V/I OHMS MEASUREMENTS
(Model 487)
By using the V-Source in conjunction with its picoamme-
ter, the Model 487 can make resistance measurements
as high as 5.05 x 10i6fI. With V/I ohms selected, the re-
sistance is automatically calculated from the applied volt-
age and measured current (R=V/I) and displayed (in
ohms) on the Model 487.
The V/I ohms function is enabled by pressing SHIFT and
then OHMS.
To make VA ohms measurements:
1.
2.
3.
4.
5.
6.
7.
8.
With zero check enabled and the V-Source in
standby, connect the circuit shown in Figure 5.
Select a current range that gives the nearest full
scale reading or autorange, and perform zero cor-
rection by pressing SHIFT and then CORRECT.
Set the V-Source to OV on Ihe range that will be
used and press OPERATE to enable the source
output.
Press REL to cancel offset current.
Set the V-Source to the desired voltage level.
Disable zero check. The current measurement will
be displayed.
Enable V/I ohms by pressing SHIFT and then
OHMS.
To measure from a baseline resistance, enable ref
while in V/I ohms.
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