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2025-11-17 11:19 pm
Hey folks,
I’m building a little weight-measuring project with my Raspberry Pi, and I’m using the SEN-10245 load sensor to sense how heavy things are. The signal from this sensor is very small, so I’m planning to use an HX711 amplifier to read it properly and feed that into the Pi. This is similar to what others have done when building DIY scales.
Right now, I’ve wired the sensor up, powered everything, and I’m able to get readings, but they’re pretty noisy and drift a bit over time. I’ve read that temperature changes or how you mount the sensor can really affect stability.
I want to log weight data on the Pi and maybe trigger events (like send a notification) when a certain weight is reached. Before I go further, how would you calibrate the sensor? What amplifier would you use? How would you solve issues with drift or noise?
Thanks in advance for any help!
2025-11-20 11:15 pm
Hi @jordanm23,
I don't have experience with load sensors, but did you read
- https://www.adafruit.com/product/5974 with the short specs of the HX711 24-bit ADC I2C module, mentioning the use of a Wheatstone bridge configuration using 2 or 4 load sensors to compensate for temperature drift
- https://learn.adafruit.com/adafruit-hx711-24-bit-adc a guide how to use the HX711
- https://randomnerdtutorials.com/arduino-load-cell-hx711/ another practical guide, including a way to calibrate, but using only a single sensor
- https://www.allaboutcircuits.com/textbook/direct-current/chpt-9/strain-gauges/ description of and theory behind unbalanced, half- and full bridge configurations
- and Sparkufn's guides
https://learn.sparkfun.com/tutorials/getting-started-with-load-cells and
https://learn.sparkfun.com/tutorials/load-cell-amplifier-hx711-breakout-hookup-guide (including notes on calibration)
Load sensors are temperature sensitive, so you will have to compensate for that. One way is to use a temperature sensor near the single load sensor, but then you will have to do calibration measurements for your desired temperature range. Easier is to use 2 identical sensors in a half-bridge: one unloaded sensor that balances out the (same) temperature drift for the other loaded sensor. Or 4 sensors in a full bridge.
The HX711 amp/ADC with ith differential analog inputs is designed for a bridge setup.
For noise: use as less amplification as needed, and/or average several subsequent measurements.
Pingpong is fun