4-18
switch selects the conventional TVM mode of operation and the various full-scale null detector sensitivity
ranges when the instrument is operated in the differential mode of operation. The RANGE switch allows
selection of the desired input voltage range, positions the readout dial decimal point, and selects the
various ranges of the NULL SENSE switch. The readout dials provide a digital readout of the measured
voltage when the instrument is in the differential mode.
Figure 4-15.—Controls, terminals, and indicators.
MODES OF OPERATION
There are two primary modes of operation: the conventional transistorized voltmeter mode and the
differential null mode. These modes are described in the next paragraphs.
Conventional Transistorized Voltmeter (TVM) Mode
When the instrument is used as a conventional transistorized dc voltmeter, the circuitry is connected
as shown in figure 4-16. The null detector drives the front panel meter and provides a full-scale meter
deflection for any full-scale input. Positive or negative voltage measurements are made by reversing the
meter terminals through the contacts of the MODE switch.
