Circuit
Description—
Type
3B5
Slope
Multivibrator
The
Slope
Multivibrator,
Q75 and
Q85,
selects
the
Slope
Comparator
output
signal which
triggers
the
sweep.
This
is
accomplished
by
forward biasing
either
D66
or
D96.
Q75
and
Q85
are
connected
as
a
bistable
multivibrator.
For posi
tive
slope
triggering,
Q85
is
biased
off
and
Q75
is
con
ducting.
Since
the current
flow
through
R82
is
reduced
with
Q85
off,
the
voltage
level
at
the
collector of
Q85
rises
positive.
D82
is
reverse
biased and
the
voltage
across
B82,
+
SLOPE
indicator,
ignites
it.
Meanwhile,
on
the
Q75
side
of
the
multivibrator,
the
emitter
level
is
at
about
—
7
volts
as
established
by
zener diode D86.
The
base
level estab
lished
by
the
voltage
divider
R74-R75-R99
from
—12.2
volts
to
ground
is
positive
enough
(less
negative)
to
bias
Q75 on
and
D72
is
forward
biased.
The
collector
current of Q75
through
R72
pulls
the
collector
more
negative
and
B72,
—
SLOPE
indicator, is
held
off.
The
negative
voltage
level
at
the
collector
of Q75 reverse biases
D66
through
D65.
This
blocks the
inverted
trigger
signal
at
the
collector
of
Q74
from being
passed on
to the
Trigger
Shaper
stage.
At
the same
time
D96
is
forward
biased
through
D95
by
the
—
2
volt
level at
the
cathode
of
D95
established
by
divider
R74-R75-R99.
With
D96
forward
biased,
the
trigger
signal
at
the
collector
of
Q84
is coupled
to
the Trigger
Shaper
stage
to
provide
positive-slope
triggering.
For
negative-slope
triggering,
conditions
are
reversed.
Q75
is
off
and
Q85
is
conducting.
The
collector of
Q75
rises
positive
and
B72,
—SLOPE
indicator, is
turned
on.
D72
is
reverse
biased
and
the
less
negative
voltage
at the cathode
of
D65 established
by
divider
R69-R71-R85-R84
forward
biases
D66
through
D65.
The
inverted
trigger
signal
at
the
collector
of
Q74
passes
to the
Trigger
Shaper
stage. Q85
is
held
in
conduction by
a
less
negative
voltage at its
base
established by
the
voltage
divider
R69-R71-R84-R85 from
—
12.2
volts
to
ground.
With
Q85
conducting, its
collector
goes
negative
and
B82,
+
SLOPE
indicator,
is
held
off.
The
negative
level
at
the
collector
of
Q85
reverse
biases
D96
through
D95
and
D82
to
block
the trigger
signal from
Q84.
Q75
is
held
off
by
a
level
of about
—
6
volts
at
its
base
established
by
divider
R74-R75
from
—12.2
volts to the
collector
of
Q85.
When
the
CHANGE
SLOPE
pushbutton,
SW87,
is
pressed,
the
slope
of
the
trigger
signal changes.
The
circuit
operates
as
follows
to
change
slope:
When
SW87
is
pressed,
the
positive
level
(with
respect
to
negative
levels in this circuit)
at
the
base
of
the
on
transistor
is
coupled
to
the
base
of
the
off
transistor.
This
raises
the
level
at
the
base
of
the
off
transistor
enough
to
bring
it
into
conduction and its
collector
goes negative.
The negative-going
change
at
the
collector
of
this
transistor
is
connected
to
the
base
of
the
on
transistor
to
turn
it
off.
The
multivibrator
switches
states
and
the
unit
is
triggered from
the
opposite
slope.
The
circuit
remains in
this
condition
until
the
CHANGE
SLOPE
button
is pressed
again
(or
changed
by
external
program).
The
trigger
slope
can
be
externally
programmed
through
terminal
27
of
the
front-panel PROGRAM
connector,
J30.
In
the
External
Mode
of
operation,
—
12.2
volts
is
applied
to
the
base
of
Q85
through
D89,
R89
and
R85
(see Operating
Mode
Power
for
explanation
of
how
External
Power
is
obtained).
Q85
is
reverse
biased
by
this
negative
voltage
at
its
base
and
positive-slope triggering
is
established.
Operation
of
the
remainder
of the
circuit
is
the
same
as
just
described
for
positive-slope
triggering
in
the
Manual
Mode.
To
change
the
trigger slope
to
minus,
grounding
external
program
slope
logic
is
connected
to
terminal
27
of
J30.
This
raises
the
level
at
the
base
of
Q85
positive to
forward
bias it. Q85
turns on
and
establishes
negative-slope
trig
gering.
Operation of
the
circuit
is
the
same
as
described
previously
for
negative-slope
triggering.
When
the
ground
ing
level
at
terminal
27
is
removed,
the
Slope
Multivibrator
reverts
to
positive-slope
triggering.
Trigger
Shaper
The
input
transistor,
Q104,
of
the
Trigger
Shaper
stage
is
a
low-impedance, current
driven
amplifier.
The
base
level
of
Q1
04
is set
at
about
—4
volts
by
divider
R101-
R102
between
—12.2
volts
and
ground.
This
establishes a
level
of about
—
3.5
volts
at
the
emitter.
The
input
signal
to
this
stage
is
applied
through
either
D66
or
D96
as
described
under
Slope
Comparator
and
Slope Multivibrator.
When
the
Slope
Multivibrator
raises
the
anode
level
of
either
diode
above
about
3
volts,
the corresponding
half
of
the
Slope
Comparator
is
connected
to
the Trigger Shaper
stage.
Tunnel
diodes
D1
05
and
D
115
are
connected
so
that
when
one
diode
is
in
its high-voltage
state
the other
diode
must
be in
its
low-voltage
state.
Therefore, when switched
by
the
trigger
signal,
either
D1
05
or
D
115 changes
to
its
high-
voltage
state
and
the
other
diode
changes
to
its
low-voltage
state.
Tunnel
diodes
characteristically
switch
from
the
low-
voltage
state
to
the
high-voltage state
very rapidly.
How
ever,
they
are
slower
when
switching
back
to
the
low-voltage
state.
The
configuration
used
in
this
stage
provides both a
fast leading edge
and
a
fast
trailing
edge on
the trigger
signal.
’
See
General
Electric “Tunnel Diode
Manual” for explanation of
tunnel
diode
operation.
Circuit operation
is
as
follows-.
Assume
that
the
signal
at
the
emitter
of
Q1
04
is
at its most
negative
level.
This
also
produces
a
negative level at
the
collector
of
Q1
04
which
holds
D
1
05
in its
low-voltage
state
and
D
115
in
its
high-
voltage
state. As
the
Slope Comparator
switches,
the
current
through
Q
104
increases.
This
increase
in
collector
current
switches
D
1
05
to
its
high-voltage
state
to
produce
a
fast
leading
edge
on
the
trigger
signal.
The
increase
in
current
through
Q
1
04
also depletes
enough
current
from
D1
15
to
switch
it
back
to
its
low-voltage
state.
L1
06
opposes
the
sudden
change
in
current
at
the
collector of
Q1
04
and
provides
a
higher
collector
load
during
the transition
period
to
aid
in
switching
the
tunnel
diodes.
The
circuit
remains
in
this
condition
until
the
Slope
Comparator
is
switched
again
by
the
trigger
signal applied
to
the input.
Then,
the
collector
current
of
Q1
04
decreases
and the
current through
D1
15
increases.
D
1
15
switches
to
its
high-voltage
state
to
produce
a
fast trailing
edge
on
the
trigger
signal. Current
through
D1
05
decreases
and
it
returns
to
its
low-voltage
state.
Again
L
1
06
aids
in
switching
the
tunnel
diodes.
The
trigger
signal
at
the
output
of
this
stage
is
connected
to
the Sweep
Generator
circuit
through
the
Pulse
Amplifier
and
to
the
Seek
Circuit
through
the
Seek
Circuit
Driver.
Pulse
Amplifier
The
trigger
signal
at
the
output
of
the
Trigger Shaper
stage
is
connected
to the
base
of
Q134 through
R131.
The *
3-10
Содержание 3B5
Страница 4: ...Fig 1 1 Type 3B5 Automatic Programmable Time Base unit Type 3B5...
Страница 15: ...Operating Instructions Type 3B5 TYPE 3B5 CONTROL SET UP CHART Fig 2 2 Control set up chart 2 7...
Страница 48: ...CO I o Fig 3 13 Delay and Timing Circuit logic block diagram Circuit Description Type 3B5...
Страница 61: ...GO i GO GO Fig 3 22 Seek Ciicuit Logic block diagram Circuit Description Type 3B5...
Страница 70: ...u k KJ Fig 3 29 Circuit conditions for Manual Mode operation Circuit Description Type 3B5...
Страница 71: ...w K w Fig 3 30 Circuit conditions for Seek Mode operation Circuit Description Type 3B5...
Страница 72: ...w I u U Fig 3 31 Circuit condition for External Mode operation Circuit Description Type 3B5...
Страница 88: ...Maintenance Type 3B5 Fig 4 9 Location of components on Logic Card 4 14...
Страница 89: ...u Oi Fig 4 10 Location of components on Counter Card Maintenance Type 3B5...
Страница 92: ...NOTES I...
Страница 104: ...NOTES...
Страница 106: ...Calibration Type 3B5 Fig 6 1 Recommended calibration equipment...
Страница 160: ......
Страница 176: ...J400 RtADOUT BOARD 3B5 PLUG IN A READOUT...
Страница 182: ...397 R E A D O U T B O A R D 10 6b READOUT BOARD...
Страница 184: ...FIG 1 FRONT SWITCHES TYPE 3B5 AUTOMATIC PROGRAMMABLE TIME BASE...
Страница 185: ...FIG 2 CHASSIS REAR 3 GS to TYPE 3B5 AUTOMATIC PROGRAMMABLE TIME BASE...
Страница 186: ...OPTIONAL ACCESSORIES...