load cell ( 3 KG )
🧠 What is it?
A 3KG Load Cell is a sensor used to measure weight or force up to 3 kilograms.
It works by converting mechanical force into an electrical signal using strain gauges.👉 Commonly used in digital weighing scales and DIY electronics projects.
⚙️ How It Works
The load cell is based on the strain gauge principle:
When weight is applied → the metal beam slightly deforms
Strain gauges attached to the beam change resistance
This change produces a very small voltage (millivolts)
The signal is read using an amplifier like HX711 Load Cell Amplifier
🔌 Wiring (Typical 4-Wire Load Cell)
| Wire Color | Function |
|---|---|
| Red | Excitation + (E+) |
| Black | Excitation − (E−) |
| Green | Signal + (S+) |
| White | Signal − (S−) |
👉 These connect directly to the HX711 module
🔄 Working Flow
Weight Applied
↓
Metal Beam Deforms
↓
Strain Gauge Resistance Changes
↓
Small Voltage Generated (mV)
↓
HX711 Amplifies Signal
↓
Microcontroller Reads Weight
📊 Key Specifications
Capacity: 3 kg max
Output: mV/V (millivolt per volt)
Accuracy: depends on calibration
Type: Usually single-point load cell
Material: Aluminum alloy
🧠 Important Characteristics
1. Very Small Output Signal
Output is in millivolts
Cannot be read directly by Arduino
👉 Requires HX711 module
2. Requires Calibration
Raw values ≠ weight
Must calculate calibration factor
3. Sensitive Placement
Must be mounted properly for accurate results
🚀 Applications
⚖️ Digital weighing machines
🛒 Smart carts
🤖 Robotics force sensing
🧪 Lab measurements
🏠 IoT weight monitoring systems
✅ Advantages
High accuracy
Good repeatability
Compact size
Low cost
⚠️ Limitations
Requires amplifier (HX711)
Sensitive to vibration
Needs proper mounting
Overloading can damage it
🔧 Mounting (Very Important)
Typical setup:
One side fixed (bolted)
Other side free to bend
👉 Wrong mounting = incorrect readings
💡 Example Use
Digital weighing scale:
Place object → load cell bends
Signal changes
HX711 reads data
Arduino displays weight
🔍 Practical Tips
Do not exceed 3KG limit
Use a stable base
Calibrate with known weights
Avoid sudden shocks
🔁 Load Cell + HX711 Combo
| Component | Role |
|---|---|
| Load Cell | Senses weight |
| HX711 | Amplifies & converts signal |
| Arduino | Processes & displays |
🧪 Real-Life Example
In a kitchen scale:
Load cell detects weight of food
HX711 processes signal
Microcontroller shows weight on display
){kind=link}