I am using an old Eclipse HU and Alpine amp in my shop powered by a 25 amp 12v power supply. All is well except that I lose my settings every time I turn it off. Is there a way to connect the constant so I don't lose my settings?
You would either need to leave your power supply on 24/7, which I don't recommend, or connect a battery to your constant +12v lead. I considered using a backup battery from an alarm project that I scrapped, but I don't know how long it will allow the HU to retain memory before discharging.
Then again, therein lies another problem, will your power supply allow you to charge a battery? I know mine will, but I am not sure of others.
I may have answered my own question. While looking through my electronics junk drawer trying to find an alligator clip to try to connect a rechargeable battery to my power supply, I found a .5 amp 12v wall plug with cigarette lighter adapter. Voila! Uses less electricity than a home receiver powered off and keeps my settings.