Hi. I have a charger for 18v Dewalt Li-Ion (dc9130 120v 60hz) and I'd like to find a circuit diagram so I might be able to convert it to use with 240v 50hz. So I probably need the diagram for the 240v one as well to replace whatever needs it? I'm experienced in such shenanigans! Thanks.

Most chargers will fuction on 240/50 hz, look closely at the writing on the charger, it may say. I have laptop chargers and have used the overseas with no problem, that being said, you might try contacting dewalt and asking them if you can do it. Like I said, it probably already will work without doing anything. i have seen some devices (amplifiers mostly) that have a switch on the bakc to switch voltage, ( I don't recall ever seeing a switch to change line frequecny though), hope this helps a bit