Quote Originally Posted by nova_robotics View Post
Good stuff. Have you given any thoughts of powering it with a little isolated power supply and using an optoisolated output?

I was going to make a touch sensor circuit for my mill, but it's very dry in my shop and I get static shocks off of everything. I have to ground myself on metal surface probably every 15 seconds or so. It's just second nature to brush my hand against every metal tool as I'm walking around. I'm worried about zapping the GPIO pin on my DRO. So... I figured completely electrically isolating the input and output side of the touch circuit might be a good thing. You probably wouldn't even have to modify your circuit.
You are right on both counts. Isolated power is necessary because we do not want any stray current entering the EEF. If connecting to a separate circuit, an opto is the way to go. You can see the isolated power supply on page 10 and mention of the opto on page 9.

I live in the Sonoran Desert so am no stranger to dry conditions. When I first moved here and set up my DRO, I blew it up with the first static discharge.

Rick