LJ12A3-4-Z/BY PNP DC 6-36V 4mm Tube Type Inductive Proximity Sensor Switch
⚙️ Inductive Proximity Sensor (LJ12A3-4-Z/BY)
🧩 Overview
Industrial non-contact metal detection sensor
Type: Inductive Proximity Sensor (PNP, Normally Open)
Detects metal objects only
Cylindrical M12 tube-type design
Used in automation, CNC, robotics, 3D printers
⚙️ Working Principle
Sensor generates an electromagnetic field
When metal comes near → eddy currents are induced
This disturbs the magnetic field
Sensor detects change → switches output ON/OFF
👉 Works without physical contact (no wear & tear)
📊 Key Specifications
🔹 Operating Voltage: 6V – 36V DC
🔹 Output Type: PNP, Normally Open (NO)
🔹 Detection Distance: 4 mm
🔹 Output Current: Up to 300 mA
🔹 Sensor Diameter: 12 mm (M12 thread)
🔹 Response Frequency: ~0.5 kHz
🔹 Operating Temperature: -25°C to +70°C
🔹 Cable Length: ~1–1.2 m
🔹 Protection: Reverse polarity & short-circuit protection
🔌 Wire Configuration (3-Wire PNP)
🟤 Brown → VCC (+6–36V)
🔵 Blue → GND
⚫ Black → Output (signal)
👉 Output becomes HIGH when metal is detected
🔄 Features
Non-contact detection (no mechanical wear)
High repeatability & accuracy
Fast switching response
Resistant to dust, oil, vibration
Built-in LED indicator
Suitable for harsh industrial environments
🛠️ Applications
CNC machines & automation 🏭
3D printer auto bed leveling
Conveyor belt object detection
Position sensing in robotics 🤖
Limit switch replacement
Metal detection systems
⚠️ Usage Tips
Detects only metal (not plastic/wood)
Maintain distance ≤ 4mm for detection
Use proper voltage (≥6V required)
For microcontrollers → use voltage divider or relay
Ensure correct PNP/NPN selection before wiring
✅ Advantages
No physical contact → long lifespan
High durability in industrial use
Fast and reliable switching
Easy installation (threaded mount)
⚠️ Limitations
Cannot detect non-metal objects
Fixed detection distance (not adjustable)
Requires higher voltage than Arduino (needs interface circuit)
🔍 Summary
Inductive proximity sensor (PNP NO)
Detects metal objects within 4mm range
Operates on 6–36V DC
Ideal for industrial automation & robotics
