I am using a potted power supply module that takes 90-305VAC and outputs 12V (at 1.8A). I would really like to be able to run it on 480VAC if necessary. I’m thinking that the right value capacitor in series with the input will drop the voltage from 480V to something more reasonable - let’s say 50%, or 240VAC.
The problem is - the power supply is (literally) a black box. I don’t know what the input circuit looks like, but I don’t think they have any power factor correction, so it’s probably just a full-wave bridge and a capacitor.
I’m looking for suggestions on the best way to make this capacity voltage dropper.