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SparkFun

5.0 (1 review)

$23.25 |
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5.0 (1 review)

The SparkFun Load Cell Amplifier is a small breakout board for the HX711 IC that allows you to easily read load cells to measure weight. By connecting the am...

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The SparkFun Load Cell Amplifier is a small breakout board for the HX711 IC that allows you to easily read load cells to measure weight. By connecting the amplifier to your microcontroller you will be able to read the changes in the resistance of the load cell, and with some calibration you’ll be able to get very accurate weight measurements. This can be handy for creating your own industrial scale, process control or simple presence detection.

This version of the SparkFun Load Cell Amplifier features a few changes that you specifically asked for! We have separated the analog and digital supply, as well as added a 3.3uH inductor and a 0.1uF filter capacitor for digital supply.

The HX711 uses a two-wire interface (Clock and Data) for communication. Any microcontroller’s GPIO pins should work, and numerous libraries have been written, making it easy to read data from the HX711. Check the hookup guide below for more information.

Load cells use a four-wire Wheatstone bridge configuration to connect to the HX711. 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 pin acts as an optional input that is not hooked up to the strain gauge but is utilized to ground and shield against outside EMI (electromagnetic interference). Please keep in mind that some load cells might have slight variations in color coding.

Note: Special thanks to Bodge for supplying the Library for the HX711!

Jargon buster

Plain-language definitions for the technical terms used above.

breakout
A breakout board carries a small or fine-pitched component and brings its connections out to standard, breadboard- and header-friendly pins. Describing a part as a breakout means it can be wired into a project without soldering directly to the component's tiny contacts.
electromagnetic interference
Electromagnetic interference (EMI) is unwanted electrical noise from nearby devices, cables, or radio signals that can disturb the signals carried in a wire or circuit. Shielding helps reduce this noise, which matters because cleaner signals make data and communication links less prone to errors and dropouts.
GND
GND is the ground or reference connection (0 V) for a circuit. When connecting two devices together, their grounds must be joined so both agree on what counts as a low or high signal.
GPIO
General-purpose input/output pins are microcontroller pins you can set in software to read signals, switch devices on and off, or connect to peripherals. The number of GPIO pins matters because it limits how many buttons, LEDs, sensors, and other parts you can wire directly to the board.
microcontroller
A microcontroller is a small computer on a single chip that runs a stored program and controls connected inputs and outputs such as buttons, sensors, displays and communication interfaces. In a device built around one, it is the part that executes the code and coordinates the device's behaviour.
Shield
An add-on board that plugs into a main controller board to give it extra features such as sensing, motor control or communication. Knowing a product supports shields helps you judge whether it can connect neatly into an existing maker-board setup.
Strain gauge
A strain gauge is a sensor element whose electrical resistance changes when it is stretched or compressed. It is commonly used to measure force, weight, pressure or bending, and because its resistance change is small it usually needs precise differential measurement electronics such as a high-resolution ADC.
VCC
VCC is the positive power-supply connection on a chip or module. Connecting it to the correct supply voltage is needed for the part to power on and helps avoid damaging the electronics.

SparkFun HX711 Load Cell Amplifier Schematic

Schematic · 58.6 KB · Click any page to view full size

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HX711 Datasheet

Datasheet · 263.2 KB · Click any page to view full size

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Supplier page — sparkfun.com

Supplier Description · 1.2 MB · Click any page to view full size

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Source Code

Open-source libraries, firmware & example projects for this product

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