• Weight Sensor Kit 1KG - Load Cell Amplifier HX711 is a device designed to measure weight with high precision. It consists of two main components: a 1kg load cell and an ADC amplifier module HX711. The load cell is a transducer that converts force into an electrical signal. In this case, it is designed to measure up to 1kg of weight. The electrical signal varies in response to the applied force and can be used to calculate the weight of the object being measured.
• The ADC amplifier module HX711 is equipped with a high-precision 24-bit analog-to-digital converter chip that can accurately measure the electrical signal from the load cell. It has two analog input channels and a programmable gain amplifier with a maximum gain of 128. This allows for greater flexibility in adjusting the sensitivity of the measurement. The input circuit of the ADC amplifier module can be configured to provide an electrical bridge voltage, which is particularly useful for measuring pressure and weight. This makes it an ideal choice for projects that require accurate weight measurements, such as in kitchen scales, luggage scales, and other similar applications.

Features:

• Weight Sensor:
  • High-precision: The kit uses a 1kg load cell and a high-precision 24-bit ADC amplifier module to provide accurate weight measurements.
  • Adjustable gain: The amplifier module has a programmable gain amplifier with a maximum gain of 128, allowing for greater sensitivity in weight measurements.
  • Two analog input channels: The amplifier module has two analog input channels, providing greater flexibility in measurement applications.
  • Bridge voltage input: The input circuit of the amplifier module can be configured to provide an electrical bridge voltage, which is particularly useful for measuring pressure and weight.
• HX711 Module:
  • Internal 24bit ADC amplifier
  • Two selectable differential input channels
  • On-chip active low noise PGA with selectable gain of 32, 64 and 128
  • On-chip power supply regulator for load-cell and ADC analog power supply
  • Output sensing range depends on the input voltage
  • The higher the pressure force, the higher the output analog voltage.
  • Simple digital control and serial interface: pin-driven controls, no programming needed for ease of usage.
  • Simultaneous 50 and 60Hz supply rejection for better accuracy.
  • Has an oscillator onboard eliminating external components.
  • Has optional external oscillator

Specification:

• Weight Sensor:
  • Rated Load: 1Kg
  • Rated Output: 1.0 mV/V ± 0.15 mV/V
  • Zero Output: ± 0.1 mV/V
  • Creep: 0.03% F.S ./30 min
  • Input End: Red + (power), Black - (power)
  • Output End: Green + (signal), White - (signal)
  • Recommended operating voltage: 3 ~ 12 VDC
  • Maximum operating voltage: 15 VDC
  • Input Impedance: 1115 ± 10% Ω
  • Output Impedance: 1000 ± 10% Ω
• HX711 Module
  • Operation Voltage: 2.7 - 5 V
  • Operation Current: < 1.5 mA
  • Sample rate: 10 Hz
  • Dimension: 16 x 24 Mm
  • Differential input channels: 2

Applications:

• Kitchen scales: The kit can be used to create a precise weighing scale for cooking or baking applications.
• Luggage scales: The kit can be used to create a portable luggage scale to measure the weight of bags and suitcases.
• Industrial weighing: The kit can be integrated into industrial equipment to measure the weight of various products or materials.
• Agriculture: The kit can be used to measure the weight of livestock, feed, and other agricultural products.
• Robotics: The kit can be used to create a robotic arm or gripper that can lift and weigh objects with high precision.
• Medical equipment: The kit can be used to create medical devices that require precise weight measurements, such as infant scales or hospital bed weight sensors.
• Fitness equipment: The kit can be used to create fitness equipment that tracks weightlifting progress or measures body weight.
• Logistics and shipping: The kit can be used to create a system that measures the weight of packages and determines shipping costs.

Pin Connections:

• Weight Sensor:

• HX711 Module:

Package Includes:

• 1 x HX711 Module
• 1 x Load Cell 1Kg

Sample Project:

Circuit:

Library:

• The HX711 library is available here: https://github.com/bogde/HX711
• See this link on the Arduino website for instructions on how to add the library to your Arduino IDE: https://www.arduino.cc/en/Guide/Libraries

Code:

• The first software step is to determine calibration factors for the scale. To do this, run this code:

/*
 Example using the SparkFun HX711 breakout board with a scale

 This is the calibration sketch. Use it to determine the calibration_factor that the main example uses. It also
 outputs the zero_factor useful for projects that have a permanent mass on the scale in between power cycles.

 Setup your scale and start the sketch WITHOUT a weight on the scale
 Once readings are displayed place the weight on the scale
 Press +/- or a/z to adjust the calibration_factor until the output readings match the known weight
 Use this calibration_factor on the example sketch

 This example assumes pounds (lbs). If you prefer kilograms, change the Serial.print(" lbs"); line to kg. The
 calibration factor will be significantly different but it will be linearly related to lbs (1 lbs = 0.453592 kg).

 Your calibration factor may be very positive or very negative. It all depends on the setup of your scale system
 and the direction the sensors deflect from zero state
 This example code uses bogde's excellent library:"https://github.com/bogde/HX711"
 bogde's library is released under a GNU GENERAL PUBLIC LICENSE
 Arduino pin 2 -> HX711 CLK
 3 -> DOUT
 5V -> VCC
 GND -> GND

 Most any pin on the Arduino Uno will be compatible with DOUT/CLK.

 The HX711 board can be powered from 2.7V to 5V so the Arduino 5V power should be fine.

*/

#include "HX711.h"

#define LOADCELL_DOUT_PIN  3
#define LOADCELL_SCK_PIN  2

HX711 scale;

float calibration_factor = -7050; //-7050 worked for my 440lb max scale setup

void setup()
{
    Serial.begin(9600);
    Serial.println("HX711 calibration sketch");
    Serial.println("Remove all weight from scale");
    Serial.println("After readings begin, place known weight on scale");
    Serial.println("Press + or a to increase calibration factor");
    Serial.println("Press - or z to decrease calibration factor");

    scale.begin(LOADCELL_DOUT_PIN, LOADCELL_SCK_PIN);
    scale.set_scale();
    scale.tare(); //Reset the scale to 0

    long zero_factor = scale.read_average(); //Get a baseline reading
    Serial.print("Zero factor: "); //This can be used to remove the need to tare the scale. Useful in permanent scale projects.
    Serial.println(zero_factor);
}

void loop()
{

    scale.set_scale(calibration_factor); //Adjust to this calibration factor
    Serial.print("Reading: ");
    Serial.print(scale.get_units(), 1);
    Serial.print(" lbs"); //Change this to kg and re-adjust the calibration factor if you follow SI units like a sane person
    Serial.print(" calibration_factor: ");
    Serial.print(calibration_factor);
    Serial.println();

    if(Serial.available())

    {
        char temp = Serial.read();
        if(temp == '+' || temp == 'a')
        calibration_factor += 10;
        else if(temp == '-' || temp == 'z')
        calibration_factor -= 10;
    }
}

• After calibrating the scale, you can run this sample program, then hack it up for your own purposes:

/*
 Example using the SparkFun HX711 breakout board with a scale

 This example demonstrates basic scale output. See the calibration sketch to get the calibration_factor for your
 specific load cell setup.

 This example code uses bogde's excellent library:"https://github.com/bogde/HX711"
 bogde's library is released under a GNU GENERAL PUBLIC LICENSE

 The HX711 does one thing well: read load cells. The breakout board is compatible with any wheat-stone bridge
 based load cell which should allow a user to measure everything from a few grams to tens of tons.
 Arduino pin 2 -> HX711 CLK
 3 -> DAT
 5V -> VCC
 GND -> GND

 The HX711 board can be powered from 2.7V to 5V so the Arduino 5V power should be fine.

*/

#include "HX711.h"

#define calibration_factor -7050.0 //This value is obtained using the SparkFun_HX711_Calibration sketch

#define LOADCELL_DOUT_PIN  3
#define LOADCELL_SCK_PIN  2

HX711 scale;

void setup()
{
    Serial.begin(9600);
    Serial.println("HX711 scale demo");

    scale.begin(LOADCELL_DOUT_PIN, LOADCELL_SCK_PIN);
    scale.set_scale(calibration_factor); //This value is obtained by using the SparkFun_HX711_Calibration sketch
    scale.tare(); //Assuming there is no weight on the scale at start up, reset the scale to 0

    Serial.println("Readings:");
}

void loop()
{
    Serial.print("Reading: ");
    Serial.print(scale.get_units(), 1); //scale.get_units() returns a float
    Serial.print(" lbs"); //You can change this to kg but you'll need to refactor the calibration_factor
    Serial.println();
}

References:

• https://www.sgbotic.com/products/datasheets/sensors/hx711_english.pdf
• https://github.com/dcrystalj/hx711py3
• https://en.wikipedia.org/wiki/Wheatstone_bridge
• https://www.instructables.com/How-to-Interface-HX711-Balance-Module-With-Load-Ce/
• https://www.youtube.com/embed/-834OB4U_30?feature=oembed&autoplay=1