Auto bed leveling with capacitive sensor LJC18A3-B-Z/BX

Hello.. is there somebody, who can help me with capacitive sensor "LJC18A3-B-Z/BX"? It's a NPN NO and I don't know how to connect it to RAMPS 1.4 or how can I test it. I have another sensor (Inductive LJ12A3-4-Z/BY) and when I wire it, it work well.But I'm using glass and I need capacitive.. I wired it as I found here: [www.youtube.com] and here: [www.thingiverse.com]
But unfortunately nothing helps. When I connect it red LED is still shining. When I disconnect ground It still shining (??!) - only +12V and Z-min are connected..
I still have firmware for Z-Probe, I did nothing for this "testing" time.
Thanks and sorry for english..
Tom

These things are a minefield, even when you get it working the performance and repeatability of capacitative sensors is very poor, a few degrees temperature change or a few % of humidity change and they will trigger at different heights, add to that they are usually bulky/heavy, difficult to wire up safely (though not impossible) and offset from the nozzle so you can't probe everywhere, and these are the reasons why I got into the z-probe sensor business, to try to do it much better.

Seriously consider something like DC42 IR sensor, or our Piezo sensor module, you will be very pleased with the results you get compared to these industrial proximity sensors.

If you are going to persist test it on the bench, use a small load on the signal wire to prevent it floating between triggered and open. Work out whether it connects ground or +12v when triggered. Make sure if it supplies 12v on the signal wire you protect your controller by lowering the voltage to 5v (voltage divider/regulator etc...).

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Thanks for reply.. it's bad for me I needed capacitive sensor only because I have glass on MK3 heatbed, so is the better solution to use inductive sensor with larger distance, then standard 4mm? Or use something else then glass, but I don't know what..
Thanks

Have a look at my site in my signature. We use nozzle contact sensors so it doesn't matter what material you print on to. No offsets so your probe offset will be 0,0,-0.1

Accuracy and repeatability that blows a capactative sensor into the weeds.

Edit - depending on how thick the glass is a sheet of aluminium foil under it might mean you can carry on using your inductive sensor, which although not perfect are better than capacitative ones.

Edited 1 time(s). Last edit at 08/24/2017 04:39PM by DjDemonD.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

It looks really good.. Couple of days ago I bought Titan Aero...

(aluminium foil doesn't help, I need sensor with 8mm detection distance I thing. I have 4mm)