Table of Contents
Advertisement
CIRCUIT
DESCRIPTION
MODELS 610B,
6LOBR ELECTROMETERS
.I101
?
L
Amplifier
+250 v z
Rs
(
.
I
FAST
-265 v C
Floating
Gnd
I
FIGURE 15.
Block
Diagram
of Model
610B as a Picoanuneter.
Circuit
designations
refer
to schematic
diagram.
SlO6 is
the tiltiplier
Switch;
I&, is
the
resistor
for
a given
setting.
Rs is
the
resistor
selected
by the Range Switch,
SlOl.
5102 is
the FEEDBACK Switch.
Ground
references
correspond
to schematic.
3-4.
AMMEIER OPERATION.
a.
Normal
Methc.4.
In the normal
method
of current
measurements
(FEEDBACK
Switch
in NORMAL position),
one of
the
Range Switch
resistors,
R102 through
Rl12,
shunts
the
input.
(See Figure
15.)
The Modal
6lOB than
measures
the
voltage
drop
acros8
the
resistor.
The meter
is
calibrated
to read
the
current
in amperes
for
the
appropriate
range.
b.
East
Method.
In the
fast
method
0f current
measurements
(FEEDBACK Stitch
in FAST position),
the
Model
610B functions
as an
anmeter
with
negative
feedback.
The differential
amplifier
output
is
divided
by the tiltiplier
Switch
resistors,
R156 to R166,
and fed back
to the amplifier
input
through
a feedback
resistor
selected'with
the Range Switch.
(See Figure
15.)
Floating
ground
is
connected
to the
low impedance
side
of the
input,
and the
output
ground
is
floating.
This
method
increases
the
response
speed by minimizing
the
effects
of input
capacity;
it
also
reduces
the
input
drop
to less
than
1 millivolt.
3-5.
OHhMEX'ER OPERATION.
a.
NoMl
Method
In the normal
method
of resistance
measurements
(FEEDBACK
Switch
in NORMALposition),
the Model
610B uses
a constant-current,
voltage-drop
circuit.
Refer
to Figure
16.
&
is
the unknown
resistor.
A voltage
source,
E,
applies
a potential
acros8
&.
The source
is
obtained
from
the
+21 volt
supply
through
the
resistor
divider
network,
Rll4
through
Rll8.
E varies
from 0.1
to
10 volts,
depending
upon
the
OHMS range
used.
The voltage
source
is
connected
between
floating
ground
and the
input
grid
of V103 through
R,,
the
range
re-
sistor.
Rs is
one of the
resistors,
R102 through
R112.
Since
feedback
to the
24
1064R
Advertisement
Table of Contents
