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Figure 2. 1785A Input Transformer Connections
To configure the module for the slave mode, install a 2-pin female
connector onto J5, the 2-pin male header connector located
near the right edge of the module as shown in Figure 1.
Mute "Off " Mode of Operation
By not installing a jumper in either the priority (J4) or slave (J5)
position, the channel can not be muted, or cannot mute other
channels.
Phantom Power
To enable phantom powering of condenser microphones, install
a 2-pin female jumper onto J6, the 2-pin male header connector
located near J1 as shown in Figure 1. This will apply +36 VDC
to each side ("+" and "-") of the microphone's signal lines.
Figure 3. Block Diagram of the 1781A Input Module
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Figure 4. Remote Volume Control Applications
REMOTE VOLUME CONTROL CONFIGURATIONS
Remote Volume Control Connections
A remote volume control (RVC) may be used with the 1794
5-lug screw terminal connector assembly to vary the output level
of the input module. The resistance setting of a potentiometer
determines the amount of attenuation in the voltage -controlled
attenuator (VCA). Since only DC is present on the potentiometer
(no audio signal), the pot may be located long distances from
the mainframe. The RVC function is usable regardless of the
mute circuit's mode of operation.
To implement a remote volume control, connect an audio taper
potentiometer (10 kohm or greater) between pins 4 and 5 of the
1794 . Refer to Figure 4a.
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