HP Lab Series User Manual

4-52
The
-3
Volt
bias
source
provides
an
offset
CU?Tent
to
the
meter
circuit
which
compensates
for
the
programming cuITent
that
flows
through
the
cur-
rent
sampling
resistance.
Resistor
R38,
mounted on
stand-offs,
is
selected
so
that
the
offset
current
bucks
out
the
programming
current,
allowing
the
ammeter
to
be
zeroed.
4-53
ADDITIONAL
PROTECTION
FEATURES
4-54
The
supply
has
several
"special
purpose"
components
which
protect
the
supply
in
the
event
4-7
of
unusual
circumstances.
One
of
these
components
is
CR34
which
is
connected
across
the
output
ter-
minals
of
the
supply
and
prevents
internal
damage
from
reverse
voltage
that
might
be
applied
across
the
supply.
This
could
occur.
for example. during
Auto-Series
operation.
if
one
supply
were
turned
on
befcre
the
other.
4-55
Zener
diode,
VR3,
cannected
across
the·
series
regulator
·and
R54,
protects
Q6
from
the
effects
of
reverse
voltages.
•
•
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HP Lab Series Specifications

General

Brand	HP
Model	Lab Series
Category	Power Supply
Language	English