(A-B) C - Datron 1061A User Handbook Manual

Examples
of
measurement
using
(A-B)
and
f
C
To remove
the zero
offset
of a pressure transducer.
Most
pressure transducers have
a
standard
offset of
a
few
volts at 'zero' pressure. This
offset
may
be
removed from
subsequent
readings
by storing the
constant
in
store
'B'
and
placing the
instrument
into
'(A—
B)'
compute
mode.
To
compute
the current flowing
through
a
known
resistance.
Using
the
simple
formula
I
= V/R
the
value
of
I
may
be obtained
by measuring
the voltage
developed
across the
resistance.
The
value of R, say
lk
12
,
is
placed into store
'C and
the
instrument
used
in
the
4-
C
compute
mode. The
displayed
reading then
indicates the current
in
milliamps.
To
check a particular
component
is
within
its
stated
tolerance.
Suppose
we
have
a batch
of
39k
12
+
5
%
resistors
and
we
wish
to
know
each
resistor's
percentage
deviation
from
nominal.
The
equation
A—
x 100
N
gives the
percentage
deviation
from nominal,
requiring the entry of the
nominal
value into
both
B
and
C
stores.
Selecting
'(A—
B)'
and 4-
C
compute
modes
gives
a
direct
read-out
of
percentage
deviation.
6
%
-
4
%
'
%
DEVIATION
2%H
0
%
2
%
-
4
%
-
6
%
-
Nominal
To
measure
a resistance greater
than
20M12
By
connecting a
10M12
resistor in parallel
with
Rx
and
using the
'(A—
B)'
and '4-
C
compute modes
large resistances
can be measured and
displayed.
Hi
O
LoO
Rx
=
Ry Rz
Ry
-
Rz
Where Rz
=
Rx
in parallel
with Ry.
'
Measure Ry and
store
in
store
'B'.
Select '(A-B)'
and measure Rz
(display reads
Rz-
Ry).
Store
—
10
(Rz-Ry)
in store
'C',
using the
'Keyboard'
mode
and
select '-f-C.
The
display
now
reads
Rx
in
M12 (%
legend
displayed)
and
the accuracy of
the
reading
approximates to the
accuracy of
the
DVM
when
measuring
a
value equal to Rz. Use short screened
leads
to
reduce
any
errors
due
to noise.
3-10