The single-channel Model 4077 is a versatile general-purpose instrument for input of pressure, force, torque, weight, and other variables measured by DC-excited strain gage transducers.
Unlike the other 4000 Series "Standard Input Models," the 4077 provides two special analog channels for real-time capture of both positive and negative peak input values. (ALL 4000 instruments are capable of digital peak capture, via special "MAX" and "MIN" data channels. The validity of digitally captured peak values is necessarily limited, however, by the scan rate of the instrument's Central Processor. This is not the case with the 4077's purely analog peak-capture capability, which yields true real-time maxima and minima, regardless of the current scan rate.)
The 4077 accepts a single input from any DC-excited load cell, pressure sensor, or other conventional 4-arm strain gage bridge, nominal 120 Ω or higher, with a full-scale range of 1.5 or 3.0 mV/V. Advanced circuit design overcomes many of the errors traditionally afflicting the strain gage measurement process, resulting in rock-solid digital indication and noise-free analog output.
Other important 4077 features include
- Selectable bridge excitation (nominal 5 or 10 VDC)
- Remote sensing and regulation of bridge excitation—eliminates errors from temperature effects on cable resistance and yields consistently stable ratiometric measurement, unaffected by possible power-supply drift
- Input impedance in excess of 100 megohms preserves the validity of factory calibration, prevents conversion of common-mode to normal-mode signals, and eliminates remaining errors attributable to cable resistance. Allowable cable length has virtually no practical limits.
