ESP8266 NodeMCU with Load Cell and HX711 Amplifier (Digital Scale)
Scale) In this project, you'll learn how to use a load cell and the HX711 amplifier to make a scale with the ESP8266 NodeMCU. First, you'll learn how to connect the scale's load cell, HX7…
Know the mission before touching a wire.
Understand what you are making, prepare the right tools, and make the workbench safe.
Project details
ESP8266 NodeMCU with Load Cell and HX711 Amplifier (Digital Scale) is a iot project. Scale) In this project, you'll learn how to use a load cell and the HX711 amplifier to make a scale with the ESP8266 NodeMCU. First, you'll learn how to connect the scale's load cell, HX7…
- Source pages
- 950-954
- Named parts
- 5
- Build goal
- Working, tested prototype
Tools you need
- Digital multimeter
- Wire stripper and side cutters
- Soldering iron with a fine tip
- Current-limited bench supply
- Computer with a data-capable USB cable
Use eye protection, good lighting, and a clean insulated surface throughout the build.
Safety precautions
- Disconnect every power source before changing a connection.
- Check component polarity, pinout, and supply voltage twice.
- Use a current limit for the first power-up.
- Keep liquids, loose metal, and uninsulated wires away from the bench.
Gather, identify, and understand every part.
Use the standardized inventory, then open What's this? to learn each part's role, advantages, limitations, handling, and specifications.
What's this?Image, role, pros, cons, handling & specifications
ESP8266
A programmable controller that reads inputs, makes decisions, and drives the project's outputs.
What it does hereIt is the control centre and must use the documented board, pin map, supply, and logic level.
Buy / compare this part ↗Advantages
- Reprogrammable and reusable
- Large learning ecosystem
- Complex behaviour remains changeable
Limitations
- GPIO voltage and current are limited
- Some pins affect boot or communication
- Loads normally need a driver
Handling
- Disconnect power before rewiring
- Avoid static discharge
- Never power motors, relays, or pumps directly from GPIO
Specifications to verify
- Use the exact model, value, package, and rating listed for ESP8266; similar-looking parts are not always interchangeable.
- Confirm operating voltage, logic level, pinout, memory, USB interface, and maximum GPIO current.
What's this?Image, role, pros, cons, handling & specifications
ESP32
A programmable controller that reads inputs, makes decisions, and drives the project's outputs.
What it does hereIt is the control centre and must use the documented board, pin map, supply, and logic level.
Buy / compare this part ↗Advantages
- Reprogrammable and reusable
- Large learning ecosystem
- Complex behaviour remains changeable
Limitations
- GPIO voltage and current are limited
- Some pins affect boot or communication
- Loads normally need a driver
Handling
- Disconnect power before rewiring
- Avoid static discharge
- Never power motors, relays, or pumps directly from GPIO
Specifications to verify
- Use the exact model, value, package, and rating listed for ESP32; similar-looking parts are not always interchangeable.
- Confirm operating voltage, logic level, pinout, memory, USB interface, and maximum GPIO current.
What's this?Image, role, pros, cons, handling & specifications
MODULE LEARNING VIEWNodeMCU
A programmable controller that reads inputs, makes decisions, and drives the project's outputs.
What it does hereIt is the control centre and must use the documented board, pin map, supply, and logic level.
Buy / compare this part ↗Advantages
- Reprogrammable and reusable
- Large learning ecosystem
- Complex behaviour remains changeable
Limitations
- GPIO voltage and current are limited
- Some pins affect boot or communication
- Loads normally need a driver
Handling
- Disconnect power before rewiring
- Avoid static discharge
- Never power motors, relays, or pumps directly from GPIO
Specifications to verify
- Use the exact model, value, package, and rating listed for NodeMCU; similar-looking parts are not always interchangeable.
- Confirm operating voltage, logic level, pinout, memory, USB interface, and maximum GPIO current.
What's this?Image, role, pros, cons, handling & specifications
HX711
A named project component whose exact role is defined by the source circuit and build guide.
What it does hereIt performs a documented electrical, control, interface, or construction function in this project.
Buy / compare this part ↗Advantages
- Selected for this project
- Can be checked independently
- Supports modular troubleshooting
Limitations
- Substitutes may differ
- Generic names can hide variants
- Pinouts and ratings vary
Handling
- Compare the received part with the source
- Keep it labelled
- Do not force connectors or adjusters
Specifications to verify
- Use the exact model, value, package, and rating listed for HX711; similar-looking parts are not always interchangeable.
- Confirm dimensions, ratings, connection method, polarity, and environmental limits.
What's this?Image, role, pros, cons, handling & specifications
PNEUMATIC
A named project component whose exact role is defined by the source circuit and build guide.
What it does hereIt performs a documented electrical, control, interface, or construction function in this project.
Buy / compare this part ↗Advantages
- Selected for this project
- Can be checked independently
- Supports modular troubleshooting
Limitations
- Substitutes may differ
- Generic names can hide variants
- Pinouts and ratings vary
Handling
- Compare the received part with the source
- Keep it labelled
- Do not force connectors or adjusters
Specifications to verify
- Use the exact model, value, package, and rating listed for PNEUMATIC; similar-looking parts are not always interchangeable.
- Confirm dimensions, ratings, connection method, polarity, and environmental limits.
Connect one verified path at a time.
Explore the named components and standardized signal flow, then use Source Check to verify exact physical pins, values, and topology before applying power.
Trace this circuit.
ESP8266 NodeMCU with Load Cell and HX711 Amplifier (Digital Scale): interactive parts, standardized terminals, responsive anchored wires, student explanations, and the original circuit reference in one shared system.
Trace before wiring
Follow power, ground, inputs, processing, and outputs in that order. Never guess a pin from package shape alone.
Connect with power off
Make short, labelled connections and share a common ground only where the schematic requires it.
Inspect every joint
Check continuity, polarity, adjacent shorts, and loose connections before the first power-up.
Open all source diagrams and build views 3 visuals
Confirm the hardware-only control path.
This project does not include firmware in the source. The circuit itself provides the required behaviour.
How to connect
- Match every controller label to the circuit view and source pin map.
- Join grounds before signal wires when separate low-voltage supplies are used.
- Keep motors, relays, pumps, and other loads on a suitable driver and external supply.
Common mistakes
Reversed VCC/GND, board-label versus GPIO-number confusion, missing common ground, and charge-only USB cables.
Troubleshoot
Disconnect loads, continuity-test one path at a time, then test with a current limit.
Software preparation
No IDE, board package, library, or firmware upload is required for this project.
If you add a programmable controller as an extension, document its pin map separately.
How to upload code
The original design is implemented entirely in hardware, so proceed after verifying the circuit and supply.
Assemble, deploy, test, and troubleshoot.
Use the complete source notes in build order, then pass the final checks before calling the project finished.
Build in functional stages
- Power and regulation
- Controller or processing stage
- Inputs and sensors
- Outputs and loads
- Enclosure and strain relief
Power up safely
- Inspect unpowered continuity first
- Apply the lowest safe current limit
- Measure supply rails before signals
- Add one load at a time
- Record expected and actual results
Work from simple to complex
- Confirm power, ground, polarity, and orientation
- Compare each pin with the source
- Test inputs separately from outputs
- Replace only one variable at a time
- Power off before every correction
Follow the documented instructions.
These notes come from this project's source and remain in their original order.
Project overview
Project build noteScale) In this project, you'll learn how to use a load cell and the HX711 amplifier to make a scale with the ESP8266 NodeMCU. First, you'll learn how to connect the scale's load cell, HX711 amplifier, and ESP8266. Then, we'll show you how to set up the scale and give you an easy way to figure out
how much something weighs. Later, we'll also add a screen to show the measurements and a button to "tare" the scale.
Load Cell
Project build noteA load cell turns the force on it into an electrical signal that can be used to measure the force. The electrical signal changes in a way that depends on how much force is used. Load cells come in different kinds, such as strain gauges, pneumatic, and hydraulic. We'll talk about strain gauge load cells in this lesson. Strain gauge load cells have a metal bar with strain gauges attached to it (under the white glue in the picture above). A strain gauge is an electrical sensor that measures how hard something is being pulled or stretched. When an outside force is put on an object, the resistance of the strain gauges changes, which causes the shape of the object to change (in this case, the metal bar). Since the change in resistance is proportional to the load, we can figure out how much something weighs. Most load cells have four strain gauges connected in a Wheatstone bridge (shown below), which lets us measure resistance accurately. To learn more about how strain gauges work, click here.
The wires coming from the load cell usually have the following colours: Red : VCC (E+) Black : GND (E-) White : Output – (A-) Green : Output + (A+)
Applications
Project build noteLoad cells that use strain gauge technology have a wide range of
potential applications. For instance
Project build noteCheck to see if the weight of something changes over time; Find out how much something weighs; Find out if something is there; Estimate a container's liquid level; and etc.
Figure: Circuits Diagram of ESP8266 NodeMCU with Load Cell and HX711 Amplifier (Digital Scale)
Project build noteWe need an amplifier because the changes in strain when we weigh things are so small. Most of the time, a HX711 amplifier is sold with the load cell we use. So, that will be the amp we use. Amplifier HX711 The HX711 amplifier is a breakout board that makes it easy to measure weight with load cells. On one side, you connect the load cell wires, and on the other, you connect the microcontroller. Two-wire interface is how the HX711 talks to the microcontroller (Clock and Data). To connect to the ESP8266, you need to solder header pins to the GND, DT, SCK, and VCC pins. I soldered the wires from the load cell directly to pins E+, E-, A-, and A+. The wires on the load cell were very thin and fragile, so you had to be careful when soldering not to break them. There are several different libraries that can be used with the HX711 amplifier to get measurements from a load cell. We'll use the Bodge HX711 library. It works with the Arduino, the ESP32, and the ESP8266. The two-wire interface is how the HX711 amplifier talks to other devices. You can hook it up to any of the GPIOs on the microcontroller you choose. We are connecting the data pin (DT) to GPIO 12 (D6) and the clock pin
(CLK) to GPIO 13. (D7). You can use any pins that work (check the ESP8266 pinout guide).
You built ESP8266 NodeMCU with Load Cell and HX711 Amplifier (Digital Scale).
You followed the full workflow from understanding the mission to testing the finished project. That is a real engineering achievement - well done.
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