Baomain Capacitive Proximity Sensor Switch LJC12A3-5-Z/BY PNP NO DC 10-30V 200mA 1-5mm Blue

I bought 4 of these Baomain Capacitive Proximity Sensor Switch. There are no instructions with the sensor. Initially, two of the sensors would not function properly. After doing some research I discovered that there is a tiny adjustment screw on the back end of the sensor to adjust the sensitivity. They now function properly. There is a tiny schematic on the label that shows how to connect the wires. Turns out the colours on these PNP sensors is not 'traditional', Black, brown and blue, signal, load and negative (or ground).

Excellent

Received as advertised. The adjustment for distance is a little sensitive but it works just fine.

Good

Since I upgraded my Printrbot simple metal to a heated bed with glass build surface, I was getting poor performance out of the inductive sensor that came with it, for obvious reasons. I figured a capacitive sensor was the best upgrade path, and all the numbers for this listing fit my needs. (PNP/NO, same size, works with 12v, etc.)It DID work, though I had some difficulty.First, when the sensor is "off" that is, untriggered, voltage leaks through enough to trigger the endstop. The fix for this was to tie the sense wire down to ground weakly using a 10k Ohm resistor, to bleed off the leakage current. That worked for a while, months and dozens of prints in fact. . . until suddenly it didn't.Just today, (~6 months later) after three successful prints back to back, I went to start a fourth one when the printer suddenly wouldn't home the Z axis anymore!? Running a M119 showed that the z-min end-stop was permanently triggered, in spite the sensors light being off.While poking around trying to figure out why it had suddenly started acting up, I began to notice a little puff of smoke billowing out of the bottom of my printer!!! Naturally, I pulled the power plug as quick as I could. Then I went fast to work dissecting the printer to try and figure out what had just happened.According to the RepRap wiki, there is a buffering MOSFET on the Z-endstop input/signal (Q4 on the schematic) which allows the Z-endstop to be triggered from either 5V or 12V. APPARENTLY this sensor put that transistor into a bad operating area, causing it to smoke.I am extremely fortunate that the main AT90USB microcontroller didn't get cooked at the same time this transistor did, since that transistor is attached directly to pin 18. Since it ISN'T broken, luckily, I can just bridge the pads and install an intercepting circuit that will condition the sensor input, whatever that may be now.Bottom line, this sensor is supposed to be a digital thing, off or on. It is certainly NOT supposed to put out signals somewhere in the middle, which is most likely what fried my poor MOSFET.Edit: After thorough testing, the sensor proves to be dead.LED blinked, but signal wire did nothing. Avoid.