This is my first post here so please have patience with me:
I understand, there are at least two kinds:
a direct contact tester which basically is a neonnlight, and a resistor
a non contact AC meter where a capacitor is involved somehow
I believe in both cases some current, less than a mA has to flow through our body for these to work. I was wondering exactly how much in each case, with an example of a design.
I guess I could buy some for a couple of bucks, and try to figure it out, but I throw the question out here first
EDIT: Progress so far: I/We have found 3 designs so far. I still don’t know how to tell which ones work with magnetic induction and which ones with capacitive coupling. Furthermore, I don’t know where the human body comes into the picture/designs. Here are the designs (from the comments section):
EEVblog #267 (thank you @isdi): https://www.youtube.com/watch?v=AWlRGLxm7nc&app=desktop
Someone here already opened one up: Why are non-contact voltage detectors sensitive to vibration?