LJ12A3-4-Z/BX M12 Inductive Proximity Metal Sensor (NPN NO DC6-36V) | Pro Tronix

Product Description

The LJ12A3-4-Z/BX is the industry-standard choice for rugged, non-contact metal detection in automation, CNC systems, and 3D printers. Housed in a durable, threaded M12 nickel-plated brass body, this inductive sensor detects any metallic target up to $4\text{mm}$ away without physical contact, eliminating mechanical wear and tear.

Operating over a wide input voltage range of DC $6\text{V}$ to $36\text{V}$, this sensor features an NPN Normally Open (NO) output. In its idle state, the output line is open (floating). When a metallic object enters the detection field, the internal NPN transistor activates, pulling the output line directly to Ground ($0\text{V}$). This active-low logic makes it highly reliable for high-speed counting, limit switching, and automated positioning tasks.

Pinout / Layout Connections

The sensor comes with a high-durability, flexible 3-conductor cable utilizing standard industrial color codes:

• • Brown Wire (VCC): Connect to the positive power supply ($+6\text{V}$ to $+36\text{V}$ DC).

  • Blue Wire (GND): Connect to the common system ground ($0\text{V}$).

  • Black Wire (OUT): NPN Normally Open (NO) active-low signal line.

    • No Metal Detected (Idle): The output floats open.

    • Metal Detected (Active): The output is pulled to Ground ($0\text{V}$).

    • Important Microcontroller Connection Note: Since the sensor operates on $6\text{V}$–$36\text{V}$ but most development boards (like Arduino or ESP32) run on $5\text{V}$ or $3.3\text{V}$, you should not connect the black signal wire directly to your board. Instead, use an optocoupler, a simple voltage divider, or a logic level converter to step down the signal safely. Alternatively, take advantage of the NPN open-collector design by connecting the black wire to your microcontroller input with its internal pull-up resistor enabled, ensuring the sensor’s operating voltage stays separated from the data line.

Available now from Pro Tronix with guaranteed quality and fast delivery nationwide.