PROJECT: Determining weight with load cells.

In summary, the project involves using thin-film force sensors to measure the weight of a block placed on top of them, and displaying the total weight on a digital screen. The questions raised include whether a microprocessor is needed, if all circuitry can be put on a circuit board, and if the read out device can be reset to zero for a new load. Further research on weight measurement and strain gauges is recommended.
  • #1
RWS000
11
0
First, I am not an electrical engineer and am not to familiar with circuit boards.

PROJECT: I have a static load, represented by a block. The block has three very short legs (or feet 3/8" diameter each). The feet are located concentricly under the block. Under the feet I place three thin-film force sensors that will be in compression when loaded. The sensors need to be wired in (series? or Parellel?) to a digital read out screen.

GOAL: I would like to read on the digital screen the TOTAL weight of the block when it is set on a smooth, solid substrate and powered on.

QUESTIONS:
1) Is a microprocessor needed?
2) If so, for what?
3) Can all the needed circuitry (for the sensors and the digital screen info.) be put on a circuit board?
4) Can the digital read out device have a button to push that will re-set, or re-calibrate the device back to zero reading and then read the weight of a new load that has been added on top of the original block (without including the weight value of the original block)?
5) Can you explain what circuitry is needed?

I probably have missed a few things, so please fill in the blanks.

Thank you so much for your help...
RWS000
 
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  • #2
Aside from the electronics, here what the "big boys & girls" (METTLER TOLEDO) consider when designing a "www.toltec.co.nz/pdf/Weighmodule%20Hand%20book.pdf" . See if you can refine your questions after taking a peek. :smile:
 
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  • #3
Google has some good information.
Google "measure weight force sensor" or "measure weight strain gauge"
http://www.nerdkits.com/videos/weighscale/ has some good information.
 

1. How do load cells work?

Load cells work by converting a mechanical force into an electrical signal. When weight is applied to the load cell, it causes a change in the electrical resistance of the load cell. This change is then converted into a measurable output signal that can be used to determine weight.

2. What is the accuracy of load cells in determining weight?

The accuracy of load cells can vary depending on the type and quality of the load cell. Generally, load cells have an accuracy of around 0.1% to 0.5% of the measured weight. However, with proper calibration and maintenance, load cells can achieve even higher levels of accuracy.

3. How do you calibrate load cells for weight determination?

To calibrate load cells, a known weight is applied and the corresponding output signal is recorded. This process is repeated with different known weights to create a calibration curve. This curve is then used to determine the weight of objects based on the output signal of the load cell.

4. Can load cells be used for both static and dynamic weight measurements?

Yes, load cells can be used for both static and dynamic weight measurements. Static measurements are taken when the weight is at rest, while dynamic measurements are taken when the weight is in motion. Some load cells are specifically designed for dynamic weight measurements, while others can be used for both.

5. What are the common sources of error in weight determination using load cells?

The most common sources of error in weight determination using load cells include temperature fluctuations, vibrations, and improper calibration. It is important to properly maintain and regularly calibrate load cells to minimize these sources of error and ensure accurate weight measurements.

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