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tlfong01
tlfong01
3:28 AM
@MollyMal Ah, to measure something 4m x 1m large, you need to buy/customer make/DIY yourself a long sensor.
(1) BX120-3AA/BF1K-50AA High Precision Resistance Strain Gage Strain Gauge GAGE Full Bridge - Risym 价格 ¥3
https://detail.tmall.com/item.htm?spm=a220m.1000858.1000725.21.71a47174Xn9fyG&id=570651967500&skuId=4515647783810&areaId=810200&user_id=738263294&cat_id=2&is_b=1&rn=290157615a79390bacfc9c760ac9853a

(2) BX120-3AA to 100AA - ¥1.5 - ¥10
https://item.taobao.com/item.htm?spm=a230r.1.14.46.369d2ebesXK004&id=534262139452&ns=1&abbucket=9#detail
 
tlfong01
tlfong01
3:41 AM
@MollyMal Some TaoBao shops sells longer sensors but only up to 10cm. For even longer one, you need to customer make.
(3) BX120-3AA 应变计高精度电阻式应变片称重传感器BF1K-50AA电子称 天猫10年老店 Risym 价格 ¥3.03
https://detail.tmall.com/item.htm?spm=a220m.1000858.1000725.21.71a47174Xn9fyG&id=570651967500&skuId=4171611518427&areaId=810200&user_id=738263294&cat_id=2&is_b=1&rn=290157615a79390bacfc9c760ac9853a
 
tlfong01
tlfong01
4:25 AM
@MollyMal Actually I don't suggest you to start off with ESP8266/32, because the lerning curve is rather steep, the development time is long, comparing with using Arduino or Rpi. For Rpi, you can use free libraries.
How to run 2 load cells each with a HX711 on Rpi - Rpi SE 2020oct26hkt1222
https://raspberrypi.stackexchange.com/questions/117883/how-to-run-2-load-cells-each-with-a-hx711-on-rpi
@MollyMal I would also suggest you to create a blog or github, so that other weight sensor newbies can share your experience can share your experience. My old blog in rpi.org.forum that I showed you is out of dated, because it is for Rpi3B+, and a small weight sensor. I am also thinking of using longer 10cm sensors for a project on smart matress/bad, to monitor old people's sleeping disorder. I am Rpi4B Thonny Python. The following are examples of other uni, Cornell Uni group projects:
Cornell University ECE5725 Spring 2020 Rpi Group Projects
https://skovira.ece.cornell.edu/ece5725-spring-2020-projects/
 
 
1 hour later…
tlfong01
tlfong01
6:01 AM
@MollyMal You might have already noticed that my comments contains a lot of typo errors, because I am very slow in writing English, and this chat room does not allow me to edit old comments. My workaround is to copy and paste old comments in my personal reading and experiment log where I am edit and update freely any time. That is why I suggest you create your own blog or gitHub for your own project.
Now some updated info to my Penzu diary. Please feel free to copy and paste any thing to you own blog/github.
(1) Introduction to Strain Gauges - All About Circuits
https://www.allaboutcircuits.com/textbook/direct-current/chpt-9/strain-gauges/

(2) HX711 Python Library hx711 1.1.2.3 pip install hx711 - pypy.org
https://pypi.org/project/hx711/

(3) HX711 Python GitHub - gandalf15/HX711
https://github.com/gandalf15/HX711/
 

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