which is fed through output terminals mounted on the front panel and this
current is used to drive the external indicator and at the same time to
provide negative feedback via a gain control mounted on the left side of the
front panel.
c. Input terminals on the front panel are coupled with a link to a
third terminal that connects the feedback circuit in either series or
parallel.
Learning Event 4:
DESCRIBE THE MODEL 9461A GALVANOMETER
1.
Functional description.
The Model 9461A as shown in Figure 2-12 is
termed a "Secondary" Galvanometer, as it is designed primarily for use with
a Model 9460A Nanovolt Amplifier. The cabinet is formica and has a hinged
top cover. Dimensions are 13 1/2 inches wide by 10 1/2 inches front to rear
by 7 1/4 inches high.
Weight is approximately 11 pounds.
The scale is
polarized to overcome the effects of ambient light and is backlighted so
that the entire scale may be easily observed.
2.
Specifications.
500mm/A or 0.002A/mm
Sensitivity:
(mm = millimeter)
Input resistance:
550 ohms
Display:
240mm zero center scale with 3/4-inch diameter
light spot, backlighted, polarized filter
Sensitivity ranges:
1/1, 1/10, 1/100, 1/1000 of full sensitivity
Period:
2.5 seconds
Terminals:
Input, low thermal copper
Ground terminal
Connectors:
Two-pin for lamp supply Model 9460A Nanovolt
Amplifier
Construction:
Formica-finished case
Dimensions:
13 1/2 in x 10 1/2 in x 7 1/4 in
(34 cm x by 27 cm x 18.5 cm)
Weight:
11 lbs
(4.5 kg)
Power:
120 volts ac/dc 12 watts
(includes power to Model 9460A lamp)
36
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