ok, sorry for being in a hurry there.
I'm having this digital-clock-circuit that will usally be plugged into the wall, but when I disconnect it from the wall (to move it to a new location or something like that) I want the clock to keep on running (so the time is always ticking, and I don't need to set the time each time I have disconnected it from the wall)
To be able to do this I need some kind of backup power, in this case a 7.2V battery. So what I want to do, is that when the power from the wall is disconnected the battery will kick in. I have tried this with a relay, but the time it takes to switch it from "wall-power" to "battery-power" is much to long, since this is a digital clock the time will be EXACT at all times, and therefore I can't allow it to be a little delay when the clock is disconnected and/or disconnected
So what I simply need is a way to switch between the two power sources, in no time, dependent if power is coming from the wall's 12VDC or not.
The freq. that it will be switching is dependent on how often it will be moved around my house, and I don't think that will be more often than mostly once a week.
Cheers! I Hope I made myself a little more intelligible now :wink: .
Lac