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I have one of these inductive sensors marked as PL-08N which should work within a 4-30 VDC range and trigger at 8 mm or less. It's clearly a knockoff, meaning it has no manufacturer marking and all info is printed on a sticker.

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I'm testing it's functionality so I tried to wire 12 V to brown, GND to blue and I'm probing the black wire, but I'm experiencing a weird behaviour: the sensor properly triggers, but it doesn't recover, meaning the LED won't turn off moving the sensor away from the plate and the black wire doesn't go back to 0 V.

What am I missing?

UPDATE

Looking for solutions I tried to run the device at 5 V (still within the declared range) expecting to have a very low sensitivity, just to discover:

  1. it activates at about 8 mm from the print bed (4 mm from my borosilicate glass)
  2. it properly recovers immediately after I move it away

I thought those devices had increased sensitivity with greater voltages...

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  • $\begingroup$ You seem to have connected it correctly, indeed strange behavior. Once you remove a metal object the sensor should react on the change immediately. Could be a defective sensor. $\endgroup$ – 0scar Feb 27 '19 at 14:54
  • $\begingroup$ your later observation is interesting, but it might be how the device itself is set up: some devices are rated for a range and internally have some sort of regulator that results in actually just using a certain voltage, making them useable in a wider variety of systems. $\endgroup$ – Trish Feb 27 '19 at 16:33
  • $\begingroup$ @Trish I fail to get how an internal regulator would cause the output to latch on activation when the supply gets higher well within the declared range... I mean, I'm not even getting close to the maximum allowed 30 V $\endgroup$ – Roberto Lo Giacco Feb 27 '19 at 23:05

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