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Detect Nearby Objects Without Contact
The Proximity Inductive 4MM Metal Sensor LJ12A3-4-Z/BY is a proximity presence sensor module with digital output designed for obstacle detection, touchless triggers, object counting, and simple automation. It is a practical fit for makers, students, and engineers who want reliable sensor data in embedded builds.
Key details include Working Voltage: DC 6~36V;; the output signal: Low.
Why you’ll love it
- Controller output: Low
- Power range: DC 6~36V;
- Useful spec: NPN 3-wires Normally Open
- Compact size: 2.2 x 6cm
- Maker-friendly build: Easy to use in prototypes, classroom projects, and custom electronics
- Common controller support: Works well with Arduino, ESP32, Raspberry Pi, and similar boards
Compare with similar products
| Product | Sensor style | Standout |
|---|---|---|
| Proximity Inductive 4MM Metal Sensor LJ12A3-4-Z/BY | proximity presence sensor module with digital output | Current item |
| Light Ambient and Proximity Sensor APDS9900 | light sensor with digital output | digital output |
| Capacitive Proximity Sensor LJC18A3-H-Z / BY | proximity presence sensor module with digital output | model LJC18A3-H-Z |
| Infrared Sensor Adjustable E18-D80NK | infrared proximity sensor with digital output | adjustable sensing range, infrared sensing |
What you can build
This sensor is a good fit for robot obstacle avoidance, touchless dispensers, automatic doors, object counters, parking aids, and level alarms.
Starter bundles
Pair it with an Arduino-compatible board, ESP32, or Raspberry Pi, plus a breadboard and jumper wires for quick setup and testing.
Recommended add-ons
Useful add-ons include a microcontroller board, jumper wires, and pull-up or pull-down support when needed, depending on how you plan to power, mount, and log the sensor.
Technical specifications
| Product | Proximity Inductive 4MM Metal Sensor LJ12A3-4-Z/BY |
|---|---|
| the output signal | Low |
| Working Voltage | DC 6~36V; |
| Type | NPN 3-wires Normally Open |
| Blue | GND |
| Brown | VCC |
| Black | Output |
| Dimension | 2.2 x 6cm |
| Detecting Distance | 0~4mm |
Wiring & usage notes
Connect power and ground, then wire the output pin to a digital GPIO input. Check whether the module uses active-high or active-low logic in your code.
What’s in the box
1 × Proximity Inductive 4MM Metal Sensor LJ12A3-4-Z/BY
Frequently Asked Questions
What does the Proximity Inductive 4MM Metal Sensor LJ12A3-4-Z/BY measure?
It is designed to measure nearby objects, remote IR signals, or motion.
Can I use it with Arduino, ESP32, or Raspberry Pi?
Yes. It is well suited for common maker and embedded platforms, as long as you power it at the correct voltage and match the signal level to your controller.
How do I connect this Digital GPIO sensor?
This sensor provides a digital switching-style signal that is easy to read from a GPIO pin.
What affects accuracy?
Power quality, wiring, mounting, target material, and the real environment can all affect the reading. It is best to test and calibrate in the final setup.
Is it good for prototyping?
Yes. It is a practical choice for learning, proof-of-concept builds, and small automation projects.
Manila stock. Order before 16:00 PHT, ships today via J&T or LBC. Provincial: 1–3 working days.
Schools / class POs: we accept Purchase Orders for accredited schools and universities. contact us with your PO details.
Returns: 7-day inspection window for DOA units. Email proof of issue and we ship a replacement.
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