Tektronix 7B10 Instruction Manual page 30

Theory
of
Operation
-7B10
GATE
GENERATOR
The Gate Generator
stage provides
an auto enable gate
to
the Logic
circuits
(diagram
3),
and
a
Sweep
Start
Gate
and Z Axis Gate (unblanking)
to
the
Sweep
Generator
circuit
(diagram
4).
Refer
to
Figure
3-2
for a
timing
diagram
of
the
Gate Generator
functions.
When
an adequate trigger signal
is
applied
to
U144-pins
5
and 8 and
when U144
is
enabled
(pin
2
is
LO), a
HI
level
is
produced
at
U1 44-pin
15 and
a
LO
level
is
produced
at
U1 44-pin
16.
The
HI level
from U1 44-pin
1
5
is
coupled through
emitter
follower
0184
and J200-2
into
the Logic
circuit
(diagram
3)
to indicate that a triggering signal
has been
received
The
Logic
circuit
(diagram
sets
the
Auto
Drive
at
J200-3
HI,
turning
off
0160.
Simultaneously, the
LO
level at
U1 44-pin
1
6 gates comparator
01 74-01
64.
The
collector
of
0164
rises HI
to
provide
a
sweep
start
gate
at
J200-5
and
the
collector of
0174
falls
LO
to
provide
a
Z-Axis
gate (unblanking)
at
J200-4
In
the
absence
of
a trigger signal
at
U1 44-pins
5
and
8,
pm
15
is
set
LO
and
pin
16
is
set HI.
The
LO
level
from
U1 44-pin
15
is
coupled through J200-2
to
the Logic
circuit
(diagram
to indicate
the
absence
of a triggering
signal.
The
Logic
circuit
provides
a
LO-level auto
drive
pulse
through
J2CXD-3
to
the
base
of
0160.
This
LO
level
gates the
comparator (0160 and
0174).
The
collector
of
0160
rises
high
to
provide
a
sweep
start
gate
and
the
collector
of
0174
falls
LO
to
provide
a
Z-Axis
Gate
(unblanking)
at
J200-4
LOGIC
The
Logic circuit controls
the
sweep modes
and
associated functions
of
the
time-base
unit (eg.,
sweep
display, hold
off,
auto sweep,
single
sweep,
etc).
The
Logic
circuit
also
generates
control signals
for
the
mainframe.
AUTO MODE
OPERATION
WITH TRIGGER SIGNAL
GATE
U144 PIN
3
GATE
U144 PIN 4
TRIG SENSE
GATE
J200
2
AUTO
DRIVE
J200-3
Z-AXIS
GATE
J2004
SWEEP START
GATE
J
200-5
I
I
! !
I
AUTO MODE OPERATION
WITHOUT TRIGGER
SIGNAL
>
I
I
I
I I
n
I
!
1
i
(1986 63)?316 13
Fig.
3*2.
Timing diagram
for
Gate Generator
stages
Q160, Q164. and Q174.
3-7