Model 3770
DC STRAIN GAGE PANEL METER
Tech Tip on use of wide range settings for the DC Strain Gage Conditioner
Due to multiple amplifier stages within the 3770 instrument, attention to the proper gain setting and understanding of
the sensor inputs should be reviewed to produce a linear- amplified analog output signal and display reading.
The wide span – gain control (as shown in the front panel diagram) has 16 positions to amplify the incoming signal by
incremental steps. Each step is positioned so the Coarse and Fine Span potentiometer controls overlap each step to
provide a continuous linear gain of the signal from 0.5 mV/V to 10.00 mV/V full scale. Below is a table of each wide
gain steps, indicating the nominal low and high input signal range per position – full scale in mV/V to the meter.
Note: When using 5 V excitation, increase the table values by a factor of 2.
Wide Span
Position
SPAN-Low
mV / V
SPAN-High
mV / V
0
3.90
5.80
1
3.30
4.90
2
2.90
4.20
3
2.50
3.60
4
2.10
3.10
5
1.80
2.70
6
1.50
2.30
7
1.30
1.90
8
1.10
1.70
9
1.00
1.40
A
0.84
1.20
B
0.72
1.00
C
0.62
0.92
D
0.53
0.80
E
0.45
0.65
F
0.38
0.58
DC Strain Gage Sensors sensor:
DC Strain Gage Sensors will typically specify their electrical sensitivity in mV/V for traditional foil gage transducers
or in mV full scale for semiconductor type sensors; either type will function with the 3770 unit as dictated by the
excitation voltage needed along with the full scale output of the sensor. The 3770 has selectable excitation of 5 and
10 Vdc and a maximum specified input of 50.0 mV (with 20% over-range) into the meter. As a reference, the above
table can be used as a guide to determine the working full scale range of the transducer during calibration and the
proper position of the Wide Span control. Note that additional gain or less gain can be accomplished as needed if an
expanded or reduced area of the sensor measurement level is required.
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