I wish to have a design for a load cell using a strain gauge. Alternatively, if you can identify a commercially available product that satisfies the following requirements, I will pay the contracted payment amount for such an identification. It is not required that you build the load cell.
The overall configuration that is envisioned is a strain gauge mounted to a strip of aluminum (load element) with the following dimensions. The attached drawing shows an aluminum load element and a circuit board that measures a maximum of 20 mm x 20 mm. The circuit board will be positioned approximate 50 mm away from the load element.
Between 15 and 17 mm long (mean 16 mm)
Between 6 and 7 mm wide (mean 6.5 mm)
Between 1.4 and 1.6 mm thick (mean 1.5 mm)
The area available for the attachment of a strain gauge measures 5.5 mm x 13.0 mm.
The load cell will be used to measure stress on a rope.
The stress on the rope will range from 0 to 40 kg.
The supply voltage to the load cell will be 5.0 volts.
The output of the load cell should be a voltage that ranges from approximately 0 volts for no load to approximately 3.2 volts for full load.
The precision of the output voltage should be within +/- 5% of the stress at a fixed temperature.
Temperature compensation is not required.
Deliverables include:
Schematic of the circuit
Bill of materials for the circuit
It shall be possible to procure all materials from suppliers in the United States.
The recommended source for the strain gauge is http://www.omega.com/toc_asp/sectionSC.asp?section=E&book=pressure but other strain gauges will be considered.
Recommended sources for other components are www.digikey.com or www.mouser.com.
I am not experienced with load cell design, so feel free to ask questions if I have left anything out. Also feel free to make suggestions if the above description is found to be too limiting.