Weight sensor 0 - 20Kg + HX711 load cell amplifier

Force / load sensor to measure weight from 0 to 20 Kg - Load cell and HX711 cell amplifier

The "Load Cell Amplifier" is a small board with the HX711 IC used to read the cells load and measure weight. By connecting the amplifier on a microcontroller, it is possible to read the resistance of the load cell. Notice that a calibration process is required to be able to make very accurate weight measurements.

Load Cell + Amplifier is very handy to create your own scale, process control or simple presence detection.

The HX711 uses a two-wire interface (Clock and Data) for communication compatible with any microcontroler. Many libraries have been written and available on Internet which make it easy to read data from the HX711.

Load cells use a four-wire Wheatstone H-Bridge (Wikipedia, english version) configuration connected to the HX711 amplifier. These are commonly colored RED, BLK, WHT, GRN and YLW. Each color corresponds to the conventional color coding of load cells:

• Red (Excitation+ or VCC)
• Black (Excitation- or GND)
• White (Amplifier+, Signal+ or Output+)
• Green (A-, S- or O-)
• Yellow (Shield)

The YLW is ususally not used even if connected to the gauge. Connect it to the ground would protect the Wheatstone H-Bridge against electromagnetic interference (EMI protection).
Please keep in mind that some load cells might have slight variations in color coding.

Technical details

• Load Cell Size: 80mm x 13mm x 13mm
• Load Cell range: 20 Kg
• HX711 datasheet (pdf)
• Arduino library (GitHub, Sparkfun)