12mm cylindrical inductive proximity sensor with NPN normally-open output and IP65 weather resistance. Detects ferrous and non-ferrous metals within 2mm without physical contact. 6–36V DC, 500Hz switching frequency. Standard for CNC homing, 3D printer bed levelling, conveyor systems, and robotics. Includes clamp nuts and washers.
Specifications
| Model | LJ12A3-2-Z/BX |
| Body Diameter | M12 (12mm) |
| Body Length | ~64mm |
| Sensing Distance | 2mm (±10%) |
| Output Type | NPN, Normally Open (NO) |
| Supply Voltage | 6–36V DC |
| Output Current | ≤300mA (sink) |
| Switching Frequency | 500Hz |
| Cable Length | ~100cm |
| IP Rating | IP65 |
| Housing Material | Nickel-plated brass |
| Target Material | Ferrous & non-ferrous metals |
Wiring — 3-Wire NPN
| Brown wire | VCC — connect to positive supply (6–36V DC) |
| Blue wire | GND — connect to negative / ground of supply |
| Black wire | Signal output — pulls LOW when metal detected (NPN open collector). Connect to your input pin with a 10kΩ pull-up to VCC. |
Using with Arduino (5V): Power the sensor from the Arduino 5V pin (minimum operating voltage). Connect Brown → 5V, Blue → GND, Black → digital input pin. Add a 10kΩ resistor from the input pin to 5V as a pull-up. The pin reads HIGH when no metal, LOW when metal is detected.
Using with 12V/24V PLC or system: Power from your 12V/24V supply. Use a voltage divider or logic level converter on the black signal wire before connecting to a 5V or 3.3V microcontroller input.
Using with 12V/24V PLC or system: Power from your 12V/24V supply. Use a voltage divider or logic level converter on the black signal wire before connecting to a 5V or 3.3V microcontroller input.
What's Included
| 1 × | LJ12A3-2-Z/BX inductive proximity sensor with ~100cm cable |
| 2 × | Clamp nuts |
| 2 × | Lock washers |
Common Uses
CNC machine homing, end-stops & limit switch replacement
3D printer bed levelling & axis limit detection
Conveyor belt object counting & position sensing
Robotic arm & actuator position feedback
Industrial metal part presence/absence detection
DIY automation & maker projects
Common Questions
Will this detect aluminium or copper?
Yes, but at a reduced sensing distance — typically 40–50% of the rated 2mm. So expect reliable detection at ~1mm for non-ferrous metals. For iron/steel, the full 2mm range applies.
Can I use this as a filament runout sensor on my 3D printer?
Not directly — it detects metals only, not plastic filament. It's ideal for axis limit switches and bed levelling probes on metal print beds, but not for filament runout detection.
Please note: Detects metal only. Non-ferrous metals have ~40–50% reduced effective sensing range. Do not exceed 36V supply voltage. Includes 2 clamp nuts and 2 lock washers.