Inductive Sensor

Introduction

Inductive sensors are used to sense the Z height on 3D printers. For Marlin with RAMPS - use one that has a 5V output, as opposed to 12V, as RAMPS cannot handle 12V without using additional components.

Part numbers look like LJ18A3-8-Z/BY-5V for the 2018 D3D with LCD screen - where we use the 8 mm distance sensing to facilitate the sensor not hitting the print bed.

• 5V is the critical part - 5V output
• LJ18 - the 18 refers to the diameter of the sensor in mm
• -8- refers to the distance of sensing
• Z/BY refers to normally open vs normally closed

Samples

• From Aliexpress - 3 Wire Polarity: NPN Detection
• Voltage: DC 5V
• Detection Distance: 4mm
• Ouput Status: Normally Open
• Output current: 300mA
• Detection objects: Conductor
• Part number: LJ18A3-8-Z/BX

Notes

• NPN vs PNP - [1]
• See D3D BOM for sourcing.
• See D3D Height Controller for design