NF DM2571, User Manual

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DM2571 User Manual
30
F4 (Input R) key
to select input
resistance Background
Specify the input impedance to the
test leads (Input R). This specifies
the measurement terminal input
impedance, which is either Auto or
10 M
Ω.
The Auto mode selects high
impedance (Hi-Z) for the 100
mV, 1 V and 10 V ranges, and 10
M
Ω for the 100 V and 1000 V
ranges. In most situations, 10 MΩ is
high enough to not load most
circuits, but low enough to make
readings stable for high impedance
circuits. It also leads to readings with
less noise than the (Hi-Z) option,
which is included for situations
where the 10 M
Ω load is
significant.
Vs = ideal voltage of DUT
Rs = input impedance of DUT
Ri = input impedance of DM2571
(either 10M or 10G available (Hi-Z))
Deviation (%) = Rs/(Rs+Ri) * 100
Display
When “Auto” is selected, the display shows
an icon indicating the Auto mode is
currently being activated.