator. The rate oscillator is not gated.
In synchronous gating, the rate oscillator is stopped at a point in its
cycle just before the turn off of Q4 would normally Occur and is held in this
condition by the current through resistor R4 and diode CR1. The application
of a gate signal drives the collector of Ql abruptly negative and allows Q4 to
turn off by stopping the current flow in R4 and CR1 that was holding its base
3-4

LLLLale—‘L’LL’L
positive,
The
sudden
drop
at
the
collector
of
Q1
also
produces
a
negative
step
through
R7
to
the
collector
of
OZ
comparable
to
the
step
that
turns
02
on
during
normal
oscillations.
This
causes
the
oscillator
to
start
promptly
at
the
leading
edge
of
the
gate,
just
as
though
it
had
been
running
before
the
gate
was
applied.
3 2, 3 Advance Trig er Amplifier
The advance trigger amplifier Q7 is designed to differentiate the
output
of
the
rate
oscillator
by
means
of
its
small
emitter
bypass
capacitor
C55. It uses the negative going edge of pulses from Q4 to produce positive
triggers
at
its
collector.
These
are
terminated
in
a
51
ohm
resistor
R62,
and applied to the advance trigger output jack.
3. 2. 4 Trigger Multivibrator
The
positive
going
output
from
Q4
is
applied
through
diode
CRSZ
to
the
trigger
multivibrator
circuit
consisting
of
CR50,
Q8
and
their
related
circuit
components.
CR50
is
a
5
milliampere
tunnel
diode
functioning
as
a
high
speed
Schmidt
Trigger
circuit.
The
current
swing
available
from
Q4
is
determined
by
the
circuit
parameters
and
is
assured
to
be
more
than
the
swing
required
to
trip
CR50
from
its
low
voltage
to
its
high
voltage
condition
and
back
again
as
the
rate
oscillator
cycles.
At each positive transition of CR50 a fast step is applied to DB,
which serves as an output pulse shaper for the trigger multivibrator. Q8
is biased by resistors R54, R55, and R57 in the on state with enough current
for high band width operation. By virtue of the small emitter bypass capacitor
C53, a sharp differentiated pulse appears at the collector of QB and is used to
trigger the delay multivibrator. Q8 also serves to prevent the reaction of the
delay multivibrator from reaching the rate generator.
3. 2.. 5 Delay Multivibrator
The delay multivibrator consists of transistors Q10 and Qll and their
related circuit components. These transistors form a complementary one-
shot multivibrator whose pulse width determines the delay interval. In order
to achieve the high ratio of delay to recovery time, the transistors are
arranged so that both are normally conducting and during the delay period,
both are turned off. At the end of the delay period, both conduct heavily,
providing a short recovery period and permitting the delay period to be almost
as long as the period of the rate oscillator.
A
negative
trigger
from
the
trigger
multivibrstor
applied
tothe
base
of
Qll
through
diode
CR51
starts
to
cut
Qll
off.
The
resulting
positive
waveform
at
the
collector
of
Qll
is
applied
to
the
base
of
010
cutting
010
off
and
causing
its
collector
to
go
negative.
This
adds
to
the
negative
signal
at
the
base
of
Qll,
completing
its
turn
off
and
causing
011
to
block
the
negative
signal
from
the
trigger
source.