Load Cell- Detailed Instructions

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(1 hr) Prepare detailed instructions showing how the part works and what it can do.

• Weight Limits
• Accuracy and Precision compared to commercial kitchen scale

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20 kg weight limit

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Part must be calibrated with a known weight first. https://www.adafruit.com/product/4543#technical-details

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Reading with 100g weight

[mlivai]

Prepare more detail about the HX711

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The load cell has a 20 kg weight limit (5). Internally, the load cell contains a Wheatstone bridge, with a variable resistance that can be measured with an ADC, like the HX711 (5). Before the load cell can be use to measure weight, it must first be calibrated (5). The load cell is first zeroed, with the reading from the HX711 saved. Then, a known weight must be placed on the HX711, with the reading from the HX711 saved. Now, when the HX711 reads an unknown weight, first, the difference between the unknown and zero HX711 values are found. Then, this difference is divided by the HX711 value for the test weight. Finally, that quotient is multiplied by the test weight in grams, returning the unknown weight in grams. This process can be seen in Figure 7. The HX711 used on the breakout board is an ADC with 24 bits of precision (5).