1. CONTROLS (cont.)
1.10 Generator Switch: The switch at the bottom center of the panel chooses
the generator to be connected, to the bridge* In the internal ac position
the output of the internal generator is connected to the bridge generator
corners. In the external generator position the bridge corners are
connected to the external generator terminals. In the internal dc
position the internal dc generator is connected to the bridge generator
corners
.
1.11 Galvanometer: The meter in the center of the panel is asensitive
gaiygLnometer which is used for indicating abridge balance. The two
mounting screws are connected to the galvanometer terminals so that
it may be easily connected to other external circuits. The large knob
on the galvanometer can be rotated for mechanically positioning the
galvanometer pointer. When the lock button is pushed in the direction
of the arrow, the galvanometer suspension is rigidly supported for
protection during transportation.
1.12 Power Switch and AC Amplifier Gain: The left-hand control knob on
the small upper panel controls the AC detector sensitivity. The power
switch for the unit is connected to the same knob. The adjacent pilot
light indicates when power is supplied to the bridge.
1.13 AC -DC Switch and AC Generator Gain; The right-hand control knob
on the small upper panel controls the ac generator output. In the
extreme counter-clockwise position, it switches the ac generator off
and the dc generator on.
1.14 DC Generator Voltage Switch: The switch on the right-hand side of
the small panel provides for high and low values of dc voltage^ for
resistance measurements. The low value gives greater sensitivity
for unknown resistors below about 100 ohms, and the high position
gives greater sensitivity above about 100 ohms* This switch has
no effect on the ac generator.
1.15 AC Generator Tuning Network: The upper right-hand plug-in unit
controls the frequency of the oscillator.
1.16 AC Detector Tuning Network: The upper left-hand plug-in unit
determines the frequency response of the detector. With this network,
the detector has anarrow acceptance band centered at the generator
frequency. With this network removed, the detector has aflat response.
1.17 AC Null Indicator: The electron- ray-tube visual null indicator provides
high sensitivity and rapid response. Anull is indicated by the maximum
opening of the eye
.
1.18 AC Amplifier Output Terminals: The two terminals at the top of the
small panel are for connecting an oscilloscope or other indicator to the
output of the detector amplifier. They are in parallel with the visual
null indicator. The black terminal on the left is connected to the bridge
chassis. The red terminal on the right is connected through acapacitoi
to the detector output.
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