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Model
2001
CIRCUIT DESCRIPTION
positive, full output is retained (a diode opens the vernier
ground connection) producing a nearly constant retrace
time.
For triggered modes, the negative threshold of the hysteresis
switch is shifted out of the way by a diode and resistor con-
nected through 0 1 4 or through S102D, when in "line''
position. The integrator will now continue its negative ramp
until
it
i s stopped by a clamp circuit turned on by a com-
parator. The integrator output i s now held at this level un-
less a trigger is applied to the hysteresisswitch. A trigger
cannot flip the hysteresis switch until this clamp level is
reached because the triggers must pass through an amplifier
which is gated off until the clamp comparator ( 0 9 ) con-
ducts.
Triggers are prevented from reaching the hysteresis switch
(pin 6) by a voltage at pin 1, which causes comparator 0 8
to open FET switch 014. The primary function of the vol-
tage at pin 1 is to shift the clamp comparator input out of
the way to allow free-running oscillations.
Since the integrator is an inverting amplifier, and both input
(pin
7 )
and output (pin 8) are available, a feedback resistor
network allows the SWEEP TlME vernier, R 102, to be used
as a dc level shifter in the manual mode. A non-inverting
amplifier consisting of Q6, 0 7 and Q19, with a gain of
2,
provide a 32 volt peak-to-peak wave output which is used for
sweep drive. This output is divided by R 18 and R53 t o pro-
vide a horizontal drive of about 16 volts peak-to-peak at an
impedance of about 23K ohms.
A centering adjustment (R4 1) provides a dc level adjustment
of the integrator and horizontal outputs (pin 8, pin 12, and
pin 11) by shifting both positive and negative thresholds of
the hysteresis switch. A size adjustment (R45) provides an
amplitude adjustment by effectively varying the size of the
hysteresis window.
Symmetry of trace and retrace time
(for equal positive and negative input voltages t o the inte-
grator) is established by adjusting the integrator balance
control R7. This adjustment also affects the manual mode
centering and the sweep period for fully counterclockwise
rotation of the SWEEP TlME vernier.
The four sections of the SWEEP TlME selector switch pro-
gram the M l H module. The functions of each section are
listed below :
Section A
Integrator input selector
Section B
Clamp level shift and routing switch
disconnect
Section C
Trigger source selector
Section D
Line trigger routing, and hysteresis
switch hold.
Circuit operation as modified by the switch positions may
be understood by considering the MANUAL, VARIABLE
RATE, and LINE positions one at a time.
MANUAL POSITION
Section A.
A feedback resistor R 113 is connected from
output (pin 8) to input (pin 7) of the integrating amplifier,
converting it to an inverting dc amplifier. Resistor R 114
shifts the amplifier output dc level t o -8 volts for zero input
voltage to R104. When the SWEEP TlME vernier control
R102 i s fully clockwise, the negative input voltage t o R 104
is sufficient to shift the output voltage to +8 volts dc.
Section B. The clamp is disabled in this position by apply-
ing +18V t o pin I, causing the hysteresis switch input to be
disconnected from any internal source of triggers by open-
ing the routing switch 0 1 4 (since Q8 is turned off). The
shift bias is disconnected when 0 1 4 is open.
Section C.
The trigger input point pin 4 i s grounded.
Section D. The hysteresis switch is held in one state by
applying -18 volts to its input through a 33K ohm resistor.
This causes the output t o be negative (this bistable circuit is
a positive feedback amplifier) providing the proper polarity
to R102 and preventing blanking of the RF output.
VARIABLE RATE POSITIONS
Section A. Proper integrator input resistors are selected in
decade increments in these positions, R 105
-
R 108.
Section B. The clamp is disabled and triggers are held off
unless the "pull trigger" switch is opened, removing + I 8
volts.
Section C. Two trigger sources are connected t o pin 4; an
external trigger from REMOTE jack J101-7 and triggers
from the Front Panel momentary TRIG switch S103.
Section D. No connection is made t o pin 6 in any of the
four variable rate positions.
LINE POSITION
Section A. The proper value integrating resistor i s selected,
by-passing the SWEEP TlME vernier, t o produce equal
sweep and retrace periods.
Section B. Clamping, works in this position independently
of the "pull trig" switch.
Section C. The line rate square wave from the power supply
is connected t o the trigger input.
Model 2001
positive, full output is retained (a diode opens the vernier
ground connection) producing a nearly constant retrace
time.
For triggered modes, the negative threshold of the hysteresis
switch is shifted out of the way by a diode and resistor con-
nected through 014 or through S102D, when in "line"
position. The integrator will now continue its negative ramp
until it is stopped by a cfamp circu it turned on by a com-
parator. The integrator output is now held at this level un-
less a trigger is applied to the hysteresis switch. A trigger
cannot flip the hysteresis switch until this clamp level is
reached because the triggers must pass through an amplifier
which is gated off until the cfamp comparator (09) con-
ducts.
Triggers are prevented from reaching the hysteresis switch
(pin 6) by a voltage at pin 1, which causes comparator 08
to open FET switch 014. The primary function of the vol-
tage at pin 1 is to shift the clamp comparator input out of
the way to allow free-running oscillations.
Since the integrator is an inverting amplifier, and both input
(pin 7) and output (pin 8) are available, a feedback resistor
network allows the SWEEP TIME vernier, R 102, to be used
as a dc level shifter in the manual mode. A non-inverting
amplifier consisting of 06,07 and 019, with a gain of 2,
provide a 32 volt peak-to-peak wave output which is used for
sweep drive. This output is divided by R 18 and R53 to pro-
vide a horizontal drive of about 16 volts peak-to-peak at an
impedance of
~bout
23K ohms.
A centering adjustment (R41) provides a dc level adjustment
of the integrator and horizontal outputs (pin 8, pin 12, and
pin 11) by shifting both positive and negative thresholds of
the hysteresis switch. A size adjustment (R45) provides an
amplitude adjustment by effectively varying the size of the
hysteresis window.
Symmetry of trace and retrace time
(for equal positive and negative input voltages to the inte-
grator) is established by adjusting the integrator balance
control R7. This adjustment also affects the manual mode
centering and the sweep period for fully counterclockwise
rotation of the SWEEP TIME vernier.
The four sections of the SWEEP TIME selector switch pro-
gram the
M
1
H
module. The functions of each section are
listed below:
Section A
Section B
Section C
Section D
I ntegrator input selector
Clamp level shift and routing switch
disconnect
Trigger source selector
Line trigger routing, and hysteresis
switch hold.
CIRCUIT DESCRIPTION
Circuit operation as modified by the switch positions may
be understood by considering the MANUAL, VARIABLE
RATE, and LINE positions one at a time.
MANUAL POSITION
Section A.
A feedback resistor R 113 is connected from
output (pin 8) to input (pin 7) of the integrating amplifier,
converting it to an inverting dc amplifier. Resistor R 114
shifts the amplifier output dc level to -8 volts for zero input
voltage to R 104. When the SWEEP TIME vernier control
R 1 02 is fu lIy clockwise, the negative input voltage to R 104
is sufficient to shift the output voltage to +8 volts dc.
Section B. The clamp is disabled in this position by apply-
ing + 18V to pin 1, causing the hysteresis switch input to be
disconnected from any internal source of triggers by open-
ing the routing switch 014 (since 08 is turned off). The
shift bias is disconnected when 014 is open.
Section C.
The trigger input point pin 4 is grounded.
Section D.
The hysteresis switch is held in one state by
applying -18 volts to its input through a 33K ohm resistor.
This causes the output to be negative (this bistable circuit is
a positive feedback amplifier) providing the proper polarity
to R 1 02 and preventing blanking of the R F output.
VARIABLE RATE POSITIONS
Section A. Proper integrator input resistors are selected in
decade increments in these positions, R 105 - R 1 08.
Section B. The clamp is disabled and triggers are held off
unless the "pull trigger" switch is opened, removing +18
volts.
Section C. Two trigger sources are connected to pin 4; an
external trigger from REMOTE jack
J
101-7 and triggers
from the Front Panel momentary TRIG switch S103.
Section D.
No connection is made to pin 6 in any of the
four variable rate positions.
LINE POSITION
Section A. The proper value integrating resistor is selected,
by-passing the SWEEP TIME vernier, to produce equal
sweep and retrace periods.
Section B. Clamping, works in this position independently
of the "pull trig" switch.
Section C. The line rate square wave from the power supply
is connected to the trigger input.
4-5
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