we have a car radio in our caravan, its currently in storage and i can rember if that loses the settings every time we turn of the power. But i am not to botherd if i lose the radio settings everytime, or though it would be a nice touch. is there not anyway of hooking up a standard 1.5v battery to keep the settings?
Just leave the power supply turned on but turn off the radio manually. Wire the 12 volt line to both the switched and unswitched power line on the radio.
Alternatively, you can use a sealed lead acid battery as a backup although you'll need to put a charger on it.
Old car battery and a charger plugged into the wall will also work as long as the charge r can supply the battery. However, by that time you are already up into the cost of an AC-DC power supply so you might as well go with that.