Diagram of connection of the capacitive sensor, for the autolevel function, with an optocoupler module.
Sometimes, i was asked for the best auto level system, for a Anet A8, or P3Steel printer. No doubts, for me a capacitive sensor with a optocoupler module.
The LJC18A3-H-Z/BX, capacitive sensor, because, is adjustable from 1 to 10mm, no matter the material to detect. With Aluminium or glass, is good.
The optocoupler module, is easy, i'm not trust with a simple circuit with a diode, or a tension divider, with a couple of resistors.
I need to protect my mainboard, and this way is cheap and easy.
I have, also a design , a little box, to encapsulate the optocoupler module.
Still working in this.
This items, can be found at:
LJC18A3-H-Z/BX 1-10mm Capacitance Proximity Sensor Switch NPN
12V 1 Channel Optocoupler.
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Included electronic scheme of the optocoupler module
Although it was never the purpose of this "thing", attached detailed photos of the circuit for those who want to do it themselves.
UPDATE 05/16/2018: Case for optocoupler module is avalaible:
UPDATE 06/01/2018: Check the pins on your motherboard, it may not correspond to the one shown in the diagram.