INSTRUCTION
MANUAL
-
MODEL DLP 400-5-75OA
—
23
5.8
PULSE
This
mode
converts
the
Dynaload
into
a pulse
load,
which
may
be
varied
in
amplitude
and
frequency as
well
as
superimposed upon
a
fixed
DC
load.
The
pulse
is
generated
by
a
CA3140E operational
amplifier.
The
frequency
is
controlled
by
R126B,
which
controls
the
charging
rate
of
C5. The
amplitude
of
the
pulse
is
controlled by
R126A.
The
output
of
the
square
wave
generator
is
fed
to
the
non-inverting
input
of
U1
along
with
the
5A
constant
current
circuit.
The
inverting
input
is
connected
to
the
top
(+)
of
SH101.
As
the
non-inverting
input
is
driven
positive
by
the
square
wave
generator,
the
output of U1 rises,
driving
the
power circuit. The
current
then
rises
until the
voltage
across
the
shunt
is
sufficient
to raise
the
voltage
at
the
inverting
input,
turning U1
off.
If
a portion
of
the
voltage
on
the
non-inverting
input
of U1
is
constant,
as
selected
by
the DC
load
adjust
controls,
the
input
current
will
be maintained
at
the
fixed
level
selected,
and
rise as
the
square
wave
generator
drives
the
non-ivnerting
input
more
positive, thus
giving a
pulse
load
superimposed
upon
a
fixed DC
load.
If
the
pulse
load is
desired
to return ot no-load, the
DC
load
adjust pots
should be
turned
fully
counterclockwise.
A
sync
output
pulse
is
taken
from
an
amplifier
driven
directly from the output of
the
square
wave
generator,
creating
a
pulse
which
coincides with the leading
edge
of
the
load
pulse
and
may
be
used
to
trigger
additional
test
equipment
.
[ELE400-5-75QA]
