Inductive Limit Switch problem

[Kitwn]

If it were me I'd be doing the following:

1) Add a decently low (<= 2K2) pullup on the output of the switch to 24V
2) remove the diode
3) Increase R2 to 10K
4) add a 2K7 resistor across the PCB header pins
5) up C1 to at least 10nF
6) remove R3

This should give a decent voltage swing on the switch output and a 0.1....+4.5v ish swing on the input to the 'HC14 with a bit of filtering and a 12dB attenuation of noise on the switch output to boot.

After I put up the last post I thought for a while and realised that using a diode was the wrong way to do this and that a simple potential divider with the BOB input seeing the open collector of the sensor directly was a far better idea as you suggest. I have a spare sensor and a spare BOB (that's one of the advantages of using a cheapo board instead of a $900 one) so I'll try those component values and check the volts. Thanks for working out the values.

It's tempting to try replacing the surface mount components on the BOB but I think an external bit of Veroboard with all the new bits soldered on will be the best option.

Doddy,
Come to think of it, I've probably got a quad opto-coupler or two in stock though I'll need to print up a surface mount PCB to use one of those. I feel a rummage through my drawers coming on!