LJ12A3-4-Z/BY PNP NPN Inductive Proximity Switch 4mm Sensing
LJ12A3-4-Z/BY PNP NPN Inductive Proximity Switch 4mm Sensing
LJ12A3-4-Z/BY Metal Inductive Proximity Switch — PNP & NPN, 4mm Sensing Range
Upgrade your automation setup with the LJ12A3-4-Z/BY Inductive Proximity Switch. This compact, cylindrical metal sensor delivers reliable, contactless detection of metallic objects with a precise 4mm sensing distance. Available in both NPN (LJ12A3-4-Z/BX) and PNP (LJ12A3-4-Z/BY) output configurations, it integrates seamlessly into CNC machines, robotic arms, conveyor systems, 3D printers, and other industrial or DIY automation projects.
Made in Mainland China.
Key Features
- 4mm Sensing Range: Accurate, consistent detection of metallic targets without physical contact.
- Dual Output Options: NPN (sinking) and PNP (sourcing) variants to match your controller's input requirements.
- Metal Housing: Durable construction designed to withstand industrial environments, vibration, and daily wear.
- Low Voltage Compatible: Operates safely below 50V AC or 75V DC (EU LVD compliant).
- Easy Installation: Standard M12 cylindrical body with threaded barrel fits most standard mounting brackets.
- Wide Application: Ideal for robotic arms, CNC homing/limit sensing, 3D printer endstops, conveyor lines, and position detection.
- No High-Concern Chemicals: Clean and safe material composition.
Specifications
| Model | LJ12A3-4-Z/BX (NPN) / LJ12A3-4-Z/BY (PNP) |
| Sensing Distance | 4mm |
| Housing Material | Metal (M12 Cylindrical) |
| Output Type | NPN / PNP |
| Operating Voltage | Below 50V AC or 75V DC |
| Package | 1 x Inductive Proximity Switch |
| Country of Origin | Mainland China |
What's in the Box?
- 1 × LJ12A3-4-Z/BY PNP or NPN Metal Inductive Proximity Switch
Note: Color may vary slightly due to monitor display differences. Manual measurement tolerances are normal and expected.
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Frequently Asked Questions
Q: What is the difference between the NPN and PNP versions of the LJ12A3-4-Z proximity switch?
A: The NPN version (LJ12A3-4-Z/BX) outputs a sinking signal — the output wire pulls LOW (to ground) when an object is detected, commonly used with PLCs and microcontrollers that accept NPN inputs. The PNP version (LJ12A3-4-Z/BY) outputs a sourcing signal — the output wire pulls HIGH (to supply voltage) when activated, suited for systems expecting PNP inputs. Choose based on your controller's input type.
Q: What materials can the LJ12A3-4-Z/BY inductive proximity switch detect?
A: As an inductive proximity sensor, this switch detects metallic objects only — including steel, iron, aluminum, copper, and other conductive metals. It does not detect plastic, wood, glass, or other non-metallic materials. The maximum sensing distance for ferrous metals is 4mm.
Q: Is this proximity switch compatible with 3D printers and CNC machines?
A: Yes! The LJ12A3-4-Z/BY is a popular choice for 3D printer bed leveling endstops and CNC machine homing/limit sensing. Its standard M12 threaded cylindrical body fits most commonly available mounting brackets, and both NPN and PNP variants are widely supported by popular control boards.
Production & Packaging Notice
To maintain high stock availability and fast shipping times, our items are sourced from multiple verified manufacturing facilities. While the core quality, materials, and product specifications remain identical, you may notice slight variations in the packaging design, manufacturing origin, or the wording of the printed instructions.