Before I implement some DIY sensor reversing circuit on my 3d printer I thought I should talk about it here just to be safe. I'd hate to break something on it.
So, I am trying to use the auto bed leveling of my delta printer to cut my own PCBs. The way this works is you auto bed level and use alligator clips as sensor - sensing continuity when the bit touches the copper board to be milled.
Unfortunately, I found out that the polarity of that sensor on my printer is reversed - the sensor thinks it is triggered when there IS continuity. There is no easy way to reverse the polarity through software on my printer so I though I should make a hardware that reverses it
After some thought I came up with the next schematic. I am no expert though - that is why I am posting before I do something irreversible to my printer.
Am I doing something wrong that I am unaware of?
EDIT1: The 5V on the sensing side is probably a pulled-up input
EDIT2: I am afraid that current could flow through the milling side and through that resistor to ground thus keeping the sensor "open". Should I be using an opto-coupler? I couldn't measure the pull up resistor value