1 GENERAL DESCRIPTION AND SPECIFICATIONS
The Model 10A70-2 is a general-purpose two-channel conditioner for use with DC-
excited load cells, pressure sensors, and any other conventional strain gage
transducer
employing a 4-arm bridge of nominal 350 Ω or higher, with a full-scale
range of 0.75, 1.50, or 3.00 mV/V.
The 10A70-2’s advanced design techniques overcome errors that traditionally plague
the strain-gage conditioning process. Separate excitation for each channel uses
remote sensing of bridge voltage and is slaved to a common System Reference Volt-
age. The result is consistently stable ratiometric measurement, unaffected by possi-
ble power-supply drift. Input impedances in excess of 10,000 MΩ are presented to
signal leads to eliminate cable resistance as a source of error. Allowable cable length
has virtually no practical limits.
ADDITIONAL 10A70-2 SPECIFICATIONS
Transducer Types
: Conventional 4-arm strain gage bridges, nominal 350 ohms (or
higher)
Input Ranges (Full-Scale): ±0.75, 1.50, or 3.00 mV/V; automatically selected—on an
individual channel basis—when the channel is configured; for System 10 channel
“type” codes assigned to 10A70-2 data channels, see Table 1, below. Since channel
zeroing is by digital techniques, no input balance control is provided. The allowable
input range, therefore, must include any
initial unbalance (which, in commercially
produced strain gage transducers, is usually negligible). Other transducers may
have to be externally trimmed to be used with the Model 10A70-2, if zero unbalance
exceeds 20% of full scale.
Excitation (per channel): Nominal 10 (i.e., ±5) V-DC; ±50 mA, maximum
Amplifier (per channel):
Common-Mode Range: ±1 V operating; ±9 V without instrument damage
Common-Mode Rejection Ratio: DC: -100 dB; at 60 Hz: -120 dB
Input Impedance: Differential: greater than 10,000 MΩ; Common-Mode: greater
than 10,000 MΩ
Offset: Initial: ±0.3 mV; vs. Temperature: ±0.05 µV/°C; vs. Time: ±5 µV/month
Gain Accuracy*: ±0.02% of full scale typical, following calibration
Gain Stability: vs. Temperature: ±50 ppm/°C; vs. Time: ±50 ppm/month
(cont’d)
* Initial (uncalibrated) inaccuracy may be as great as ±0.05% of full scale. Maximum error that
could occur upon replacement of a Model 10A70-2 not followed by calibration is ±0.1% of full
scale.
GENERAL DESCRIPTION AND SPECIFICATIONS 10A70-2.1
1.E.2.10A70-2
MODEL 10A70-2
DUAL STRAIN GAGE
CONDITIONER CARD
SYSTEM 10
ANALOG INPUT CARDS
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