LJ12A3-4-Z/BX NPN Inductive Proximity Sensor 4mm

Product Description

The LJ12A3-4-Z/BX NPN Inductive Proximity Sensor is a non-contact metal detection sensor designed for industrial automation, control systems, and electronic projects. It detects the presence of metallic objects without requiring physical contact, making it useful for position detection, object counting, limit sensing, and machine control applications.

This sensor provides a nominal 4mm sensing distance, allowing it to detect nearby metal targets and generate an electrical switching signal when an object enters its detection range. Its inductive sensing principle makes it suitable for applications where mechanical contact switches may experience wear or where contactless detection is preferred.

The LJ12A3-4-Z/BX operates with a 6–36V DC supply and features an NPN normally open (NO) output. In its normal state, the output is open; when a suitable metal target is detected, the output transistor switches and provides a current-sinking signal. This output configuration is commonly used with PLC inputs, industrial control circuits, and compatible electronic interfaces.

The sensor uses a three-wire connection for straightforward integration into control systems. The typical wire arrangement is brown for positive supply, blue for 0V (GND), and black for the NPN output. A built-in LED indicator provides a visual indication of the sensor's switching state, helping during installation, testing, and troubleshooting.

Its cylindrical M12 threaded metal housing supports convenient installation in brackets, machine frames, and equipment panels. The threaded body also allows the sensing position to be adjusted during installation to achieve the required detection distance.

The LJ12A3-4-Z/BX is suitable for detecting metal components in automated production lines, mechanical assemblies, conveyor systems, and DIY electronics projects. When connecting it to a microcontroller, such as an Arduino or ESP32, the output must be interfaced correctly because the NPN output is not automatically a 5V or 3.3V logic signal. A suitable pull-up or signal-conditioning circuit may be required.

Features

• 4mm nominal sensing distance

• NPN normally open output

• 6–36V DC operating voltage

• Non-contact metal detection

• Three-wire connection

• M12 threaded metal housing

• LED switching indicator

• Suitable for industrial automation

Specifications

Additional electrical ratings, including maximum output current, switching frequency, protection rating, cable length, and operating temperature, may vary between manufacturers and production variants. Confirm these values from the specific supplier datasheet before using them in a final design.

Applications

• Industrial automation systems

• Metal object detection

• Conveyor belt monitoring

• Machine position detection

• Limit and proximity sensing

• Automated counting systems

• PLC input control

• Mechanical equipment monitoring

• Robotics and motion-control projects

• Arduino and microcontroller-based projects with a suitable interface