Hi, I followed this tutorial: https://www.youtube.com/watch?v=LIuf2egMioA and his Git repo: GitHub - olkal/HX711_ADC: Arduino library for the HX711 24-bit ADC for weight scales . Looks like popular one, so I guess proposed wiring & code are right. I used the Half bridge configuration - 2 load cells…

I meant something like: [image] Take a wire and connect it to GND and the other end to E-, or to the E- end of your bridge. I would predict that the voltage at E- would move down to 0V, and from A+/A- to ground would move to 2.5V, and the millivolts between A+/A- would be near zero and also chan…

[image] DaveX: Sometimes the colors are wrong on the load cells. Disconnect the load cells completely and check that the resistance from black-to-while is 2000 ohms, and from black to red =1000 ohms, and white to-red=1000 ohms on each of them. Red should the middle of the half-bridge. If not, wh…

OK, the only thing I can think of is that the E- on the HX711 board isn't good. If you wire just one load cell's white/black to E+/E-, E+ should be 5V and E- should be zero, with the red wire at 5V*1000/(1000+1000)= 2.5V If E- comes up to 5V, it is a bad E- on the HX711.

[image] DaveX: If your A+/A- input voltage is bigger than 20mv When bridge connected or not? When connected they're V_in, when disconnected it's 0.3v

E+ and E- were 5V. The red was also 5V. Point is I tried already 3 different HX711 (though all purchased from same shop).

When connected and operating, the bridge should be balanced enough to deliver a +/-20mV signal into A+/A-, If it does more, then the +/-20mV times the Gain hits the 0V/5Vrails at +/-0.020*128=+/-2.5V Since when connected, everything is a 5V, then a 0.0000V difference between A+/A- is delivering a…

Some HX711 boards have a production defect: [image] Load cell amplifier HX711 - wrong ground? Sensors Hi I have this type hx711 card I have read that ground is not properly connected to pin 5 on chip. Se yellow line for possible modification Can anybody confirm this? …

DaveX beat me to it, but here is another reference to that same production fault: https://forum.arduino.cc/t/hx711-mh-boards-with-potential-pcb-error/411774

[image] mikethe1: if I calibrate with 200 (the Git repo works unitless, so in that case grams), I get constantly random numbers in the range of [-100,300] no matter what load I apply Let me get this correct. You can successfully make a calibration but when you go back to make an actual measu…

No, after calibration, no mater what load I place (including 0), the results is simply fluctuations (noise) around the calibration value...

The bad HX711's ~0V difference on A+/A- is giving you a Garbage-In-Garbage-Out calibration.

2 load cells (half wheatstone bridge) + HX711 + ESP32: Works, but faulty measurements

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DaveX February 8, 2024, 2:35pm 14

Some HX711 boards have a production defect:

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2 load cells (half wheatstone bridge) + HX711 + ESP32: Works, but faulty measurements

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