Hi all, I'm working on a adjustable 0-2kV power supply. I'm interested in taking a high side current measurement to monitor for excessive current draw from a PhotoMultiplier Tube. The typical current draw should be between 0.5mA to 2mA. However, from my understanding as the tubes start to go bad they begin drawing more current, up to 20mA. I will be reading the current through an analog input on the Arduino and displaying it to an LCD. The PMT is ~5Mohm IIRC.
My first thought is to make a current divider circuit but I'm somewhat hesitant to have so much potential so near the Arduino. Is this okay as long as I'm biased to ground?
If not, what is the best way to go about safely taking these measurements on the Arduino?
I've read a little bit about isolation amplifiers, and they seem like it might be the right approach but I don't fully understand how to go about implementing one. Any thoughts?