A digital weight sensor using an Arduino, bar load cell and HX711 24-bit ADC.

A bar load cell contains two strain gauge connected in a Wheatstone brigde. When a weight is on the load cell, the strain gauges change resistance. With excitation on the bridge, the change in resistance is proportional to voltage. This is read by a HX711 24-bit analog to digital converter for processing. The HX711 digitizes the voltage and sent to the Arduino serially.