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MODEL 615 ELECTROMETEX
SECTION
1.
GENERAL
DESCRIPTION
l-l.
GENERAL.
a.
The Keittlley
Model 615 Digital
Eleceromeeer
is a
fast,
accurate
and sensitive
Electrometer
with
digital
display.
It
is a versatile,
comp'letely
solid-state
instrument
which measures
a wide range of d-c voltage,
current,
resistance
and charge.
Thy4Electrometer's
input
resistance
of greater
than 10
ohms is the re-
sult
of extensive
instrument
development
with
high
in-
put impedance
transistors.
The Model 615 has all
the
capabilities
of conventional
VTVMs, but it
can also
make many more measurements
without
circuit
loading.
b.
The Electrometer
has four
decade voltage
ranges
from 0.100 volt
full
scale
to 100 volts,
12-decade
CUrrent
ranges
from 10-12 ampere full
scale
tcl 0.1 am-
pere,
11 decade
linear
resistance
ranges
from lo4 ohms
full
scale
to 1OL4 ohms, and seven decade charge
rang-
es from lo-11
coulomb
full
scale
to 1O-5 coulomb.
C.
The Model 615 employs
matched
insulated-gate
field-effect
~ransiseors
followed
by a transistor
dif-
ferential
amplifier
and complimentary
outpue
stage.
A large
amount of negative
feedback
is used for
sta-
biliey
and accuracy.
1-2.
FEATURES.
a.
Unique
input
circuit
provides
overload
profec-
tion
up eo 500 volts
on most ranges without
damage.
b.
Time stability
is better
than 1 millivolt/day
after
l-hour
warmup.
Less than 150 microvolts
per '=C
zero drift
with
temperature.
C.
Offset
current
less
than 5 x 1O-L5 amperes min-
imizes
zero offset
with
high
source
resistance.
d.
A front
panel
ZERO CHECK Switch
permits
check-
ing zero-offset
without
disturbing
the tneasurement
CiX"iC.
e.
Operarion
up to *lOO voles
above case ground
is
possible
without
affecting
the reading.
Isolatio"~
from csrcuit
low to case ground
is greaeec
than 106
ohms shunted
by 0.2 microfarad.
f.
Analog
output
provided
for
1 mA full
scale
re-
corders
such as the Keiehley
Model 370 Recorder
or
other
floating
instrument.
g.
Digital
display
enables
voltage'measurements
to
l O.Z% of reading
*I digit.
h.
Polarity
is automatically
indicated
on the dis-
Pk+,
i.
Display
rate
1s adjustable
from 24 readings
per
second to two readings
per minute
LO acconmadate
the
mode of data
retrieval.
j.
Analog-to-digital
converter
is a dual
slope
in-
tearaeing
type
circuit
to pro"ide
inaounity
to line
power frequency
pickup.
k.
Model 4401 Printer
Output.Cards
are available
for
factory
or user
installation.
This
option
pro-
vides
BCD outputs
far
significant
digits,
range,
pol-
arity,
sensitivity
and overrange.
Various
remaee
control
lines
are also
provided.
The Output
Buffer
cards
are easily
inserted
into
prewired,
premouneed
card-edge
connectors
an the Model 615 chassis.
04728
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