Measurement circuit for load cell mass comparator
AssigneesFrazier Precision Instrument Company, Inc., Holometrics, Inc.
InventorHoward P. Layer
Life of this patent
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Abstract
The strain gauge bridge circuit located in the load cell of a load cell mass comparator is modified to provide temperature stability by coupling a remotely located temperature compensating circuit between the two normally connected output ends of strain gauges in adjacent arms of the bridge. The compensating circuit is comprised of a pair of series connected low noise, drift free precision resistors of relatively low resistance value compared to the resistance of the strain gauges. The precision resistors are shunted by relatively high valued potentiometers which operate to balance the bridge. One potentiometer additionally includes a series connected high value precision resistor for providing fine balance while the other potentiometer is used for coarse balance.
Claims12
A temperature compensated load sensing circuit for a load cell mass comparator including a load cell containing a plurality of strain gauges connected to form arms of a bridge circuit connected to a measuring circuit, comprising the combination of:
- a pair of series connected resistance means coupled between the output side of the strain gauges in a first of two adjacent arms of said bridge circuit, said resistance means being of a relatively low resistance value compared to the resistance value of said strain gauges;
- potentiometer means shunted across at least one of said pair of series connected resistance means, said potentiometer means having a relatively large resistance value compared to the resistance value of said resistance means and further including an adjustable voltage output terminal;
- and
- means connecting said output terminal of said potentiometer means and the output side of the strain gauges in the second of two adjacent arms of said bridge circuit to said measuring circuit.
Dependencies are inferred from the claim text.