The TV in our TT came with a brick power supply and barrel connector. The power supply was rated for 12V, so I bought another barrel connector at Radio Shack along with a cigarette lighter power cord. After verifying the polarity 3 times I plugged it into the 12V outlet and turned it on. Voila! - TV on 12V!
And to boot the Jensen radio / DVD player is also 12V. So our granddaughter got to watch a few DVD's while we dry camped.