PNP Inductive Proximity Sensor – LJ12A3-4-Z/BY 4mm Detection

Description

The LJ12A3-4-Z/BY Inductive Proximity Sensor – PNP NO, 4mm Detection is a non-contact, cylindrical inductive sensor designed for detecting metal objects in industrial and DIY applications. Operating on a 6–36V DC supply (300mA max output), it features a PNP normally open (NO) output, sourcing voltage to the load (e.g., a microcontroller or PLC) when a metal object (iron/steel preferred, non-magnetic metals reduce range) is detected within 4mm (±10% accuracy). The sensor uses inductance principles, emitting an electromagnetic field and detecting changes when metal enters its 12mm-diameter sensing area, with a response frequency of 0.5kHz for reliable switching. Its M12 threaded metal shell (12mm diameter, 62mm length) and 1.1–1.2m three-wire cable (brown: +V, blue: GND, black: signal) ensure durability and easy installation, with an IP65 rating for dust and splash resistance. The sensor includes a red LED indicator that lights when metal is detected, aiding setup. With a working temperature range of -30°C to +60°C (non-freezing), it’s suitable for harsh environments like machine tools, CNC systems, and 3D printer bed leveling (e.g., detecting aluminum print beds). The LJ12A3-4-Z/BY offers short-circuit and reverse polarity protection, enhancing reliability. For Arduino projects, connect the black wire to a digital input with a 10kΩ pull-down resistor to ground, and power via 12–24V (not directly from Arduino’s 5V due to voltage mismatch). Compatible with platforms like Arduino, Raspberry Pi (via level shifters), and PLCs, it’s ideal for automation, conveyor systems, and robotics. This RoHS-compliant sensor (45g, 20mm washer included) outperforms mechanical limit switches in longevity and precision. Note: Detection range may vary with supply voltage (4mm at 24V, ~2mm reported in some cases) and object size/material; test with a caliper for accuracy.