Circuit
Description
—
Type
575
step
positions
of
the STEP
SELECTOR
switch).
However,
the
characteristics
of
the
external
load
must
be
such
that
the
voltage
drop
across
the
external
load
resistance
is
no
more
than
5
volts
when
the
current
through
it
is
2.4
amperes.
At
lower
currents,
however,
the
5-volt
figure
may be
exceeded.
The
simplified
diagrams
of
Fig.
3-13
and 3-14
show
the
operation
of
the
entire
Step
Amplifier
when
delivering
cur
rent
steps
to the
input
of
the
transistor
under
test.
Current
regulation
is
accomplished
by
maintaining
a
constant
voltage
drop
across
R246
for
each
step
of the
input
voltage
from
the
Step
Generator.
That
is,
each
time
the
input
voltage is
step
ped
15
volts,
the
voltage
drop
across
R246
should
change
1/30
of
15
volts,
or
0.5
volt,
and
remain
at
the new
voltage
for
the
duration
of
the
step.
This
will
provide
steps
of
con
stant
current
proportional
to
the
input
voltage
steps.
It
would
be
a
simple
matter
to
maintain
a
constant
voltage
across
R246,
proportional
to
the
input
steps,
if
the
voltage
at
the lower
end
of
R246,
(that
is,
the
voltage
at
the
input
to
the
resistor under
test)
were
constant.
In
other
words,
if
we
fix
the
voltage at
the
lower
end
of
R246
at
some
poten
tial,
say
ground,
the
voltage across
R246
would
remain
con
stant
for
the
duration
of
each
of
the
input
steps,
and
would
change
only
when
the
input
voltage steps
from
one
level
to
the
next.
However, the lower
end
of
R246
is
connected
to the
input
of
the
transistor
under
test
and
not
to
a
fixed
reference.
When
the
collector
sweep
voltage
is
applied
to
the
collector
of
the
transistor
the
voltage
at
the
input
of
the
transistor
will
change
and
the
voltage
at the
lower
end
of
R246
will change.
In
order
to
maintain
a
constant
voltage,
the
voltage
at
the
upper
end
of
R246
must
change
the
same amount and
in
the
same
direction
as
the
voltage
at
the
lower
end.
To accom
plish
this
action the
+1
Amplifier
and
the feedback loops
couple
any
voltage
change
at
the
lower
end
of
R246
to
the
difference
amplifier
V214-V224
which
in
turn,
through
the
cathode-follower
V233A
and
the
output
amplifier
V243- V253,
produces
the
same
voltage
change
at
the
top
of
R246.
Fig.
3-13
shows
the
circuit
configuration
when
the
POLARITY
switch
is
set
for a
negative
output.
The
operation
of
the
cir
cuit
will
be
explained
in
two
parts;
first,
to
show
how
the
voltage
at
the
top
of
R246
changes
in
proportion
to the
input
steps,
and
second,
to
show
how
the
voltage
at
the top
of
R246
changes
as
a
result
of
any
voltage
chanqe
at
the
bot
tom
of
R246.
Assume
the
input
voltage
changes
from
0
to
+15
volts
(1
step).
This
tends
to
make
the voltage at
the
grid
of
V214
go
in the
positive
direction,
and
the
plate
voltage
to
go
in
the
negative
direction.
The
voltage
at
both
the
grid
and
cathode
of
the
cathode-follower
V233A
goes
in
the
negative
direction,
following
the
plate
of
V214.
Q243
is
an
emitter
follower,
so
its
emitter
goes
in
the
negative
direction
carrying
with
it
the
base
of
Q253.
Since Q253 is also
connected
as
an
emitter-follower,
for
negative-polarity
operation,
its
emitter
and
hence
the
voltage
at
the
top
of
R246
goes
in
the
nega
tive direction.
A
positive
step
at the
input
will therefore
produce
a
nega
tive
step
at
the
top
of
R246.
This
negative
step
also
appears
at
the
lower
end
of
R203,
since
this
point
is
connected
to
the
top
of
R246.
This
means
that
as
the top
of
R202
goes
positive
the
lower
end
of
R203
goes
negative.
The
amplifier and
feedback
network
therefore
acts
as
a
“
teeter-totter"
circuit
that
pivots
about
the
junction
of
R202-R203;
the
grid
of
V214
is
at
virtual
ground,
or
zero,
potential.
Since
the
top of
R203 is
at
ground
potential,
the
change in
voltage
across
R246,
due
to
an
input
step,
is equal
to
the
change
in
voltage
across
R203.
R202 and R203
make
up
a
Fig.
3-13. Simplified
diagram
of
the Step Amplifier
for negative-going
current steps.
3-9
Содержание 175
Страница 4: ...VWTICM OINltAlO TRANSISTOR CUM TRACfR UB l COUlClO r hokizoniai VCKIJ O lUnK Hix M Type 575 z ...
Страница 6: ...NOTES ...
Страница 26: ...NOTES ...
Страница 48: ...NOTES ...
Страница 54: ...Recalibration Type 575 C706 Fig 5 3 Left Side View 5 6 ...
Страница 56: ...NOTES ...
Страница 61: ...O I Ui Fig 6 6 Simplified circuit diagram of Type 175 Transistor Curve Tracer High Current A dapter ...
Страница 100: ...INPUT AMPLIF1E ...
Страница 104: ...TYPE 575 TRANSISTOR CURVE TRACER ...
Страница 108: ...OSCILLATOR 4OOV UNREG TYPE 575 TRAN5I5TOR CURVE TRACER AB ...
Страница 114: ...234 VAC 117 VAC PRIMARY CONNECTIONS FOR 234VOLT OPERATION ___I TYPE 175 TRANSISTOR CURVE TRACER HIGH CURRENT ADAPTOR ...
Страница 115: ... 300 ...
Страница 117: ...TYPE 175 TENT S N 393 PARTS LIST CORRECTION CHANGE TO SW510 TRANSISTOR SELECTOR 260 636 M6983 664 ...
Страница 119: ...Type 175 Tent S N 570 PARTS LIST CORRECTION Change to Q233 151 0137 00 2N21U8 MIO 298 1165 ...
Страница 123: ...INSTRUCTIONS cont uu y uj r uu y P 2AO MJ i DfeZOC 4K cx zdd uu gn UJ bK uj bn T JU O Page 4 of 4 040 0223 00 ...
