Very interesting.
I suppose there could be a regulator internally. Sure makes things easier. All the cameras I have seen seem to run on either 5v or 12v so I would assume there is a reg inside the camera. I could be wrong, of course!
Nice clean setup you ended up with.
ORIGINAL: Kamikazi
ORIGINAL: Fubar-One
The voltage regulator for the camera, at least in mine, was not in any of the "Y" connections. With mine there was a plastic/rubber "bead" about an inch and a quarter long about midway up the cable between the camera and the RCA connectors. I think all I found in the "Y" was a big blob of solder where all the shielding was soldered together.
Interesting. Mine had no "bead" on the cable. Maybe my camera has an internal regulator, or maybe no regulator at all. It does say DC8V 200mw on the back of the camera. In any case, it seems to work fine on 8 or 9 volts.
Mine looks like this now...