Thread: Regulated/ unregulated relay switch?

Could somebody give me a sanity check on this please? I'm trying to get a tank circuit working in my system that a tech-savvy friend of mine designed (he's on holiday dammit!) and it just occurred to me that there may be an easier way to do this..

I have seperated my motherboard and 3.5" HDD from the rest of my 12v devices (fans and lights) which are run direct from cars 12v supply, with my epia 900 I have measured a maximum current drain of 5A from my variable PSU on the bench (er dining room table).

My question is, I have a couple of high power regulators lying around which can supply 12v at 5A, could I use these to power my inverter when the engine is running and use a relay to switch to the unregulated 12v input from the car battery when the engine is off. This should get past the voltage drop through the regulator shutting off the inverter, and I was thinking of using a 1F capacitor after the relay and before the inverter to 'fill in' during the relay switching and to survive crank.

Any comments?