Would 12V input to the 7805 damage the regulator/system?

[Biased]

The reason I'm asking is so I can play SNES on the DVD system in my brother's car. I'm planning to rewire a cigarette lighter adapter to the power connector of the SNES and I want to know if I need to do any modifications to the plug before I hook my SNES up to it.

[Life of Brian]

Not if you're using the original 7805 with heatsink that the system came with. I believe a 7805 regulator can take up to 30-ish volts without a problem. The higher voltage you put in = more heat, so make sure you have that heatsink still.

[Triton]

minimum input voltage on a 7805 to get 5v out is around 7-7.5 iirc. the higher the voltage the hotter it gets. anything over 10-12v i'd heatsink or it might burn itsself up lol

[themadhacker]

i got a nasty burn once from an unheatsinked 7805 with 12 volts going through it. make sure there is a heatsink on it. and if it's in a small area, i'd put a fan on it too.

[nevermind1534]

Most of the cheap "replacement" NES power cords on ebay will actually output 12V, rather than the 9V that they say they do. If you can give it less, it definitely wouldn't hurt, but 12V won't kill it if it's adequately cooled. The heatsink that the NES has on the 7805 does get very hot from 12V, though, because I'm pretty sure that they only designed it for 9V. If you use a nice heatsink, I can't see why it wouldn't work.