Circuit for New Radio
 

So, I broke down and bought a Retro sound radio that looks vintage but has all the modern items in a radio. Radio sounds great but I only had a "hot wire" connected to the old Blaubunkt radio which works for this new one but when the ignition is off, none of the settings are saved.

My question is, what is the best circuit to run a wire to so that the radio is connected to the battery and will save the radio settings amongst other settings. Specifically what wire color should I be looking for under the dash? The hazard circuit? Others?

I have installed and changed so many stereos that I can't remember,but what I do remember is the poor way's I have seen so many installs,I like to power off the fuseboard as the maker intended,or even better is to feed your power straight from the battery but in the case of the 914 this is a more of a hassle but using the right gauge wire will get you there,if you choose this route you know you are getting full voltage to the unit.
Your earth for your headunit is really important it needs to be taken from a known correct point,best is where the factory have them,or drill and mount one for yourself to a bracket or similar,remember to scrape the paint back for a better contact.
Your constant power supply (usually yellow wire) for your head unit memory is taken off fuseboard or again the battery but needs to be fused if you go to the battery.
I like the Retro-sound units they seem to have a strong following amongst classic car guys and are a nice addition ,good luck setting up and remember a probe tester and multimeter in your tool kit ;).

Thanks for this information. The car had an AM radio that has a red wire with fuse running from the fuse board. There is also a ground wire pinned to a bolt that's attached to the frame of the car.

I do have the yellow wire and that's the one I want to connect to the fuse board. Is the emergency flasher circuit the best one to use for a constant power supply? What gauge of wire do you recommend?

The Yellow from the new radio is the memory circuit and does not draw very much power. Use the same size wire as the radio as a minimum size. an 18 or 16 gauge wire would be fine. Connect it to any fuse that has power with the key off.

Pablo - Mike absolutely knows what he is talking about.

Cool. Thanks all!

So you have your main power supply connected ,you should also have a switched (by ignition) wire also ,this will be a smaller gauge wire than the main power wire.
This wire powers the unit to turn it on @ first click of the key and is wired to the ''acc'' contact on the back of the switch.